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DIY Stompboxes => Building your own stompbox => Topic started by: Jaicen_solo on October 26, 2005, 02:19:59 PM

Title: New Looper Design
Post by: Jaicen_solo on October 26, 2005, 02:19:59 PM
Having recently acquired some new enthusiasm for this project, I've started work on a rough layout for a new looper based on the ISD2560 chip. This has 60s of record time, and a frequency response of up to 8k, with a 3db low pass at 3kHz.

Layout is HERE:
http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUOANAC5Ox-TYgamnnHrOv188MZlwEzapoF0LvNxgK5E6M6S62D8P6ro5RJb8yUMmRTQmYkDDp7_aK-Jgv3y-tfGg3QfkI9kBgpUHF9gm25Tg

I've been working from the data sheets here:
 http://www.winbond-usa.com/products/isd_products/chipcorder/applicationinfo/apin12.pdf
 http://www.winbond-usa.com/products/isd_products/chipcorder/datasheets/2560/ISD2560.pdf

Which is where the schematics can be found. So far, i've only laid out the ISD portion of the circuit, no external mixers etc.
At the minute, the layout is very rough and far too spacious but that can all be refined later. I Just wanted to see if anybody was interested in this new design, and could perhaps cooperate to check for errors.
Let me know what you think, all comments welcome.
*bob
Title: Re: New Looper Design
Post by: nelson on October 26, 2005, 05:29:12 PM
If I can get hold of the chip I will be glad to help you "refine" the PCB. After you have the full version schem drawn up.

It is about time we had a looper pedal that didnt rely on a NOS chip that is too expensive.


Count me in!

hempathyathempathydotorgdotuk
Title: Re: New Looper Design
Post by: The Tone God on October 26, 2005, 07:16:11 PM
I had a looper design awhile back that used the 25xx ICs as I thought the old design was silly to use an out of date IC. Maybe I'll look into porting my mods to this design. We'll see.

Andrew
Title: Re: New Looper Design
Post by: Jaicen_solo on October 27, 2005, 06:21:54 AM
Sounds like a plan. I intend to just make it a straight looper for now, no FX loop etc.. Say a looper Lite edition.
Once it's finished maybe you can help us refine a more complicated luxury edition?  ::)
I figure this way, those less confident will be able to build a simple looper with easy to get parts, while the adventurous can work on something a little more challenging. I chose the 2560 because it was for me the easiest to get hold of, both maplin and RS stock it in the uk.

Title: Preliminary Layout Posted
Post by: Jaicen_solo on October 27, 2005, 09:26:11 AM
Ok guys, thought I'd share this morning's work with you all.

I've laid out a rough looper using just 3 transistors, a 2560 and a TL074. So far, the mixer design only includes Input gain and blend controls, but that can probably be improved upon with FX loops and tone controls for example.
I think we can probably make this layout fit into a Hammond BB box with a little refinement, but at the minute I'm shooting for a B size box (still not done the power supply).
I'm going to draw up a schem for the mixer etc in a minute. Basically, the first input stage (IC1D) is a gain stage using the 500K pot. This feeds straight into IC1B which buffers the signal and passes it into both the input of the 2560 chip (IC2) and the DRY/WET blend control.
IC1C just buffers the output of the 2560 (because it was spare basically) and passes the output to the other side of the 100K blend pot.
The middle lug of the blend pot is attached to IC1A which buffers the blended output and outputs via a 10uF cap and 1M to ground to the output jack.
All of this has been done off the top of my head, so if anybody spots any corrections let me know. I'd also be interested in eliminating a few components, I went with the kitchen sink approach, so any thoughts??
Another thing to note, the layout is done as if the IC's Are surface mount. It'll need to be mirrored to use as an actual PCB. I just couldn't get my head around all those IC2 pins backwards!  :icon_eek:
Anyway, the artwork is shown below.
NOTE: I've tried to keep the Digital and Analogue grounds seperate. If anybody spots any errors there let me know. (I spotted the Pin28 error, that's now connected to +6v)

Layout Here: http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXwtE4rB8zfeRk_zT0RvDPKu0Zb4dgabxeUNwuXQ0XxxBOgaWxdLWUmPfYoJ2yjKa2OApZ9cSP4_hb0KyhV35Tfct0kTN_STt02FTSvSh_0Jw

PCB Traces Here: http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXQMi7CfRrdvucCAHca-j1m8ZqTQShNwMIy34iL7eTYObFtkNvJ4KThdF4vBF90sdoPHa1G4mAD1DCFNIkz20tfnU0HNNxUt3yIYtcpfmiOkA
Title: Re: New Looper Design
Post by: Gladmarr on October 27, 2005, 10:23:57 AM
can the Winbond chips be made to play forward/backward?  Variable speed?  Overdub?  These are features I would be requiring in a looper if I were to make one.  It seems there's something to be desired in their sampling frequency rates as well.
Title: Re: New Looper Design
Post by: Peter Snowberg on October 27, 2005, 10:33:19 AM
I think it was Z.Vex who posted about modulating the speed of these chips by modulating supply voltage.

Sorry, they cannot play backwards or overdub.
Title: Re: New Looper Design
Post by: Jaicen_solo on October 27, 2005, 10:35:37 AM
Ermm, no, no and.. No. Sorry!

These chips just aren't designed for something like that. The record and playback functions are mutually exclusive, unless you get into daisy chaining multiple devices. That's not really what this project is all about.
The sample rates are not too bad really, once you start putting a little crunch on the amp it's going to sound pretty much ok. The only thing that really suffers is the high frequency response or lack of. That said, because the chip dulls the tone of the recorded sound, it helps it to sit back in the mix much better, which enhances the illusion of two different players.
You're welcome to design a looper that satisfies all your criteria, just don't think of using a winbond chip. That's going to need some memory chips and some complex microcontrollers. Check out Manecloopers, then compare his products and you will see it's not really in the same league. It's like comparing a Ruby amp to a Flextone.
Yeah Pete, I spoke to Z about that a while ago after he posted his stuff. I understand the theory of doing it, but i'm not going to for two reasons.
Firstly, i'm not stepping on any more toes, and secondly I don't want to deal with all the noise problems it's going to create.
I think it would be easier to just design in an FX loop.
Title: Re: New Looper Design
Post by: The Tone God on October 27, 2005, 01:48:01 PM
From my reading I belive there is another cleaner way to vary the speed of the playback on the fly but it is not for the common DIYer. The power supply trick is kind of a hack but it works and is easier to impliment.

I attacked my looper design from the control angle instead of the audio. My looper splits the memory up into multiple banks for recording. It uses some really basic logic to do it. So you can turn that 60 seconds into four 15 second samples. It will work with any of the 25xx series so you can pick your time range if you wish.

I didn't finish my audio design but I went about that in a different way also.

Jaicen, do you have a schematic of this looper version handy ?

Andrew
Title: Re: New Looper Design
Post by: Jaicen_solo on October 27, 2005, 02:14:05 PM
I don't have a complete schematic as of yet, I basically laid out the design from the data sheets on the fly. I will produce one soon, but until then here's what I was working from:
http://www.winbond-usa.com/products/isd_products/chipcorder/datasheets/2560/ISD2560.pdf

I considered using the addressing logic in the chip myself, but apparently when you use any address other than 0 there's quite a large click at the beginning of playback. Something to do with it taking 25mS to address. Also, it seemed like a headache, so I won't bother!
Re: Playback speed, are you talking about modulating the external clock?? That supposedly causes some nasty audio aliasing if done during playback. Sounds nice to me, but I'm not going to make a hfo for it!
Title: Re: New Looper Design
Post by: The Tone God on October 27, 2005, 02:35:32 PM
My analog signal section used a small transformer on the speaker output to interface to the rest of the output circuitry. Most designs I have seen at this point spit the output into a opamp or something simliar which I think would account for everyone complaining about sound quality or various other issues.

I considered using the addressing logic in the chip myself, but apparently when you use any address other than 0 there's quite a large click at the beginning of playback. Something to do with it taking 25mS to address. Also, it seemed like a headache, so I won't bother!

The click is similar to the click at the end reset of the loop. I guess its a matter of taste. I came up with a quick and dirty way of addressing the logic needed. In the end I used a bunch of resistors, DIP switches / jumpers, two 4013s, a 4066, and two SPST momentary switches for bank select and playback/record. I also had a switch for selecting record / playback modes.

Re: Playback speed, are you talking about modulating the external clock?? That supposedly causes some nasty audio aliasing if done during playback. Sounds nice to me, but I'm not going to make a hfo for it!

Something in that space. As I said I don't think it is in the common DIYers space. I suspect that varing the power supply causes the clock to vary it's speed due to it's internal design.

Andrew
Title: Schem Up, Please Check
Post by: Jaicen_solo on October 29, 2005, 05:35:35 PM
Ok, here's the schematic for the mixer and input buffer of the looper. I'd really appreciate it if someone could check over the layout to make sure there are no errors etc.

http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZU4CYKo2nza5HKtWeCOJdPsORe2we8-3dK98ZclkL3xxOR9Wz-wct3WY2ANd_LNxfMoqHMwy7835DGlBkFBKGtdAUZNu6BnpeKaep6hHzVHRA

Edit: Pedal input connects to the 1uF/1M network on the non inverting input of IC1D. I forgot to label it, can't be bothered to fix. Off to bed now.  :icon_eek:
Title: Re: New Looper Design
Post by: Jaicen_solo on October 30, 2005, 10:15:14 AM
I've uploaded the complete layout and schematic to the link below. It's alos available as a pdf if you PM me. I can't host pdf's on this crappy MSN space.
Anyway, i've now modified it slightly so that it loops at address 0 which simplifies things slightly.
The layout also includes LED indicators for play-record, which I couldn't be arsed to add to the schematic.
Again, I forgot to add the input to the +'ve input on IC1D.
Is anybody excited by this design or is it just me?? Any feedback welcome!!!

http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUigaBFbBaI99ZruFzTGnnzoTv2V3NWx5DljRWDlQNcKI1j-06bhUhTZpUa8aB1uVCC6aDJBD8vEz25XsPikG3bTYKCdV3YTZAqrNAjRR_elw
Title: Re: New Looper Design
Post by: dr on October 30, 2005, 12:26:39 PM
kinda small and hard to read.....
Title: Re: New Looper Design
Post by: Jaicen_solo on October 30, 2005, 05:38:11 PM
edit: Previous layouts contained stupid errors, which hopefully have now been corrected.
Contact me via a PM for the new layouts, i'm not hosting them online anymore.
Title: Re: New Looper Design
Post by: Penguin on October 31, 2005, 02:41:29 AM
you konw not to step on any toes here but if you do a search you should come up with a long thread about the loop junky in which a few people mentioned the same chips that zack said he uses.  also there is a mention that i am reiterating now.  for expiraments theres a kit for under 25usd from circuit specialists that already has all the basic functions in it. and it gives 40seconds sample and loop.  as well as its already on a pcb board.  i haven't looked in about three months but when i played with one i was quite impressed took about an hour of wiring headaches to get the thing to loop andrecord with two TPdT switches.

Title: Re: New Looper Design
Post by: Jaicen_solo on October 31, 2005, 06:28:27 AM
Last week I found another of those kit's with PCB and layouts online. But that's not the point.
What you'll find is that those kits are operating in push button mode, which is not really needed for this application.
Also, I don't want to be hacking a commercial kit, which is likely to be using the mic inputs etc.. Not needed.
The design I want is just barebones looper with a high impedance input stage and mixer for the audio. If you buy one of those kits, you need to add an external mixer.
As for cost, in terms of parts I can build this for £15, of which £13 is the chip itself! But that's not the point. I'd rather build something myself which I can be proud of.

edit: I just found an ISD2532 chip, with half the record time, and half the price. Makes this a sub £10 project (in terms of PCB components, not switches and jacks etc). I also found a quad opamp designed to run on 6v, so that should work a little better in this application. Can't remember what it's called right now, but I'll try it at some point.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 17, 2005, 02:39:42 PM
Ok, below is a revised layout for this project drawn up in express PCB (much easier!).
I decided to use Bill Bergman's Analogue circuit, as it's known to work, if it isn't broke..
Digital circuit used is probably the same, though I haven't checked. I kept the digital half that I designed, so that the indicator LED's can be driven from transistors. My design also puts the ISD chip into standy when not playing, using the bypass switch, (Using a 3PDT Switch, the loop will start when the pedal is turned on, whilst still having true bypass). Connecting pads D & E will reset the pedal. 

Thoughts and ideas???

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZVGwupn6tA3kHjSC91r_FHRSr9wBm0VFHwpeXFHQpHJRcXe5LsEinJNqmiSuxqC-
AjSjLja8JoLUOFddQWBWYGciftN_zuNwNH2WKn5v6C75Q)
Title: Re: New Looper Design
Post by: Squeal on November 17, 2005, 09:30:14 PM
The circuit bending approach: rip the guts out of a children's toy with record/play function and make it go.
Title: Re: New Looper Design
Post by: robbiemcm on November 18, 2005, 12:38:30 AM
I'm really interested in this. All I think I really want out of a looper is the ability to record and play simple as that. Then what I would do is have an output jack for both the loop and then my guitar. This way if I wanted to add any effects to either one I could do that before recombining the signal and eveyrthing would be solved.
Title: Re: New Looper Design
Post by: nelson on November 18, 2005, 06:17:04 AM
full schematic?
Title: Re: New Looper Design
Post by: slacker on November 18, 2005, 08:07:00 AM
full schematic?
thats just what I was going to ask for. Looks like an interesting project.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 18, 2005, 09:06:31 AM
I'm really interested in this. All I think I really want out of a looper is the ability to record and play simple as that. Then what I would do is have an output jack for both the loop and then my guitar. This way if I wanted to add any effects to either one I could do that before recombining the signal and eveyrthing would be solved.

In that case, connect pin 2 of the PLAY pot to the hot pin of an output jack and you're sorted. You could even have the jack be a break socket, so that when nothing is connected, output goes to the internal mixer as per normal. The project will probably be updated to use a buffered effects loop at some point, I just couldn't find space on this particular board for that! (Although that's the whole reason for re-doing the layout in the first place!). Oh, and I put in a space for the LED/LDR control in the top left hand corner. This allows any variable resistance to ground to cause a pitch down effect. Could hook it up to an LFO for a vibrato effect as well.
I've done a couple of updates to the board, mainly moving components to more logical positions to make it more build friendly. Updates soon.
As for the schematic, I'll see if I can find the old digital schematic section. The analogue section is entirely Dean's design which can be found on generalguitargadgets.com. I added some light low pass filtering before the analogue-in pins (0.01uF/100k RC network). I figure since it's not going to record anything above 3kHz, I might get a better signal/noise ratio.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 18, 2005, 10:23:01 AM
Here's the complete digital schematic (I think it's complete at least!).  Whilst drawing it up I noticed a couple of errors on the PCB, so that will definitely need an update!
Voltage regultor is as per my optically variable design, that's on the schematic at the bottom. Using an LM317, voltage can be varied between +4.5v - +6v, should give plenty of pitchshifting action! ;) It would also be possible to just replace the LDR with a 16k resistor for a fixed 6v power point. That said, i'm not sure how that will affect the bias on the TL074, but it seems to work ok in Mathflan's Dirty sam.

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXOxuIiKfXbTdEs3ypSNY9gN2ZhYxM-
2QcLIdmqoZQcEqUJPoOL2XJw5FGIpX1Ff5gzF372DrsrFrdJktjwcJWRSChUj38xlK7Gqpu2NxA1bA)

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUdDnnGV0M4ZMpc0GLv1aby10GiNKa-K7ifEJOYLEJoPrup7dOPhhEnVvbWbQibvwqXTzbYeYuTesWgGYV6llfse2ea_Fq8FLYVZQ6Ch4yuIw)
Title: Re: New Looper Design
Post by: robbiemcm on November 18, 2005, 11:44:39 AM
Thanks so much for this Jaicen_solo it looks like a really good project. I will build this one when I feel I'll be able to pull it off succesfully, but to do it I'll need the ISD2560. And I'll get that when I go to England in a few weeks as I have no other means of getting here in Australia. I'll just build it as you made it as I would have no idea how to make the modifications you suggested for the ideas I had (I can only follow schematics, lol). Well.. I think I understood the part about using one of those jacks so that when one jack didn't have a lead in it the signal would just combine with the other one before the other jack. Anyway, thanks for the work you're doing.. I'm really excited about this one :)
Title: Re: New Looper Design
Post by: slacker on November 18, 2005, 12:45:31 PM
cheers for the schematic, I've put this on the to build list, might make a nice project to start the new year :)
Title: Re: New Looper Design
Post by: Jaicen_solo on November 18, 2005, 04:12:45 PM
Thanks guys, I like to feel i'm giving something back after my many years of learning :)

Robbiemcm, if you're coming to the UK, search out a Maplins store. Since there's one in my home town, I tend to create projects which use components they stock. I'm leaning toward getting an ISD2532 rather than a 2560 as it's about half the price. It's also half the record time, but I can't see me needing more than 30s anyway. All in, it's possible to get this project together for about £10-15 depending on what caps and things you buy. The board is spaced for mini-electrolytics in the psu filters (+1 ceramic beneath the ISD chip), and Mylar caps in the signal chain. All the resistors are 1/4W, spaced to 0.4 inches. Makes things a whole lot easier when populating if everything can be bent to shape beforehand, and I find mylar caps to be reliable and good sounding.I recommend getting a Header socket for the ISD, which will allow you to add the small ceramic bypass cap beneath the chip itself. If not, it can always be soldered to the traces side. Actually, it might not even be necessary, but I am paranoid about noise in this circuit!
If all goes well, i'm going to get all the components together for my build this week. I'm looking forward to some hardcore looping action by next saturday! ;)  If there are any mod's you'd like to see included then let me know, i'll see if I can work them into the schem. I'm certainly going to try for an FX loop, if I can find room for some in/out buffers.

One final thing to note, is that the LFO section on my variable regulator is taken from Tim Escobedo's site; Circuit Snippets. I think it's a nice neat design, Thanks Tim!
Title: Re: New Looper Design
Post by: robbiemcm on November 18, 2005, 11:36:52 PM
Well, to be honest I really think it would be a great feature to have to two seperate output jacks, and then if one isn't connected they just combine at the other one. Is it as simple as connecting the wires together or do you need weird buffers or 1M resistor across blah blah blah (I have no idea what I'm talkin about now). If you think about it it would be great to have the output going through whatever pedal you desire, for example I expect many people will require a different sound to the backing chords if they want to solo over the top. And if that feature was there then you wouldn't really need that vibrato thing would you? You could just chuck in another pedal.

Also, I think I found the right chip at a place closer to home for a cheaper price than you can get from England.
http://www.futurlec.com/     Then in the search, type ISD2560
Is that the right chip? It seems to fit the right specs and it's also about the same price as the one with less recording time that you speak of. The only confusing thing about that is 60 - 120 seconds? Does that mean it has a minimum recording time? That wouldn't make sense.. either that, or it'd be annoying to be required to record for 60 secs..
Title: Re: New Looper Design
Post by: nelson on November 18, 2005, 11:58:48 PM
Just ordered the IC.


Should be fun messing with this.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 19, 2005, 12:31:03 PM
Robbiecm, that is indeed the correct chip. The record time is quoted as a minimum, as it can be increased by changing the sample rate. Power supply voltages affect the internal clock, hence the pitchshifting. That's also why the play speed decreases.
As for price, I just found the ISD2560 and 2532 at RS components, for £8 and £5 respectively, so i'll probably get a 60 for three squid difference.
I'm going to leave the voltage regulator design in I think, you can just use fixed value resistors if you don't want pitching effects. It will work just as well.
It also occured to me that since you'll need a dpdt play/record switch, I could just dispose of the transistor circuitry and run the indicator LED's directly via the switch. Much easier build that way, and eliminates about 10 components.
I'll work on adding the effects loop this weekend, should hopefully have a final revision on monday. Till then, don't build anything as nothing is verified!
Title: Re: New Looper Design
Post by: Jaicen_solo on November 19, 2005, 02:12:45 PM
Here's something for you guys to be getting on with; a Mobius Lite.
This version of the schem has no effects loops etc, just a straight single sample looper. Record/play LED's are driven from the other half of the Record/Play DPDT stompswitch to save board space, which is down to 2.7" square. I think it would be hard to make it any smaller (The ISD Chip is 1.4" Long!!) The indicator led in the top right pulses at the end/start of each repeat, but can be omitted if not necessary.
The reset pins should be connected to one pole of a 3PDT switch, so that it starts from the beginning of the sample whenever it is engaged. If you want, this can also be omitted so the loop will play continuosly, however this cuts current draw to just 10mA when not in use (as opposed to 30mA when playing). Pin A should be held high by connecting to pin B when the pedal is bypassed.
Other mods that could be added include a tone control, such as a 0.02uF cap from Play pin1 to pin 1&2 of a 100K pot, with pin 3 to ground. This will allow you to dial in some heavy treble cut on the loop, but not the direct signal.
This is intended to be a less daunting build than the other loopers out there, i'm hoping more people will want to build this layout for it's simplicity, especially those new to these things. Everyone should have a looper for practice and songwriting :) Let me know your thoughts guys, I'm starting work on my Deluxe Mobius now ;)

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUC65AofDuofJs6c6MlNRObBeHB2SVJaqvnjrnKFbxdTzxtRXn1H10ThObxZcF8CD8SQbpLqDOTVbUJ4Pmz1YMFJ4jOgrQmopdnuawcUK8_ng)

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXNvPglwQGQAa_vWTuoGNtzYBIQgXg5hFe4aaiNerI8JrnsgcDBx0YAIjjnG1e-TDOg1Z_PdkbT8LrhD3JtR60MAwi00z1fCoSsPGSOpIhMWg)
Title: Re: New Looper Design
Post by: nelson on November 19, 2005, 03:12:59 PM
Great work man.

I am going to wait for the Dlx version, also perhaps you should change the name?

I am going to reiterate a request for a full schematic.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 19, 2005, 03:46:00 PM
Cheers Nelson!
I agree, i'll build the deluxe myself, probably both actually! I just thought it would be nice for a less advanced stompboxer ;)
Below is a layout i've just cobbled together for the deluxe version, which features pitchshifting, effects loop and tone control, in addition to the regular features. Schematic is to follow shortly when i've got it all drawn out neatly. I find them more work than layouts to be honest, though I usually spot any errors when drawing the final schem up. Let me know if you spot any errors. The effects loop i've added is just a buffered loop using a TL072, biased as per the TL074. Mix In & Mix Out should be connected together, though they could be connected to a toggle to send the mix to another output as per RobbieCM's suggestion.


Components:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXMfTulYB20pk4IVhAnEF6iluEMlIF-CBrd9LZt1l7ljAOtXV1yg7TqHrXIVWLFnRuiHy9lfcxdOWVuZ9OOZBzZHxdErQHd_o-R9RfCQnQBkw)

Traces:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZWxHUPM48dk5Mu2Zpy86UJampXEO2YWJjaDAxSnnHqYwhVX7ZcoidC1782ECDQBTr1NUJBRmvvwOrAxpl2rt66GehlQFTC6DL4MOrP4ls_zaQ)
Title: Re: New Looper Design
Post by: robbiemcm on November 19, 2005, 09:54:28 PM
Thankyou so much for the work you've done Jaicen, I hate to think how many hours of work you must have put in to come up with all of this. However, I'm pretty new to this whole thing (although I'm getting there steadily) I might need some assistance in figuring out what to do with the two outputs and everything. The Mobius Lite looks perfect for me, it doesn't have too many extra features like the Deluxe. It'll be far easier to start off with I suspect rather than varying voltages and such.

I must ask this though, is the record button the same as the play button? So it engages as soon as you finish recording? And wouldn't it be good to have a stop switch aswell? What happens when you don't want it playing in the background anymore? Then the reset would become a sort of play/reset.
And also I see the A,B,C parts for the switches, am I right in thinking that that corresponds to one pole of a dual throw switch? B being the input and A and C being the two throws?
With the Lite version, there is just a straight output. Is it possible to divide the guitar and the loop output on that version? If you can show me where to pull the two from I can probably take it from there :)

Once again, thankyou so much for the work you're doing
Title: Re: New Looper Design
Post by: slacker on November 20, 2005, 07:35:36 AM
I must ask this though, is the record button the same as the play button? So it engages as soon as you finish recording? What happens when you don't want it playing in the background anymore?

If I understand it right you press the record/play switch to start recording then press it again and the pedal plays what you've just recorded. The effect also has a seperate true bypass switch, so if you don't want to hear the loop you bypass it, when you engage the pedal the loop starts playing from the beginning.

This leads me to a couple of questions though. Will the pedal actually work with this switching system? I only ask because the data sheets talk about pulsing the CE Pin low to start/pause the play or record operation, on the schematic above the CE is tied low all the time.
Also I think that if you record for the full duration of the chip it won't loop, and you'll have to start play manually, which may or may not be a problem, just thought I'd mention it.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 20, 2005, 08:18:52 AM
The CE pin only needs to be pulsed if the chip is operating in momentary push button mode. In this design, it's operating on levels, when CE is held low all the time to enable play and record. If CE goes high, everything stops! It is possible to add a pause mode, by taking the CE pin high during record/play. I might add that to the deluxe layout if you guys think it would be useful (can't see it myself though).

The design of the 25xx series now means that there's no longer an OVF or overflow pin. Previously this was used to reset conditions or for cascading multiple chips. With the new chips, if you reach the end of the record time, it will just stop and wait and begin looping as soon as you hit play. If you record a full 60s, it will still loop when it reaches the EOM marker.
If you don't want the pedal to go straight back into play mode when you engage it, just click the bypass switch before you hit the play switch. That will put it into standby mode (thus ending the recording), ready to begin looping when you hit bypass again. If you were really fussy about it, you could just wire up the reset pins to a second latching on/off switch and use that to start and stop things.
Robbiecm, you are correct about the switch wiring. B is the center pole of a SPDT, or one half of a DPDT.
On the deluxe layout, Mix out is the output of the ISD chip, buffered by the effects loop. Effects are wired to the FX send and returns. Mix out needs to be connected either to the MIX IN connection, to use the mixer in the circuit, or it can be wired to a seperate output. In this case, you can omit the fx send/returns. If you don't want to use the FX loop, just connect PLAY pin 2 to the MIX IN on the layout and omit the TL072 and associated components.
On a related note, I found a website somewhere where one of these loopers had been built with a pair of chips, each recording the same thing. They can then be pitchsifted and generally messed with to make some really interesting chorus/flanging and general dischord.  :icon_twisted: Nice!
Title: Re: New Looper Design
Post by: robbiemcm on November 20, 2005, 11:03:59 AM
Sorry Jaicen, I still don't quite understand what I need to do in order to get the two seperate signals. I tried tracing it backwards referring to one componenet layout, one trace layout and the deluxe layout but that didn't end up doing me any good. And surely it would be best to just use the Lite version? That currently has everything I want except the two seperate outputs. Is it possible to do it with the Lite version, or are they not combined via traces and combined inside a chip making it impossible for me to to it like that.

It seems as though they *could* be from those 100k resistors connected to a cap, then to output, but I wouldn't know. I'd take a guess that saying the lower 100k resistor is the clean guitar signal? Maybe you'd be able to indicate on you schematic where each seperate one is before they are recombined (if it works like that) and then I'm assuming all I'd have to do is chuck a 10uF capactior from those outputs to my jacks? Or would I choose a different value when taking two seperate signals.

Thanks for putting up with me,
Robbie
Title: Re: New Looper Design
Post by: Jaicen_solo on November 20, 2005, 01:44:05 PM
It's actually pretty simple Robbie, once I get a schematic up you'll be kicking yourself ;)

There are basically two paths for the signal, one goes from the input buffer to the input of the ISD, the other takes the output of the ISD, buffers it and feeds it to the mixer stage, which mixes signal from the input buffer, in with the ISD signal.
To Isolate the output of the ISD, wire up the PLAY pot as per normal, but take the wire from the center pin of the pot to wherever you want it to go (ie, seperate out jack) instead of the PLAY2 pad on the PCB. The wiper of the play pot normally connects to the mixer circuit, but if you do this, you'll just get the clean signal from the buffered input at the output of the PCB.
Does that help??
EDIT: How's this?

(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZVfOes_-uXd8vEyNb8ADA1yYZVK0IGAVKi2Xtb2fP-WVU08787UKTmSnZ5JnbckhIStu9U9fxJJZo6QScn7frVpOXBDrCBDv-E3xNXjZ3m1ug)
Title: Re: New Looper Design
Post by: Herr Masel on November 20, 2005, 02:46:37 PM
Am I the only one that gets a blank page when I click the links for the layout?
Title: Re: New Looper Design
Post by: Jaicen_solo on November 20, 2005, 04:51:59 PM
The old layouts have been removed, they had a few errors. The new layouts should all be embedded into this thread.
Don't build anything yet, I've fixed a few errors on them today.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 20, 2005, 07:16:50 PM
Ok ladies and gentlemen, i'm ready now to unleash my looper on the world at large ;)
Below is the PCB and parts layout for my deluxe looper. Since this is quite far removed from the Mobius, i've re-named it Lazarus for reasons I'd think obvious ;)
I'll draw up the schem tomorrow, but i'm fairly sure that it's 100% correct. I've been over the layout a number of times and fixed a couple of errors.
I do need to re-arrange the rectifier on the Mobius Lite i've already posted, as the pinout is wrong. The top two pins need to be reversed, and there's an error on the biasing of the TL074.
The PCB needs to be printed at 300dpi, should be sized to 3.9"x2.7" (97.5x67.5mm for you europeans and modern englishmen like myself ;) )
As always, thoughts and suggestions welcomed.

edit: New revisions posted below.
Title: Re: New Looper Design
Post by: robbiemcm on November 20, 2005, 07:18:08 PM
Alright, I think that makes sense. So the wiper of the Play pot goes to a capacitor and then to an output jack. And that's the loop play. The other signal will be coming from the output which already has a capcitor there? And when I recombine the signals later, do I need any special buffers or something?
Title: Re: New Looper Design
Post by: Jaicen_solo on November 20, 2005, 07:28:15 PM
Yeah, you probably will need to recombine the signals using some sort of buffer. There's no way to know how different pedal combinations are going to react when passively combined. Particularly if one or more is bypassed.
To be honest, I think you might be better off building the Lazarus, as it it has everything you seem to be needing all on one board. It's not that much harder to build either, though the wiring is slightly more complex. I've uploaded a wiring diagram for the Lazarus, have you seen it??
Title: Re: New Looper Design
Post by: robbiemcm on November 20, 2005, 11:53:42 PM
Hmmm.. I still like the idea of the Mobius Lite for my ideas. It would allow me to change the sound of both the loop and the straight up guitar signal. For example, if I wanted distortion on the guitar signal I wouldn't have to have it on the loop aswell. It can't be that hard to build some form of special circuit with a buffer purely for recombining the signals can it? Wouldn't I use the same principles as you except I would just be doing mine in a seperate box.

And just wondering this..
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZVfOes_-uXd8vEyNb8ADA1yYZVK0IGAVKi2Xtb2fP-WVU08787UKTmSnZ5JnbckhIStu9U9fxJJZo6QScn7frVpOXBDrCBDv-E3xNXjZ3m1ug)
So the green wire off the pot is the loop out and what was originally the combined out is now straight guitar out?
Title: Re: New Looper Design
Post by: Jaicen_solo on November 21, 2005, 07:59:01 AM
So the green wire off the pot is the loop out and what was originally the combined out is now straight guitar out?

Yeah, you got it now. Like I say, you'll need some sort of buffer to recombine them. I see where you're coming from now. I think R.G. has schematics for a splitter/buffer. There's certainly one at GGG.
One thing on a similar vein i'd like to note is that i've inserted trim pots onto my lazarus board, to fine tune the send/return volumes of the effects loop. You might want to try something similar.
Title: Re: New Looper Design
Post by: robbiemcm on November 21, 2005, 09:34:05 AM
Ahhh... isn't that what the play volume pot is for, you know.. the one I'm taking the loop output from? As for straight guitar I suppose it would be easy enough to chuck a volume pot onto that output.

One thing I've always wondered with volume pots. Is it okay to have that final cap before the volume pot, or is it better to have it between the volume pot output and the output jack?
Title: Re: New Looper Design
Post by: Jaicen_solo on November 21, 2005, 10:08:42 AM
Yeah, you can use the play pot for a master volume control, but you might find that the signal coming out of your effects varies in strength, so I added the option of decreasing the gain somewhat at both the send and return. That way i've covered all the bases so to speak.
Usually with volume controls, you want the cap on the wiper, that is going back into the circuit. That will protect the output from any scratchy DC which might be getting onto the pot. I'm not sure how much difference it makes putting it before the pot, but that's the way I try to do things.

Anyway, here are the layouts and PCB's for both versions of my Looper. The schem is also shown, which is the same for both versions, except for the effects loop.
I'm going to say they're complete for now, unless anybody spots any errors, I'd appreciate them being checked.

MOBIUS LITE:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUbuBeDG6woyy28s72eaAkv03ox7LQiBcZin2ameLwc9OaT6Hmzfj8k4x1kagbjASKVOPWvtOU2U36JaHTmX0fL01NXOxtOa5k4DzAyRtLp4A)

MOBIUS LITE PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX6SESjwA3D6y3KDVajujt1-ByxgdAJgp3o9rO1COnKa_vFXW5O7HjLINoT85d4dj9254-WlbJZlTrCXFfxWwwYEIEB6yQikj68ZD4bXxO0Lg)

LAZARUS LAYOUT:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXTlkRdJ1qAdlJWR3B8RTaac0-_zUDgWOvqyXDbLbAIVDkiLEZxUIfUZEjOW6l6p9T4yD3sG6SF8LWAZxqPVM9hg4ZlvABXe3c_Bp0FAOMl5A)

LAZARUS PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZWygAHRdVj0H5L13zhKJqOlJChC9Wm81_TLohGVH67dqI3YAuGta2NU_UFWyArz4dszI2yzoRqoIANR7BYwvoJn3IUvvqwg9YvQT1VBtekbfQ)

LAZARUS SCHEMATIC:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX-FyY-eqTRb7DdyPRTeHJOd_oIcHD0MUXwsPPBtmjOAOaGjZDdjsEVSzi83COUOIofbzx3M78SqglQsIrSsiyR9pLmRmt_Zxd0nINEOV-S6g)

DIGITAL SCHEM:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUi0LdR40KIp33N79tFg7z3nYyhO_H-8NXwAPx4rrAhc6MzNaYWsILFW6DW8KFuBeEG5HQCd9PLlkkKjadC4nzHeWCp4exBGmLe0TvlZ2jLKA)
Title: Re: New Looper Design
Post by: robbiemcm on November 21, 2005, 11:16:30 AM
Well done on getting those complete, Jaicen. It must have taken alot of hard work, so thankyou. I was looking for the TL074 and LM317 and I seem to have found myself a few different types. Are they all pretty much the same? Some seem to be double the price of others? Maybe you can help distinguish between them..

TL074: Search for it on www.futurlec.com it has two possibilities

LM317: http://www.altronics.com.au/index.asp?area=item&id=Y0926
http://www.altronics.com.au/index.asp?area=item&id=Z0545

I can get all the other components easily, but I'm just not sure which of those are suitable.

Thanks once again, hopefully I'll be building this beast some time over the summer holidays (chances are it'll have to wait til after I get back from England).
Title: Re: New Looper Design
Post by: Jaicen_solo on November 21, 2005, 02:45:21 PM
It wasn't really all that much work, but thanks! ;)

You can get an LM317 from Futurelec for $0.45, that should work fine. The second of the accutronics rectifiers should work fine too. Don't spend too much either way. 100mA is more than enough for this project.

The TL074 you can use just about any 14pin DIP package. At futurelec you want the TL074CN, which is the one I use. The CD is surface mount, which would make life pretty difficult for you ;)
I'm getting all the components I need to build mine tomorrow hopefully. I'll keep you updated.
Title: Re: New Looper Design
Post by: Herr Masel on November 21, 2005, 03:35:26 PM
Thanks for your work. I would like to build a looper but I'm having trouble finding the ICs for the pt80 delay so I don't know if it will be possible, unless I have them shipped from far away..
Title: Re: New Looper Design
Post by: Jaicen_solo on November 21, 2005, 04:09:14 PM
Well Herr Masel, i'm not sure I fully understand your question. The PT80 is not used in this project, it's a delay chip. Going by your name, i'd guess you are German, or at least european. In that case, look up your local RS-Components, who will have an ISD25xx in stock. This is the chip you'll need for this looper project.
Title: Re: New Looper Design
Post by: mathflan on November 21, 2005, 05:54:34 PM
fantastatic work jaicen!
glad to see your looper's works finished.

I have  a question about your FX loops schematics..
But How is it works without Effect in the FX loops, Do the Play pots fuction??
On the dirtysam, it uses Jack with CLosed circuit...
Title: Re: New Looper Design
Post by: Jaicen_solo on November 21, 2005, 06:34:36 PM
Thanks mathflan!

Yeah, the FX loop works with a break jack on the send just like the Dirtysam. basically, Send is connected to Return unless a jack is inserted into the send socket. When this happens, the connection is broken, and the signal goes out to the external loop, and back into the FX return via the Return socket.
I guess you could add a DPDT switch to toggle the FX loop on and off too. Play pot controls the loop volume wether an effect is in the loop or not.
Title: Re: New Looper Design
Post by: mathflan on November 21, 2005, 08:33:07 PM
ok, but I'am asking if is it good that the signal pass trough two Opamp ?? when you don't plug jack into FX loop...
For Me I thought that when you don't plug jack in FX loops,  the center of the PLAY and the Resistor 33k are connected directly??

Title: Re: New Looper Design
Post by: domenico on November 22, 2005, 06:57:43 AM
hi ,
some months ago I've tried those schematics from isd's web site and I've found that if you don't use a circuit similar to http://humano.ya.com/guruzeta/Guitarra/dirtysam/digital.html you will have huge pops when pressing record/play switchs
domenico
Title: Re: New Looper Design
Post by: robbiemcm on November 22, 2005, 11:32:18 AM
Tell us how it goes Jaicen, it will be interesting to see if these pops are present like domenico suspects.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 22, 2005, 12:28:06 PM
Hey domenico, thanks for your input. Would you care to share the schematics and/or designs you were working with?
To be honest I don't see why there would be pops, since the CMOS circuit is doing pretty much the same job as mechanical switches.
There was some discussion between Zvex and a few others about the Power Down feature causing thumps when the chip is turned on again. Apparently it has something to do with the input impedance of the amp they're connected to. I'm not too sure, but we'll soon see if it's a problem!
Mathflan, that was something that didn't occur to me actually! I guess it would be easy enough to do, just a case of wiring things up differently. I don't suppose it makes a heap of difference to have the signal buffered again, it's non inverting and low gain, but I'll give it some thought.
Title: Re: New Looper Design
Post by: domenico on November 23, 2005, 03:30:19 AM
I don't know why,  but the isd25xx series make pops when switching from record to play or when resetting the chip using mechanical switch.

as I can see the pop is a common problem on isd devices , read this
http://www.winbond.com/c-wINBONDHTm/partner/PDFresult.asp?Pname=593 ,
http://www.laserforums.com/forum/archive/index.php/t-313.html ,
http://www.winbond.com.tw/e-winbondhtm/partner/b_2_a_4_d.htm
or search on google : isd2532+pops

The only thing I know is that I've solved the problem using a digital circuit similar to dirtysam's one , try it !
Title: Re: New Looper Design
Post by: robbiemcm on November 23, 2005, 11:07:08 AM
Hmmm.. I got this off the laser website that Domenico linked us to..

(http://danhalloween.250free.com/sound.jpg)

That seems to be an incredibly simplified version, or is that one not at all suitable for what we intend ours for? I read that the better a circuit is designed, the less audible the pops will be. And considering that abrely has any caps I'm going to assume you'd get some big ones, also I've read about not having caps at the output lets DC in to your amp or something.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 23, 2005, 11:29:23 AM
That is a pretty simplified version of what i've built.
The schematic shown there will not loop, only playback once and go back to the start.
I can assure you i've waded through all those pages and more. I read all the technical articles at winbond too, including those for the other chip series' such as the 3300 etc.
Like i've said before, the popping sound us usually caused by the chip coming out of power down mode, and there's not really much that can be done about that if you want the looper to start from the beginnine each time it's bypassed. Even the Lo-Fi loop junky has this problem with certain amps. I'm driving the output of the chip differentially, so hopefully that will help somewhat. I've also applied loads of filtering to the power supply!
Title: Re: New Looper Design
Post by: domenico on November 23, 2005, 11:32:08 AM
I've tried this too...sorry it pops the same...listen to me , use a 4070 ic based circuit to control the isd25xx play/rec/stop/start/

this one will work : http://humano.ya.com/guruzeta/Guitarra/dirtysam/digital.html

domenico
Title: Re: New Looper Design
Post by: robbiemcm on November 23, 2005, 11:41:04 AM
You seem to have it very well sussed out Jaicen, do you think you will be able to make us some audio clips of it when you have finished making it? Or do you not have the setup at home to be able to do that?
Title: Re: New Looper Design
Post by: slacker on November 23, 2005, 11:58:46 AM
I guess the only way to find if it pops is to build it :)
If the pop is casused by a DC offset on the inputs as the chip powers up like one of the links domenico posted suggests then you may be able to cure it by biasing the ana in pin to half the chips supply voltage.
If you do end up having to use logic to control it then at least you might be able to use the other 5 invertors from the 40106 on your wobbly power supply.
Title: Re: New Looper Design
Post by: Jaicen_solo on November 23, 2005, 12:28:58 PM
I'm a sound engineer by trade, so I imagine I could knock up some decent enough recordings ;)

The whole point of the ISD25xx series was to simplify control by allowing push button or edge control. I find it strange that they would deliberately design an IC for this that is unsuitable for it's purpose! How exactly does using a mechanical switch cause popping, excepting self noise?  I don't see where it would come from, since the control circuit is seperate from the analogue signal.
I plan to get all the components to build mine this week, so I'll probably build it on sunday/monday. If I do have problem's I can't fix, I may consider inverter control, but in that case, I may as well build the dirtysam! The point of this was to build a looper with the simplest possible configuration.
Title: Re: New Looper Design
Post by: slacker on December 03, 2005, 07:40:52 AM
Any news on this yet?
Title: Re: New Looper Design
Post by: Jaicen_solo on December 03, 2005, 01:44:22 PM
As of yet, i've not had time to work on anything stompbox related at all. I work in a shop and we're getting the christmas rush, so it's all hands on deck at the minute. I'll let you know as soon as any progress is made.
Title: Re: New Looper Design
Post by: nelson on December 08, 2005, 09:47:49 PM
Got my chip all ready too build this. I hope it works and I dont have to start trawling through datasheets and design one myself.

If you want this all wrapped up nicely in a PDF project file jaicen send the stuff to me once its verified and I will tie it all together.
Title: Re: New Looper Design
Post by: robbiemcm on December 08, 2005, 11:55:39 PM
Good work Nelson make sure you give us all a detailed summary of how it went when you're done. Out of interest, do you think you'll be done in the next few days or will it take you a while? I'm off to England in 3 days, but I suppose I will be able to check back here at my cousin's house.
Title: Re: New Looper Design
Post by: Zak Mc Kraken on December 09, 2005, 09:28:28 AM
Hi,
I ve just read the datasheet, and to avoid popping, the ISD must be in push button mode. But in this mode, it is said that the chip powers down after each playback. So you don t have the loop function.
Is it right ?
Title: Re: New Looper Design
Post by: Jaicen_solo on December 09, 2005, 05:15:36 PM
You can loop whilst in OP mode if you keep address pin 4 high.
Whilst in OPmode, the chip can be level or edge activated, so you can either use latching or momentary switches for operation.
This layout should in theory allow either to be used. I still haven't had time to build mine, i've been working late shifts all week, sucks big time!  :icon_cry:
Title: Re: New Looper Design
Post by: kissack101 on December 27, 2005, 04:25:59 PM
hey,

at the risk of sounding like a kid on holiday... any news on if this works or not? I was watching this thread unfold back in October with some amount of anticipation of a cool lo-fi looper and then it all went a little quiet...

Adam.
Title: Re: New Looper Design
Post by: Jaicen_solo on December 27, 2005, 06:34:49 PM
Once again, I must apologise. I guess since this is my baby I should be the first to build it  :icon_lol:
I've just not had a lot of time with this being the holiday period (I've got a temp job in a shop, sucks). As soon as I build anything, you guys will be the first to know!!
Title: Re: New Looper Design
Post by: robbiemcm on January 06, 2006, 12:37:33 PM
Just keeping this topic alive to see how the building is going, Nelson seemed to state that he had the bits ready to go.. so I was wondering whether he ever got round to it?
Title: Re: New Looper Design
Post by: Jaicen_solo on January 08, 2006, 09:32:07 PM
Just a quick note to let all those that are following this thread know that I haven't forgotten them ;-)
Having been sacked from my temp christmas job I have a little extra time on my hands so hopefully I should have some results for you all pretty soon.
If all goes to plan, at least one looper will be finished (and hopefully working) by the end of the week.

Title: Re: New Looper Design
Post by: galad on January 09, 2006, 10:45:20 PM
hi, just registered but i've been reading this and the other posts on loopers
and i would like to try to build one too

i only know a few things about electronics, although i did build a fuzz pedal

i've got an answering machine i've been messing around with, although i don't think it has an isd25xx

it'd be great if you could post some really basic looking schematics when you're done
Title: Re: New Looper Design
Post by: nelson on January 10, 2006, 03:08:44 AM
Waiting for the verification that this thing doesnt pop, then the board will be etched populated and enclosed before you can say polly want a cracker.
Title: Re: New Looper Design
Post by: robbiemcm on January 11, 2006, 04:51:28 PM
Mmmm, on my holiday in England I've been thinking about just how much I want to build this project, I can't wait! This will be the first project I build when I get back, providing I think I can cope with it. Make sure you take some photos while your building it to give us a nice look :D
Title: Re: New Looper Design
Post by: kissack101 on January 26, 2006, 06:52:50 AM
...any word yet? I got paid more than I was expecting today and this cool piece of kit has been on my agenda for a while. Unfortunatly, my limited abilities means i'm probably not the pioneer required to see if the thing works. Just keeping the thread alive, many thanks to all those doing the leg-work...
Title: Re: New Looper Design
Post by: robbiemcm on January 26, 2006, 08:53:08 AM
Yeah, I'm not really up to the task of building this thing to tell you guys whether it works or not. The chances I will do something that makes it not work that is no fault of the circuit is about 90% so chances are I would come back saying it doesn't work even if the circuit is perfect  :-[
Title: Re: New Looper Design
Post by: robbiemcm on January 31, 2006, 04:28:59 AM
Galad, here's the schematics and all for the looper:

MOBIUS LITE:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUbuBeDG6woyy28s72eaAkv03ox7LQiBcZin2ameLwc9OaT6Hmzfj8k4x1kagbjASKVOPWvtOU2U36JaHTmX0fL01NXOxtOa5k4DzAyRtLp4A)

MOBIUS LITE PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX6SESjwA3D6y3KDVajujt1-ByxgdAJgp3o9rO1COnKa_vFXW5O7HjLINoT85d4dj9254-WlbJZlTrCXFfxWwwYEIEB6yQikj68ZD4bXxO0Lg)

LAZARUS LAYOUT:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXTlkRdJ1qAdlJWR3B8RTaac0-_zUDgWOvqyXDbLbAIVDkiLEZxUIfUZEjOW6l6p9T4yD3sG6SF8LWAZxqPVM9hg4ZlvABXe3c_Bp0FAOMl5A)

LAZARUS PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZWygAHRdVj0H5L13zhKJqOlJChC9Wm81_TLohGVH67dqI3YAuGta2NU_UFWyArz4dszI2yzoRqoIANR7BYwvoJn3IUvvqwg9YvQT1VBtekbfQ)

LAZARUS SCHEMATIC:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX-FyY-eqTRb7DdyPRTeHJOd_oIcHD0MUXwsPPBtmjOAOaGjZDdjsEVSzi83COUOIofbzx3M78SqglQsIrSsiyR9pLmRmt_Zxd0nINEOV-S6g)

DIGITAL SCHEM:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUi0LdR40KIp33N79tFg7z3nYyhO_H-8NXwAPx4rrAhc6MzNaYWsILFW6DW8KFuBeEG5HQCd9PLlkkKjadC4nzHeWCp4exBGmLe0TvlZ2jLKA)
Title: Re: New Looper Design
Post by: slacker on February 02, 2006, 08:37:44 AM
I've ordered the chip for this. My plan is initially to put something simple together just to see if the switching scheme works, then move on from there. I'll post results as soon as I've got some.
Title: Re: New Looper Design
Post by: Jaicen_solo on February 02, 2006, 08:43:16 AM
I'm going to go get the chips for mine this afternoon if they have any in stock.
Hopefully I can finally get this damn thing built!!

Title: Re: New Looper Design
Post by: slacker on February 03, 2006, 04:04:30 PM
I've got a stripped down version hooked up on my breadboard. At this stage I haven't bothered with the analogue side of things I've just got an opamp buffer on the ana in and Sp+ for input and output. Unfortunately unless I've missread the schematic and wired it up wrong the switching doesn't work. It is entirely possibly I've got the theory behind the switching  wrong so  here's what I think is supposed to happen.
PD is low to enable the chip, if PR is high it will play back until you put PR low when it should record then putting PR high again plays back what you've just recorded.
Unfortunately simply switching the state of PR doesn't work. If it's playing and I put PR low it just stops playing, if it's recording and I put PR high then it carries on recording. The only way I can make it change what it's doing is to pulse PD high after I've changed the state of PR. For example if it's recording I have to put PR high then pulse PD high to make it start playback.
Like I said hopefully I've done something wrong or misunderstood the switching.
On the plus side it doesn't seem to pop coming out of a powered down state and the sound quality's pretty good .
 
Title: Re: New Looper Design
Post by: Jaicen_solo on February 03, 2006, 06:25:12 PM
Thanks Slacker, I guess I let the switching scheme get away from me somewhat. I think you do have the theory correct, unless i've forgotten something.
As it stands, I think you'll probably need three switches if you want true bypass. Originally i'd planned to wire Play/Record to one half of a DPDT switch, with the second half wired to the reset pins. Connect the center of the reset pin to a 100K resistor to ground, and the two contacts to Vcc. If the switch is a break-before-make type this might allow PD to be pulsed enough to reset, restarting playback. If not, I guess you'd need to have a bypass switch and a reset switch.
To be honest, I'm confused as to how Zach's design is able to record whilst in the bypass mode if it's still true bypass. I can't see how it's done with just two switches.

I'm not entirely sure why the chip doesn't immediately begin playing when switching P/R from low to high. According to the datasheets that's all it needs, however you could try adding the indicator LED's and transistors connected to the P/R and EOM pins. I have a feeling this might provide a low going pulse to reset the state once recording is finished.
I'll do a little more research and let you know tomorrow, i'm a bit rusty on right now.
BTW, I had to order my chip online as my local maplin didn't stock the 2560, surprise surprise, so that's put back my efforts somewhat.

Title: Re: New Looper Design
Post by: slacker on February 03, 2006, 07:01:39 PM
Thanks Slacker, I guess I let the switching scheme get away from me somewhat. I think you do have the theory correct, unless i've forgotten something.
Connect the center of the reset pin to a 100K resistor to ground, and the two contacts to Vcc. If the switch is a break-before-make type this might allow PD to be pulsed enough to reset, restarting playback.
Yeah I'd had that thought I'll give it a try.
Quote
To be honest, I'm confused as to how Zach's design is able to record whilst in the bypass mode if it's still true bypass. I can't see how it's done with just two switches.
It's not true bypass, the mod to allow recording in bypass mode basically leaves the input connected when bypassed, it's explained somewhere on his site. Presumably the pedal doesn't stop looping when you bypass it.

I'll try hooking up the LEDs and see if that helps. If not I'll try and figure out how to trigger a pulse, shouldn't be too hard and the design will still be simpler than the dirty sam.



Title: Re: New Looper Design
Post by: Jaicen_solo on February 03, 2006, 08:55:31 PM
It also occured to me that you might have it configured in the wrong operational mode. Are you following the digital schem posted here? If not, which address pins are going to ground??
Title: Re: New Looper Design
Post by: slacker on February 05, 2006, 09:40:09 AM
yeah I've got the address/mode pins connected like in your digital schematic.
Title: Re: New Looper Design
Post by: slacker on February 06, 2006, 04:23:23 PM
well I played around with this all day yesterday, nursing a hangover I might add, and I've come up with a switching solution that works. It uses a couple of gates of a 40106 to pulse the PD pin and one to select play/record, just to debounce the switch. It's fairly simple and the other gates can be used to switch the LEDs.  If no one has any luck with a switch only method I'll post  a schematic.
Title: Re: New Looper Design
Post by: robbiemcm on February 22, 2006, 06:48:59 PM
Slacker: how did this turn out for you? Do you think there could be a chance of some audio clips if you get the chance :D

Thanks in advance,
Robbie
Title: Re: New Looper Design
Post by: slacker on February 23, 2006, 08:07:59 AM
It's still on breadboard at the minute, because I was waiting to see if Jaicen_solo had any luck getting his original system to work. The switching I've done works fine but I'm still playing with the audio side of things. I'll post my switching schematic and try and do some sound clips.
Title: Re: New Looper Design
Post by: robbiemcm on February 25, 2006, 11:15:50 AM
Slacker: with the switching scheme you are using, can you do it with only 2 switches or do you need a third?
Title: Re: New Looper Design
Post by: bond on February 26, 2006, 04:01:09 AM
bump

any progress anyone?
Title: Re: New Looper Design
Post by: slacker on February 26, 2006, 07:11:05 AM
Slacker: with the switching scheme you are using, can you do it with only 2 switches or do you need a third?

It works with 2 switches same as Jaicen's design. One of them is a true bypass that also resets the loop to the start when you engage the pedal. The other switch is play/record.
Heres the play/record switching schematic, like I said it's still a work in progress but it works.
(http://www.eskimo.plus.com/fxstuff/looperswitch.png)
Title: Re: New Looper Design
Post by: Jaicen_solo on February 26, 2006, 07:27:47 AM
Slacker, that's a really neat and elegant solution to the switching problem. I'm thinking that a layout for that should be included with the project files as a daughterboard, or maybe even integrated into the existing layout since it's only a single 14-pin dip that shouldn't be too hard.
Title: Re: New Looper Design
Post by: slacker on February 26, 2006, 07:42:39 AM
cheers, feel free to add it to the project files. I've got no PCB design software, I'm strictly a vero man, so I'm afraid I can't help you out with layouts.
I take it you haven't managed to get the switch only method to work then?
Title: Re: New Looper Design
Post by: bond on February 27, 2006, 04:48:45 AM
mmmm i'm gonna order the parts an the 40106 chip, and breadboard it and try get it to work...
Title: Re: New Looper Design
Post by: bond on February 27, 2006, 10:41:57 PM
why is ther a LDR on the board?
Title: Re: New Looper Design
Post by: Jaicen_solo on February 28, 2006, 07:27:25 AM
The LDR is used to vary the supply voltage going to the chip. It's a bit of a dirty hack but it should allow for some vibrato. Using the values I've calculated gives the maximum swing in voltage between min and max.
I'm starting to feel like an absent father to this project a bit. I really haven't had time to get anything together lately. Many thanks to Slacker and all those that have kept this thread alive.
Title: Re: New Looper Design
Post by: robbiemcm on March 01, 2006, 11:30:59 AM
Heh, don't worry I'm sure I'll be keeping it alive until I decide I can safely start my project, then drive you mad wondering why the hell it doesn't work.
Title: Re: New Looper Design
Post by: Jaicen_solo on March 01, 2006, 11:38:16 AM
Thanks Robbie!
It just occured to me that i'd originally designed the LDR to be paired with an LED driven from a 40106 oscillator. The oscillator's not my design it's from Tim's PWM design, but I think i'll resurrect it to use up the remaining invertors from the switching schem!
Title: Re: New Looper Design
Post by: robbiemcm on March 02, 2006, 11:47:45 AM
Alright, I've decided I'm going to go ahead and get the bits to build this. Slacker obviously has a switching scheme that works, and I figure by the time I get around to building it myself we will have at least one finished version. It'll also be easier than anything out there, and I know where to get help directly from if I have any questions.

Also, when browsing on futurlec it appears as though I have the choice of 60, 90, or 120 sec chips. the 90 and 120 are both $10.51 but the 60 is $11.90  ... why would the ones with more recording time be cheaper? Is there a loss in sound quality for these ICs? And does the P at the end of ISD2560P mean anything that I have to take not of, or will that chip be fine.

Robbie
Title: Re: New Looper Design
Post by: nelson on March 02, 2006, 02:19:58 PM
I still have all the key parts for this in my bins, waiting for it to be verified. I had given up on this and was going to do my own design. But the momentum is building again, so I will wait.

I think I got the 120 second chip.
Title: Re: New Looper Design
Post by: bond on March 02, 2006, 10:22:37 PM
mmm i've given up ...
decided i will sell something and buy a really good one like an rc-20 or jamman
i think building a pt80 and univibe should keep me feeling good inside for the next few months

really want to be able to overdub ...
mmm i could build two of these an hook them up together, but buying one that has voice in it + save loops mmmmmmm (reverse to me just sounds ugly)
Title: Re: New Looper Design
Post by: robbiemcm on March 04, 2006, 04:08:37 AM
I'm sticking with, I don't really know any place you would be able to buy a looper like this. Other than ZVex, but that's like $500 and I expect I would get this right before the 5th time round building it, and end up with a similar product. Minus the awesome painting.
Title: Re: New Looper Design
Post by: bond on March 04, 2006, 05:15:27 AM
http://www.digitech.com/products/JamMan/JamMan.htm

gonna buy myself a jamman.


for more:
http://www.loopers-delight.com/tools/tools.html
an for some interestin clips:
http://www.loopers-delight.com/files/

also a really good example is from 4:00min on of:
http://www.howieday.com/live_site/video/sorrysosorry_bwryvidfull_300.asx
Title: Re: New Looper Design
Post by: A.S.P. on March 04, 2006, 05:59:51 AM
E-H 2880 Multitrack Looper (scroll down) (http://www.musictoyz.com/guitar/pedals/eh.php)
or 16 Second Delay (scroll down further...)
Title: Re: New Looper Design
Post by: bond on March 04, 2006, 08:06:41 AM
mmm in all the reviews i've read, the jamman is rated superior until the boss RC-50 comes out ....
the eh16sec is more catered to the studio
Title: Re: New Looper Design
Post by: robbiemcm on March 05, 2006, 08:50:09 PM
The JamMan is so bulky it looks like it's basically a computer that you're feeding your guitar into, and I much prefer building stuff myself. The path is clear for me, I'm sticking with this one :D
Title: Re: New Looper Design
Post by: bond on March 06, 2006, 12:45:15 AM
for what it can do, its terrible small, 17cm*14cm
considering a 1590bb is 9.4cm*12cm it really on doubles in width
99saved loops something like 6hours of recorded tracks
overdub, reverse, can do guitar+mic+aux at the same time.

the only thing that will beat it will be the boss rc-50 but thats a whole pedalboard.
Title: Re: New Looper Design
Post by: robbiemcm on March 10, 2006, 10:41:15 PM
I think I'll get the 60 second chip, I don't see how the ones with more storage time can be cheaper unless they sound worse. I'd look at the data sheets to find some differences but I have no experience reading them and have no idea what to look for, nor what they would mean.
Title: Re: New Looper Design
Post by: ethrbunny on March 10, 2006, 11:55:28 PM
What are the chances of PCBs being made?

Do any of these designs let you turn on / off the playback without starting a record cycle?

IE play -> record/play -> play + playback -> play -> play + playback

does that make sense?

Title: Re: New Looper Design
Post by: slacker on March 11, 2006, 07:15:36 AM
Not quite sure what you mean but here's how it works. You've got 2 switches play/record and bypass.
Play/record switches between play and record so if the unit's playing and you press the switch it starts recording. If it's recording and you press the switch it plays back what you've just recorded.
The bypass switch is true bypass that also stops the unit when it's bypassed. So if you want to stop playback you press the bypass switch, when you press the bypass switch again it engages the effect and starts playback from the start of the loop.  You can also change play/record whilst it's bypassed.
I'm thinking of adding a toggle switch to give a mode that wouldn't stop the unit whilst it's bypassed. The loop would carry on playing in bypass mode, but you wouldn't hear it. Then when you engage the effect the loop would be playing where ever it is in the cycle. This might be quite useful for more ambient sounds.
Title: Re: New Looper Design
Post by: ethrbunny on March 11, 2006, 10:05:30 AM
On the cheesiest level - imagine the chorus to a song. Angels weeping, cherubs singing, etc etc. You have pre-recorded this magical moment in your looper. You only want it to play during the chorus and then hush up. You want a switch to start the playback from its beginning. The same beginning every time.
Title: Re: New Looper Design
Post by: slacker on March 11, 2006, 10:15:18 AM
yes it will do that, the starting at the begining part that is I don't know if it will manage choirs of angels :)
basically put it in play mode, then press bypass which puts the loop back to the start and bypasses the effect. Then when you want to kick in the chorus press bypass again and the loop starts from the begining. At the end of the chorus press bypass again the effect shuts up and the loop goes back to the beginning.
Title: Re: New Looper Design
Post by: ethrbunny on March 11, 2006, 10:45:55 AM
Niiiiiice. Will it keep looping indef or just 1x?
Title: Re: New Looper Design
Post by: Jaicen_solo on March 11, 2006, 11:11:13 AM
Well, by definition it has to loop to be a looper ;)

It would be quite easy to add a switch that will pause the looper at any point, allowing it to resume at that point. From memory I think you have to take the CE pin high for pause and low for play, but i'd have to check the schem to be sure.
Title: Re: New Looper Design
Post by: ethrbunny on March 11, 2006, 11:30:58 AM
Ok. Ive been wanting to build one (another) of these. I have 2 of the 120 chips and lots of the parts still stuck to my semi-functional Gurutheta box... not to mention a nice box that needs to be used. I can track down another few sockets and give it a whirl.

EDIT: where is the latest spec for this new(er) design? Sounds like its still in the mod phase.
Title: Re: New Looper Design
Post by: robbiemcm on March 12, 2006, 12:12:22 PM
If a circuit designer had a lot of time on their hands could they make it be able to record over the top of one recording by using two chips, and simply playing one and combining its output and the guitar into the other one?
Title: Re: New Looper Design
Post by: puretube on March 12, 2006, 01:25:07 PM
 :icon_wink:
Title: Re: New Looper Design
Post by: The Tone God on March 12, 2006, 02:03:57 PM
If a circuit designer had a lot of time on their hands could they make it be able to record over the top of one recording by using two chips, and simply playing one and combining its output and the guitar into the other one?

Its possible but it will not be very smooth. Remember that tick at the end of the loops ?

Andrew
Title: Re: New Looper Design
Post by: puretube on March 12, 2006, 04:51:57 PM
exact that`s the reason for using (crossfading) 2
(this was frowned upon, a short while back...)
Title: Re: New Looper Design
Post by: robbiemcm on March 14, 2006, 04:19:09 AM
Wait.. am I reading this correctly? You have to mke it play first, and only then can you record. So you'd press play/record it starts playing, press again it starts recording, press again it stops recording and starts playing..? :-\
Title: Re: New Looper Design
Post by: slacker on March 14, 2006, 08:12:15 AM
Wait.. am I reading this correctly? You have to mke it play first, and only then can you record.

No you don't have to make it play first before you can record. When the effect is on, it either plays or records so if it's doing one and you press the play/record switch it does the other. If you want it to start recording without playing first, then you start with it bypassed which stops the unit doing anything, then you select record using the play/record switch. then press bypass to engage the effect and it starts recording, when you want to play press play/record again.
It basically works the same as the zvex loop junky.
Title: Re: New Looper Design
Post by: The Tone God on March 14, 2006, 08:21:39 AM
exact that`s the reason for using (crossfading) 2
(this was frowned upon, a short while back...)

Well that adds a new level of complexity.

The IC does not respond instantly either so there would not a be a smooth time transistion processor to processor. It would eventually lead to weird time problems as oppossed to a smooth delay.

Andrew
Title: Re: New Looper Design
Post by: nelson on March 14, 2006, 12:03:29 PM
exact that`s the reason for using (crossfading) 2
(this was frowned upon, a short while back...)

Well that adds a new level of complexity.

The IC does not respond instantly either so there would not a be a smooth time transistion processor to processor. It would eventually lead to weird time problems as oppossed to a smooth delay.

Andrew

Well mr almighty, alighten us with a new design.


(http://cdn-cf.aol.com/se/clip_art/peeps-emt/pple/clips/notworthy-clip)

If you deem us worthy to receive thy blessing.
Title: Re: New Looper Design
Post by: hank reynolds 3rd on March 14, 2006, 12:54:03 PM
Miaow pussycats !!!  ;D

<IMG SRC="<a href="http://www.phatpimpclothing.com/pimpmyspace_codes.html">
<img src="http://i32.photobucket.com/albums/d49/chuskins/@#$%youcouch.gif" border="0" alt="@#$% Yo Couch" /></a><center>hosted @ phatpimpclothing.com</center>">
Title: Re: New Looper Design
Post by: hank reynolds 3rd on March 14, 2006, 12:54:25 PM
dammit...that didn't work
Title: Re: New Looper Design
Post by: nelson on March 14, 2006, 01:08:42 PM
Miaow pussycats !!!  ;D

<IMG SRC="<a href="http://www.phatpimpclothing.com/pimpmyspace_codes.html">
<img src="http://i32.photobucket.com/albums/d49/chuskins/f*ckyoucouch.gif" border="0" alt="f*ck Yo Couch" /></a><center>hosted @ phatpimpclothing.com</center>">

(http://www.phatpimpclothing.com/hi/phatpimp/images/sm_vid_rickjames_slap.gif)


No HTML tags :)
Title: Re: New Looper Design
Post by: A.S.P. on March 14, 2006, 01:13:26 PM

pimpin`ain`t easy...
 (http://www.phatpimpclothing.com/pimpmyspace_codes.html)
Title: Re: New Looper Design
Post by: hank reynolds 3rd on March 14, 2006, 01:24:23 PM
<a href="http://www.phatpimpclothing.com/pimpmyspace_codes.html">
<img src="http://i32.photobucket.com/albums/d49/chuskins/@#$%youcouch.gif" border="0" alt="@#$% Yo Couch" /></a><center>hosted @ phatpimpclothing.com</center>
Title: Re: New Looper Design
Post by: hank reynolds 3rd on March 14, 2006, 01:24:41 PM
aaahh ,f**k it....
Title: Re: New Looper Design
Post by: A.S.P. on March 14, 2006, 01:36:47 PM
(http://photobucket.com/albums/d49/chuskins/f*ckyoucouch.gif)

?
is it it?
?

animated.gif (http://photobucket.com/albums/d49/chuskins/f*ckyoucouch.gif)

parental advisory:  explicit picture!

replace the asterisk in the URL by a " u " ...  after accessing the page
Title: Re: New Looper Design
Post by: slacker on March 14, 2006, 03:57:49 PM
you want stupid pictures? I'll give you something really stupid.  ;D
(http://aronnelson.com/gallery/albums/slackers-stuff/looperboard.png)
yes kids an untested vero layout of the looperchip and switching system, I don't need no stinking PCBs  ;D
Title: Re: New Looper Design
Post by: The Tone God on March 14, 2006, 08:12:29 PM
I'll see your Rick James and raise you the big guy.

(http://img.photobucket.com/albums/v515/TheToneGod/the_big_lebowski_jesus.jpg)

Don't fuzz with The Tone God!

Seriously I wish I had a design to offer but I don't nor any advice to help do what your asking. From the playing around I did with these ICs I don't belive it is possible to make some kind of decent delay out of it. Its just the wrong technology kind like the first Matrix...

(http://img.photobucket.com/albums/v515/TheToneGod/dot_matrix.jpg)

Andrew
Title: Re: New Looper Design
Post by: nelson on March 15, 2006, 08:37:46 AM
"Dont F*ck with the Jesus"


I love that movie.
Title: Re: New Looper Design
Post by: Jaicen_solo on March 15, 2006, 08:53:44 AM
Hey slacker, you getting in on the action here?
Now I remember why I hate veroboard! I'll be knocking up a layout for your switching scheme soon.
I'm really seriously gonna build this soon, I promise.....(yeah yeah you say.. ::)).
Title: Re: New Looper Design
Post by: robbiemcm on March 15, 2006, 10:05:43 AM
you want stupid pictures? I'll give you something really stupid.  ;D
(http://aronnelson.com/gallery/albums/slackers-stuff/looperboard.png)
yes kids an untested vero layout of the looperchip and switching system, I don't need no stinking PCBs  ;D

And we don't need no education, but overall it's better if we do have one.
Title: Lazarus Indeed!
Post by: Jaicen_solo on May 18, 2006, 08:59:11 AM
Hey guys, talk about bringing threads back from the dead!
I've been spurned into action today by the recent 4x15s looper project which was just posted. I've now got what I consider to be the definitive Lazarus Looper project ready to go, though I'd appreciate it getting the once over by those in the know (Slacker, i'm talking to you!).
The layout now includes the Schmitt switching system designed by slacker, as well as the LFO vibrato system i'd devised (read, copied from Tim's PWM design ;) Thanks Tim ). I decided not to use the buffered effects loop, as it was taking up too much space for how useful it was. I figure anyone building this will have the skills to make an input/output buffer on a bit of perf or something. I think a round of applause is well deserved for the switching scheme, which is very elegantly done. I'm sure I would have come up with something far more complicated and less good. Big thanks also to Bill Bergman for the nice analogue design.

Anyway, as ever thoughts and opinions welcomed.

Oh, and the PCB artwork should print out at 4.4x2.7" @ 300dpi. (It's reversed ready for PnP).

(http://f5.putfile.com/5/13708465893-thumb.gif) (http://putfile.com/pic.php?pic=5/13708465893.gif&s=f5)

(http://f5.putfile.com/5/13708463088-thumb.jpg) (http://putfile.com/pic.php?pic=5/13708463088.jpg&s=f5)
Title: Re: New Looper Design
Post by: slacker on May 18, 2006, 01:40:49 PM
Cool glad to see your looper's still alive. Thanks for the comments about my switching idea :)
I'll have a look at the PCB but it's not any area I'm too familar with, see the vero monster above :D
I really hope someone finally gets to build this.
Title: Re: New Looper Design
Post by: Jaicen_solo on May 21, 2006, 08:44:10 AM
I think I was a bit hasty releasing that last layout, there are a few areas that needed to be changed.
I've taken out pretty much everything that doesn't need to be in there now to keep the PCB small. As I said before, it's only 4.4 x 2.7, which is small, but not BB small!
Anyway, i'm basically saying don't build this layout yet it's not finished!
Title: Re: New Looper Design
Post by: robbiemcm on May 24, 2006, 11:28:12 AM
Yay, new development on it. I havn't checked back here in a while, but it's good to see I came back not too long after your update. I think I'll make this raw version before trying to make an effects loop one, I've only ever built two pedals (one unsuccessful attempt, same problem twice.. most likely a grounding issue that I don't know how to fix). And for that reason aswell, and effects loop won't be particularly useful. I aim to get the bits for this project in 6 weeks when I have two weeks holidays, so I'll give it a shot :D
Title: Re: New Looper Design
Post by: The Tone God on May 24, 2006, 02:00:31 PM
Since there is no schematic and I'm too lazy to trace it how are you doing the "vibrato" ? I put alittle thought into it and I think I came up with a nice clean solution but I wondering if you did something similar.

Andrew
Title: Re: New Looper Design
Post by: Jaicen_solo on May 24, 2006, 02:49:11 PM
Good to hear you're still up for it Robbie ;)

The vibrato effect is a bit of a dirty hack really. I'm basically using a variable voltage regulator, with an LDR modulating the output voltage. I'm sure there are easier ways to do it, but that's just the solution I came up with as the LDR will give the maximum swing from +4 to +6v. At values higher or lower the chip wont function, so at least this way it will never lock up.
Title: Re: New Looper Design
Post by: The Tone God on May 24, 2006, 03:58:37 PM
The vibrato effect is a bit of a dirty hack really. I'm basically using a variable voltage regulator, with an LDR modulating the output voltage. I'm sure there are easier ways to do it, but that's just the solution I came up with as the LDR will give the maximum swing from +4 to +6v. At values higher or lower the chip wont function, so at least this way it will never lock up.

Hmm...I can see some advantages and disadvantages to that.

My idea was to use some clocked power regulator IC, probably a charge pump, that would take an external clock source like say the 7660/1044. I would clock the charge pump with a derivitive of the Vanishing Point v2.1's random mode. The HF clock would clock the charge pump set to the correct frequency. The HF clock would be modulated by the second clock only it's rate of modulation would be controlled with a pot. The depth of voltage modulation could be done several ways. It would get rid of the LDR and provide a fairly consistant voltage swing range through out the battery life. It would also be easy to reproduce once the part values were calibrate.

Just a few thoughts. I haven't looked at this circuit for some time.

Andrew
Title: Re: New Looper Design
Post by: robbiemcm on May 25, 2006, 06:59:45 AM
I'm looking forward to building this, plus a vibrato would be a nice addition.. providing it had rate + depth pots, but I'm sure that's standard in this world ::)
Title: Re: New Looper Design
Post by: Jaicen_solo on May 25, 2006, 07:07:21 AM
Yes there are indeed rate and depth pots provided on the layout, i'm sure it wouldn't be much use otherwise!
With regards to the charge pump, I did consider that but decided against it for two reasons. Firstly, they have a tendency to introduce whine through the power rails, to which the ISD series is particularly sensitive. Secondly, it would require a more complicated & stable external oscillator.
In theory, regardless of the battery voltage, the regulator should always swing by the same amount though I understand that theory is not always the reality. To be honest, I only use external PSU's now so I find myself less and less concerned about battery life vs features. 
Title: Re: New Looper Design
Post by: robbiemcm on May 25, 2006, 07:19:43 AM
Heh, my 9v PSU (old phone charger) died recently. I get nothing from it when it's plugged in, I assume it's because I just left it plugged in the whole time and due to the regulator that was across the rails it was trying to pump out power for about 3 months without ever beind turned off.

Would you mind pointing me to this thread with the other looper, I pwomise I'll build yours ;) I'm just interested, and I couldn't find it in my short spammings around. Do you think this looper will be classed ready for the build in 6 weeks time ;D
Title: Re: New Looper Design
Post by: Jaicen_solo on May 25, 2006, 07:29:44 AM
I'd say it's probably ready to build now, I'm just a little busy this week so I won't be able to verify the layout till next monday probably.

The other thread is here: http://www.diystompboxes.com/smfforum/index.php?topic=45313.msg331710#msg331710
At the minute, i'd hold off on building it until it's been successfully prototyped. Dr Ron tells me that he's already modified the layout to use a new switching scheme also.
That said, it would be a relatively easy task to interface Dr Ron's loop selector control to the Lazarus layout i've made, perhaps using a seperate board containing all the switching. All that would then be needed is to cut two traces on my board, and replace them with jumpers to Ron's board. In all other respects, the loopers are going to be pretty much the same. However, I do believe that addressing the ISD chip introduces clicks into the start of the recordings due to the nature of the storage technology, so that could be problematic. Like I said before, best to hold off until a prototype is working.
Title: Re: New Looper Design
Post by: nelson on May 25, 2006, 09:16:47 AM
I still have the chip for this in my collection.

I am waiting for a schematic to be published before I build it.
Title: Re: New Looper Design
Post by: robbiemcm on May 25, 2006, 11:01:47 AM
It's good to see I'll have a nice 2 week holiday project to encourage me to rip my hair out.
Title: Re: New Looper Design
Post by: The Tone God on May 25, 2006, 01:52:49 PM
I eventually get back to my design so I will give that feature another shot as I did not really play with it before. I still think the output section could be improved as well. Ah so little time.

Andrew
Title: Re: New Looper Design
Post by: robbiemcm on May 28, 2006, 12:36:25 AM
Have you had the chance to make a prototype yet? I'd love to hear what it sounds like ;D
Title: Re: New Looper Design
Post by: The Tone God on May 28, 2006, 02:40:07 PM
Have you had the chance to make a prototype yet? I'd love to hear what it sounds like ;D

Is that directed at me ? If so I did do some work but I never finished the output section as I spent most of my time with control section (i.e. using the address inputs for multiple loops and other things.) To me the output is the biggest issue with pretty much every looper I have seen. I have some ideas of how to solve it but need to find some time to play with it again. Before I ever release something to the public I always like to make sure it works by building it so to that end I will won't post anything until I'm confident of its performance.

Andrew
Title: Re: New Looper Design
Post by: slacker on May 28, 2006, 05:51:27 PM
To me the output is the biggest issue with pretty much every looper I have seen.
I've seen you mention this before, I was just wondering exactly what the problem is with the output?
I'm only asking because I've put one together, based on Jaicen_solo's design, but with simplified input and output stages and I can't see a problem.
Title: Re: New Looper Design
Post by: The Tone God on May 28, 2006, 06:48:20 PM
I've seen you mention this before, I was just wondering exactly what the problem is with the output?

I didn't experience any issues but I was using the IC to drive a speaker as per it's intended design since I was focusing on the control section. I have seen many reports of people complaining about the output quality being fuzzy, low, noisy, etc. I personally think this is because trying to drive an opamp input using a circuit that was designed to drive a speaker might not be the best way to do it. Just theory on my part. When I get back to the circuit I test this out and see if there is a solution if need be.

Andrew
Title: Re: New Looper Design
Post by: robbiemcm on May 28, 2006, 10:27:23 PM
Have you had the chance to make a prototype yet? I'd love to hear what it sounds like ;D

Is that directed at me ? If so I did do some work but I never finished the output section as I spent most of my time with control section (i.e. using the address inputs for multiple loops and other things.) To me the output is the biggest issue with pretty much every looper I have seen. I have some ideas of how to solve it but need to find some time to play with it again. Before I ever release something to the public I always like to make sure it works by building it so to that end I will won't post anything until I'm confident of its performance.

Andrew

Sorry for the confusion, it was originally intended for Jaicen but it was open for anyone else that was building it ;D I look forward to hearing how it goes.
Title: Re: New Looper Design
Post by: slacker on June 01, 2006, 05:20:22 PM
If anyone's interested here's a couple of soundclips of my looper prototype, it's based on Jaicen's design but with a simpler audio side that I put together to test my switching idea.
The first sample is a prerecorded loop with some frankly dodgy lead playing on top. The second loop starts with guitar, with a loop recorded and played back on the fly. There's a bit of switch click but this doesn't get recorded by the loop. The looper's on 2 boards with some pretty long leads and it's not boxed up, hopefully thats why the click's there.
prerecorded loop (http://www.eskimo.plus.com/fxstuff/looper1.mp3)
on the fly recording (http://www.eskimo.plus.com/fxstuff/looper2.mp3)

Title: Re: New Looper Design
Post by: The Tone God on June 01, 2006, 05:56:14 PM
I have just started work on my own looper design. I'm designing from scratch not that I am saying anyone's design is bad just that this is usually what I like to do.

I don't know if it was my particular IC or something in the family (25xx) but the thing popped BADLY when entering and leaving power down. I have solved the power up/down output pop problem now and the IC output interface issue. I think I have a much better way to do the vibrato then I previously thought as well. I will hopefully be adding a number of new features too.

Andrew
Title: Re: New Looper Design
Post by: domenico on June 09, 2006, 11:47:43 AM
tonegod says : "The IC does not respond instantly either so there would not a be a smooth time transistion processor to processor. It would eventually lead to weird time problems as oppossed to a smooth delay."

yes it's true and now is my problem ! I've built a looper with isd2564 with slacker design control and when I switch from record to play the chip cuts some notes at the begin of the sample , what's wrong???
thanks
domenico



Title: Re: New Looper Design
Post by: Jaicen_solo on June 09, 2006, 11:51:01 AM
When you say it cuts some notes, do you mean it doesn't record the first bit of the loop?
There is a small (few millisecond) latency inherent in the design of the chip, but this shouldn't be audible.
Are you sure you've got the IC wired correctly?
Title: Re: New Looper Design
Post by: The Tone God on June 09, 2006, 02:23:06 PM
yes it's true and now is my problem ! I've built a looper with isd2564 with slacker design control and when I switch from record to play the chip cuts some notes at the begin of the sample , what's wrong???

When we use the IC just as a plain recorder the time it takes the IC to come out of power down, latch the mode/address and P/R inputs, set the address pointer, configure the needed modules, and start the function should still not take that long so I don't think this is the fault of the IC.

I assume you are using the inverter based digital circuit. Just looking at that design I think the delay is coming from the large debouncing network on the gate inputs for the PD pin. You could try to tweak the values to speed it up but you could get issues if you set it to fast.

I have finished the preliminary digital logic design for my looper which I designed from scratch. Here some of the highlights.


Yes a non-optocoupler based vibrato is on its way (I hope) and the output pop issue seems to be worked out. As of this time the audio section will probably be fairly simple too.

Enough about this. I don't want to hijack the thread and I have to get back to work on it anyways.

Andrew
Title: Re: New Looper Design
Post by: slacker on June 09, 2006, 03:41:30 PM
yes it's true and now is my problem ! I've built a looper with isd2564 with slacker design control and when I switch from record to play the chip cuts some notes at the begin of the sample , what's wrong???

When we use the IC just as a plain recorder the time it takes the IC to come out of power down, latch the mode/address and P/R inputs, set the address pointer, configure the needed modules, and start the function should still not take that long so I don't think this is the fault of the IC.

I assume you are using the inverter based digital circuit. Just looking at that design I think the delay is coming from the large debouncing network on the gate inputs for the PD pin. You could try to tweak the values to speed it up but you could get issues if you set it to fast.

I'd agree with that. According to the datasheet the ISD2564 only takes 50 milli seconds to power up, this is longer than the ISD2560 that I tested with but it's not long enough to cause any problems. How much time are you losing at the start of the sample? My switch probably takes a few 10ths of a second to switch so if you're losing more than that your problem is not with the switching. You can try making the 2 2.2uF caps smaller, this will speed up the time taken to switch.
While doing the samples I posted I did notice it was quite tricky to get a nice smooth loop going, but I couldn't decide whether it was a technical issue or my bad timing :) I'll take another look at the design and see if I can improve it.
Or you could wait for The Tone God's looper thats bound to be good :)
Title: Re: New Looper Design
Post by: domenico on June 10, 2006, 10:54:57 AM
hi thanks for the replys , I've tried 1mf cap with no results...should I replace 2564 with 2560 ?
thanks
domenico
Title: Re: New Looper Design
Post by: The Tone God on June 10, 2006, 02:21:31 PM
Or you could wait for The Tone God's looper thats bound to be good :)

Thanks for the vote of confidence. :)

hi thanks for the replys , I've tried 1mf cap with no results...should I replace 2564 with 2560 ?

I am using a 2575 which I have little if any trouble with start delay and the difference in times between the 2564 and 2675 is roughly 10-15ms which I think is probably not enough to make a difference in performance.

One thing I will make note of the 2564 is it has a low cut off frequency (1.7kHz) and low sampling rate (4.0 kHz). If you want to get performance similar to the 1420 (6.4kHz sampling and 2.6kHz cutoff) I would go with either the 2540 (6.4kHz sampling and 2.7kHz cutoff) or the 2575 (6.4kHz sampling and 2.7kHz cutoff).

While all that extra time sounds like a waste I am hoping to give my looper the ability of multiple loops so the extra time won't be wasted. Oh and I got the vibrato working. :)

Andrew
Title: Re: New Looper Design
Post by: zachary vex on June 11, 2006, 12:22:07 AM
october '05 till now... sounds like my development cycle for the lo-fi loop junky!  8^)  actually, it was a couple of years because i kept putting it aside and trying new things after a few months of letting it sit.  at one point i completely gave up on it, but in the end, i had several important breakthroughs including discovering how to eliminate popping at the output.  or most of it, at least.  8^)
Title: Re: New Looper Design
Post by: The Tone God on June 11, 2006, 06:35:41 PM
Roughly one dozen DIY members + nearly a year = 1 Zachary Vex

;)

Andrew
Title: Re: New Looper Design
Post by: zachary vex on June 12, 2006, 04:18:05 AM
your challenge, of course, will be to fit it on a circuit board .88" wide by 3.6" long.  8^)
Title: Re: New Looper Design
Post by: The Tone God on June 12, 2006, 04:30:45 PM
your challenge, of course, will be to fit it on a circuit board .88" wide by 3.6" long.  8^)

Hmm...well if I don't include every feature I am going to suggest in the article I think I can do it. I sir accept your challenge. :)

Andrew
Title: Re: New Looper Design
Post by: nelson on June 12, 2006, 08:34:47 PM
Tiny caps, 5 layer board, resistors standing, 9mm pots: NO PROBLEM.



Title: Re: New Looper Design
Post by: The Tone God on June 13, 2006, 03:20:55 AM
Tiny caps, 5 layer board, resistors standing, 9mm pots: NO PROBLEM.

5 layer board, nah. Not worth the time and expense of doing a PCB just for a one-off lark. I'll perf it. I'll have to do some CADing to see what pots I can fit in there but I figure I can fit five easily maybe six if I'm careful. I have a bunch of other dirty tricks that I can use as well. :)

Andrew
Title: Re: New Looper Design
Post by: domenico on June 13, 2006, 09:13:42 AM
now my looper works ! It mounts a 2560 chip with slacker control and a bypass/reset switch .
the looper records and plays in time only when after a recording you reset the looper with bypass/reset
switch
to play the loop you have to set the looper in play and to hit the reset/BYPASS SWITCH
the problem of notes cutting remains when after the recording you set the looper on play without resetting it with  reset/bypass switch
bye!
Title: Re: New Looper Design
Post by: zachary vex on June 14, 2006, 12:22:09 AM
i did it with only two sides, but i had to use heavy copper to eliminate noise issues.  keep that in mind.  8^)  hey, doesn't my lo-fi loop junky do everything on your list except go for longer than 20 seconds?  i guess the way i got it to fit on that small board was by not needing a logic chip... the family i used has enough on-board logic to use simple discrete component tricks to make it do what i wanted.  i always wanted a longer looper, though... good luck, tone god!  8^)
Title: Re: New Looper Design
Post by: The Tone God on June 14, 2006, 03:06:26 PM
hey, doesn't my lo-fi loop junky do everything on your list except go for longer than 20 seconds?

On that list yes. I will be hopefully including a few other features as mods like a phase switch for the recorded output so if you play along you can get a different chorus effect. The big feature I hope to get working is the multiple loops as that is one the big reasons why I went with the 25xx series. I have a few other minor features I want to play with.

The controls on my current looper are also more extreme. The vibrato can for example slow down the playback to the point of almost stopping, but not reseting the IC, without causing too much added time to the loop. It sounds like a record starting up. The loop input and output volume controls also have more so the IC's input can be overdriven or the output could overdrive other effects/amps. There is also a final output control so one could mix the loop and dry signal to their tastes.

i guess the way i got it to fit on that small board was by not needing a logic chip... the family i used has enough on-board logic to use simple discrete component tricks to make it do what i wanted.

I took a quick look through the other family datasheets and I can see why it would be alot easier to use one of those. Those families are really optimized for pushbutton operation where the 25xx series is trying to cater to both pushbutton and uC needs. To do that they removed some of the internal logic and exposed more of the internal controller's inputs and outputs. For this reason I have generate some of the logic externally to get back the functionality. In the end it has only taken three gates, three resistors, and two caps to do the logic.

While I'm probably losing space with the external logic I'm probably getting some back in other areas. For example I'm using the last gate as the clock to drive the vibrato. Besides using a unused gate to save space I can add the feature that the vibrato will be automatically disabled during recording and enabled during playback. I also can do a power down / true bypass trick using only a DPDT switch with the addition of only one part.

The other big problem is that if I'm going to do multiple loops I need access to the address pins which mean I can't use any of the internal operational modes. Hopefully I can get the loops to work so that as you are in the middle of one loop's playback you can select another loop and when the current loop reaches the end, or you cycle the bypass switch, it will jump to the selected loop allowing different phrases to be stored.

The logic took me a couple of days to get working right. I could have grabbed a uC and done it in minutes but that would be cheating. ;) If I had decided to go with a uC I would have grabbed one the other IC families and done some really cool stuff. The output portion ALOT easier too.

i always wanted a longer looper, though... good luck, tone god!  8^)

Thanks Mr. Vex. :) I haven't done a small build awhile so this should be fun.

Anyways back to work.

Andrew
Title: Re: New Looper Design
Post by: robbiemcm on June 21, 2006, 08:02:06 AM
Good to see this topic has come back to life.

Tone God: yours seems really interesting, and you certainly have a lot of really good features lined up for it.. all of which I can see as being useful. Please don't sacrifice these features in order to cut down on the size though, I know I personally would rather something can do even just a little more a few extra centimeter of floor space. I intend to build yours if I survive Jaicen's looper first ;D
Title: Re: New Looper Design
Post by: The Tone God on June 21, 2006, 02:36:59 PM
Tone God: yours seems really interesting, and you certainly have a lot of really good features lined up for it.. all of which I can see as being useful. Please don't sacrifice these features in order to cut down on the size though, I know I personally would rather something can do even just a little more a few extra centimeter of floor space. I intend to build yours if I survive Jaicen's looper first ;D

I guess I'll give a little bit of an update. The circuit is finished, tweaked, and works as expected. I have a rough schematic drawn and the article is partially done. I got all the extra features working including the multiple loops. I am content with it.

I'm not going to be offering a PCB so the size thing is not an issue. I made the decision awhile back that for now on I will only give the basic schematic with a functional explanation and some mod suggestions. From there people can decided what they want to do.

The size challenge is only a silly little thing on the side that I am doing for fun. I would not inflict those restrictions on other builders. As for the challenge I am not concerned about getting the basic version in there. The only question is how much more can I fit in there which the answer according to my design is just alittle bit more. ;) This would not be a pedal going on my "board" anyways so I don't care if I don't get every feature in there. I already have the design completed and I actually just got the parts I needed to start building mine. I'll post pics when I post the article.

Andrew
Title: Re: New Looper Design
Post by: robbiemcm on June 23, 2006, 10:42:51 AM
Sounds good. Although I must say I'm not looking forward to making my own PCB for it :icon_lol: I've only ever done PCBs for two things, Easy Drive and Obsidian Overdrive. Either way, I can't wait to have a looper to play around with. Make sure you make a link to a new topic if you start one when the project is done as I don't check the rest of the forums much these days.
Title: Re: New Looper Design
Post by: The Tone God on June 23, 2006, 10:55:24 AM
Sounds good. Although I must say I'm not looking forward to making my own PCB for it :icon_lol: I've only ever done PCBs for two things, Easy Drive and Obsidian Overdrive. Either way, I can't wait to have a looper to play around with.

I'm perfing mine. Maybe someone else will make a board as there are already a few that can be used as a base.

Make sure you make a link to a new topic if you start one when the project is done as I don't check the rest of the forums much these days.

Will do. I'm right now in the middle of writing the article.

Andrew
Title: Re: New Looper Design
Post by: nelson on June 23, 2006, 11:47:24 AM
This is one that I will be doing a PCB for.

If we get our resident Vero boarders to help this could be very accessible.

Not having seen the schematic, I am hoping I can fit this in a 125 style enclosure with 9mm PCB mount pots.

The board mounting vertically in the enclosure as opposed to horizontal. Leaving space for 2 footswitches, jacks and battery.
Title: Re: New Looper Design
Post by: ethrbunny on June 23, 2006, 12:11:03 PM
Gah! This is killing me. I have two 2560s waiting for a schem. Id pay for a PCB! Heck. Im about to pay for a commercial looper  :icon_rolleyes: ...
Title: Re: New Looper Design
Post by: Michael Allen on June 24, 2006, 02:15:13 AM
*shakes off the dust* Ahh.... I might have to give this a shot. Havn't made a layout in quite some time.  Actually the Vanishing Point was the last project I even worked on, what, a year and a half ago? Back in the saddle... This looper is gonna be tight!
Title: Re: New Looper Design
Post by: The Tone God on June 30, 2006, 04:46:21 PM
As per request I am posting a link to the thread introducing my looper that I call Payback. Also in that thread is my answer to the challenge mentioned earlier in this thread. :)

http://www.diystompboxes.com/smfforum/index.php?topic=46680

Enjoy.

Andrew
Title: Re: New Looper Design
Post by: Triple Pole on July 07, 2006, 10:39:12 PM
Hi all
Sorry to be an annoyance but has anyone got a layout for the latest version of the Mobius Lite? I'm really interested in building a straight forward, plays-what-you-just-played looper,  If anyone can help me on my way to this goal, that would be fab ;) does anyone have a layout with parts labelled? Is this thing do-able on perf board or am I going to get etching?

One other thing is, Im quite new to the whole DIY stompboxing, Ive done electronics in school beofre so I basically understand schematics and such but Im a little hazy about attaching switches. How do the lugs of the switches correspond to the labels ABC 123 etc on the the schem?

Thanks
You guys are soooo much smarter than me! lol!
Title: Re: New Looper Design
Post by: RaceDriver205 on July 08, 2006, 01:11:54 AM
Welcome to the site.
You can find the 'mobius trip looper' at www.generalguitargadjets.com (http://www.generalguitargadjets.com), it uses a ISD1xxx (1000 and something), which is available from www.smallbear.com (http://www.smallbear.com). Not as good as 'the tone god's new design, but it is indeed simple. I believe it records a loop of up to 20seconds.
Title: Re: New Looper Design
Post by: Triple Pole on July 08, 2006, 12:48:59 PM
Thanks for the link, that does look simple indeed. I think ill do that :D

Do you know if there are any fixes so that It will use a newer chip with better record times? For two reasons, I dont think ill be able to get that NOS chip in the UK, and also I dont think 20 seconds is enough for say a 12 bar blues progression.

Thanks again
Title: Re: New Looper Design
Post by: nelson on July 08, 2006, 12:52:09 PM
Thanks for the link, that does look simple indeed. I think ill do that :D

Do you know if there are any fixes so that It will use a newer chip with better record times? For two reasons, I dont think ill be able to get that NOS chip in the UK, and also I dont think 20 seconds is enough for say a 12 bar blues progression.

Thanks again


http://www.geocities.com/thetonegod/payback/payback.html


you can get the chips in the UK or they are exceptionally cheap at www.futurlec.com
Title: Re: Lazarus Indeed!
Post by: Triple Pole on July 08, 2006, 01:01:28 PM
Hey guys, talk about bringing threads back from the dead!
I've been spurned into action today by the recent 4x15s looper project which was just posted. I've now got what I consider to be the definitive Lazarus Looper project ready to go, though I'd appreciate it getting the once over by those in the know (Slacker, i'm talking to you!).
The layout now includes the Schmitt switching system designed by slacker, as well as the LFO vibrato system i'd devised (read, copied from Tim's PWM design ;) Thanks Tim ). I decided not to use the buffered effects loop, as it was taking up too much space for how useful it was. I figure anyone building this will have the skills to make an input/output buffer on a bit of perf or something. I think a round of applause is well deserved for the switching scheme, which is very elegantly done. I'm sure I would have come up with something far more complicated and less good. Big thanks also to Bill Bergman for the nice analogue design.

Anyway, as ever thoughts and opinions welcomed.

Oh, and the PCB artwork should print out at 4.4x2.7" @ 300dpi. (It's reversed ready for PnP).

(http://f5.putfile.com/5/13708465893-thumb.gif) (http://putfile.com/pic.php?pic=5/13708465893.gif&s=f5)

(http://f5.putfile.com/5/13708463088-thumb.jpg) (http://putfile.com/pic.php?pic=5/13708463088.jpg&s=f5)

Looking back in the thread ive spotted this. Is this a working layout? This has no vibe or anything right? If this is working, I could make this right?
Title: Re: New Looper Design
Post by: piggyfinger on September 18, 2006, 11:41:05 PM
hey guys, sorry to dig up an old post...
fantastic work on this looper!   i love the sound of the 'lo-fi junky', which i think this would be similar to.
but for MY tastes... a looper isn't really a looper unless you can overdub.
i know this chip can't do overdubbing, but i was wondering if it would be possible with two chips?

now i'm a total noob, and i'm sure this might have alot of problems associated with it...
but here's how i see it:

you have two isd1xxx chips: A and B

1. initial loop gets recorded in chip A, playback starts from chip A after memory is exhausted or person ends loop.
2. Overdub mode would consist of chip A's playback mixed with the live signal, and recorded in chip B.
3. The next overdub layer would be chip B's playback mixed with the live signal and recorded in chip A, and so on.

this would even allow for one level of "Undo" since you could toggle back to the previous chip if needed.
of course the sound is gonna get really muddy really fast, do to making so many analog copies... but it might be cool.

just curious to see what y'all thought of this... again great work on this one!



Title: Re: New Looper Design
Post by: The Tone God on September 18, 2006, 11:50:07 PM
hey guys, sorry to dig up an old post...
fantastic work on this looper!   i love the sound of the 'lo-fi junky', which i think this would be similar to.
but for MY tastes... a looper isn't really a looper unless you can overdub.
i know this chip can't do overdubbing, but i was wondering if it would be possible with two chips?

This is really a topic that could be a thread unto itself. To answer yes I have done an overdubbing looper using a pair ICs. I could see it being done with logic ICs but that would take alot of work.

Andrew
Title: Re: New Looper Design
Post by: abakuzam on April 26, 2012, 11:49:58 AM
Yeah, you can use the play pot for a master volume control, but you might find that the signal coming out of your effects varies in strength, so I added the option of decreasing the gain somewhat at both the send and return. That way i've covered all the bases so to speak.
Usually with volume controls, you want the cap on the wiper, that is going back into the circuit. That will protect the output from any scratchy DC which might be getting onto the pot. I'm not sure how much difference it makes putting it before the pot, but that's the way I try to do things.

Anyway, here are the layouts and PCB's for both versions of my Looper. The schem is also shown, which is the same for both versions, except for the effects loop.
I'm going to say they're complete for now, unless anybody spots any errors, I'd appreciate them being checked.

MOBIUS LITE:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUbuBeDG6woyy28s72eaAkv03ox7LQiBcZin2ameLwc9OaT6Hmzfj8k4x1kagbjASKVOPWvtOU2U36JaHTmX0fL01NXOxtOa5k4DzAyRtLp4A)

MOBIUS LITE PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX6SESjwA3D6y3KDVajujt1-ByxgdAJgp3o9rO1COnKa_vFXW5O7HjLINoT85d4dj9254-WlbJZlTrCXFfxWwwYEIEB6yQikj68ZD4bXxO0Lg)

LAZARUS LAYOUT:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZXTlkRdJ1qAdlJWR3B8RTaac0-_zUDgWOvqyXDbLbAIVDkiLEZxUIfUZEjOW6l6p9T4yD3sG6SF8LWAZxqPVM9hg4ZlvABXe3c_Bp0FAOMl5A)

LAZARUS PCB:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZWygAHRdVj0H5L13zhKJqOlJChC9Wm81_TLohGVH67dqI3YAuGta2NU_UFWyArz4dszI2yzoRqoIANR7BYwvoJn3IUvvqwg9YvQT1VBtekbfQ)

LAZARUS SCHEMATIC:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZX-FyY-eqTRb7DdyPRTeHJOd_oIcHD0MUXwsPPBtmjOAOaGjZDdjsEVSzi83COUOIofbzx3M78SqglQsIrSsiyR9pLmRmt_Zxd0nINEOV-S6g)

DIGITAL SCHEM:
(http://storage.msn.com/x1p3q6ujd6xcOpOfW-G0f53Of6axOUXKnK79AStM-yR3ZUi0LdR40KIp33N79tFg7z3nYyhO_H-8NXwAPx4rrAhc6MzNaYWsILFW6DW8KFuBeEG5HQCd9PLlkkKjadC4nzHeWCp4exBGmLe0TvlZ2jLKA)

is this verified? i want to buil this very much!
Title: Re: New Looper Design
Post by: Jaicen_solo on April 26, 2012, 05:28:56 PM
The design is unverified. I haven't looked at it for a long time, though I think it should work.
To be honest, you're probably better off building the Tonegods payback. I built one on vero, and it worked quite well, though i'm still having a couple of switching issues leaking some digital noise. Probably my vero layout.
Title: Re: New Looper Design
Post by: abakuzam on April 28, 2012, 02:49:34 PM
The design is unverified. I haven't looked at it for a long time, though I think it should work.
To be honest, you're probably better off building the Tonegods payback. I built one on vero, and it worked quite well, though i'm still having a couple of switching issues leaking some digital noise. Probably my vero layout.

thanks for information.But i have a question about tonegod's payback v1; how can i disable the multiple recordinf , i want to record 60 sec only  . is it  possbile?