DIYstompboxes.com

Hello all

My attempts at searching are coming up empty, but I seem to recall reading a thread awhile back in which RG had detailed such a thing - Maybe I am imagining it or am just confused.

Anyway, the story is this: I would like to place an onboard buffer into my bass. But there is just no way I can fit a 9v battery into the tiny control cavity (additional routing is off the table). And I have considered building a coin cell stack-type holder device, but don't really like the idea of having to unscrew the cavity cover repeatedly to change batteries anyway (even if it is only every 6 months).

So - in a perfect world I would like to use a TRS cable to power the buffer from an external Hammond style enclosure. I use a Boss pedal board, so have (relatively clean) 9v on hand already. I was thinking it would be nice to bump this up to 12v or even 18v, and then send it through the cable to power the buffer circuit inside the instrument's control cavity. Instrument cable goes into box R, output cable goes to rest of board from box L. Simple and clean (though not necessarily easy).

I am all ears for any suggestions here - cable type, caveats, warnings; anything. I am relatively decided on taking this path forward, but am still open to valid persuasions against it.

As to the insides of the potential Hammond box, I would like to either assemble/populate an existing RTS PCB, or find a design that works well on a perma/proto type board; I would rather not 'dead bug' something inside the enclosure. I am solid with an iron and with following instructions, but am a little (a lot) lacking in the ability to read and decipher true schematics.


Thank you all in advance! Your time is appreciated

Welcome to the forum. I think the thing you are looking for is this

http://www.till.com/articles/PreampCable/ (http://www.till.com/articles/PreampCable/)

What problems are you experiencing that the buffer will help with?
Have you tried a normal buffer, in a box on the floor...wait you have a boss pedal board? You mean Boss pedals that have buffers already?

Phantom power does not require a third conductor, just blocking cap.

Since you are buffering (no gain) a passive signal, 12-18v headroom seems unimportant. And charge pumps can be noisy.

Yes, I have seen that article. Thank you. But no, I was thinking of sticking an actual buffer circuit inside the instrument itself, not inside the cable housing. But I guess the power box would be the same. But as I said above, going from schematic to solderable protoboard is beyond me (don't laugh!)

And by a Boss pedal board I mean a BCB-60 board; a molded gun-case looking job with an integrated wall wart supply powering 7 power plugs / pedals. To that end, the first pedal inside the case is true bypass (as they all are, until the last pedal. A Boss Giga Delay; so output buffering is already covered).

Fair point on the headroom- so maybe 9v from the box would do just fine. And I could do without any additional noise.

The buffer would be nice to preserve some high end on a rather dark bass, but also to heighten a bit of 'punch' in certain situations. I would be installing a bypass switch to keep the original tone an option when desired. Additionally, my new home has a fair bit of EMI interference that I can't seem to shake in its entirety. Shielding will happen soon (over the weekend likely), but I was under the impression (perhaps mistakenly) that a buffer before any cable run would help to shed a little bit more of that noise (and yes, the instrument is grounded properly, yes the amp is as well, yes it has two HB pickups, yes the dimmer switches are being replaced, so on and so forth).

And I also like the sound of active basses I hear on recordings when played solo - I just have no desire for any gain. So a switchable buffer seems like the best of both worlds, no?

Maybe I'm wrong though...

How small do you need it? There are Vero layouts that are pretty small....
https://tagboardeffects.blogspot.com/2014/08/buffers.html (https://tagboardeffects.blogspot.com/2014/08/buffers.html)

The 8x7 is about 1/2"x 3/4."

A smaller ready made one is from amz
http://www.muzique.com/schem/buffmod1.htm (http://www.muzique.com/schem/buffmod1.htm)

plenty of ways to go at it.

I would build or buy one and try it to see if it makes a difference before getting fancy. Like on of those old Dan Armstrong things that plug right into the guitar...or EHX LPB-1...or a clip on the strap, not pretty, but to experiment.

There won't be any circuitry in the box on the floor will there? just a power jack, mono out jack and TRS to the instrument. But bypass, that would be a switch on the bass?

I have the above mentioned "preamp cable" preamp built into my guitar. but I power it with an onboard 9V battery. Draws very little current - I think I have never changed the battery.
Using a mic cable and TRS jack has it's drawbacks - if your cable breaks - you can't just grab any spare one - you need a TRS one which are not that common. Just a point to think about.

Thanks, IDY.

But I have the buffer part squared away. The PCB or layout I am looking for would be for the phantom box 'guts' only.

Hi & Welcome.. :icon_wink:

So, you  need a simple buffer PCB or layout for +48V power, or what..??

Hey Antonis-

Yeah pretty much. I think 9v will be plenty though, no need for true 48v phantom.

Basically I am looking for advice on how to safely and quietly take a standard 9v pedal wart and plug it into an enclosure that would send the 9v up into the instrument Jack.

Maybe some supply filtering on the 9v jack, and maybe an on / off toggle on the top for when plugging in or removing it the cable. But that is all- just a feeder box.

Oh and yes to IDY- the buffer on / off switch would be on the instrument. If there was one on the box it would only be used to cut power to avoid shorting something as the cable was inserted.

Thank you all for your replies

So perhaps using the term 'Phantom' is making this request confusing. I am only looking for a box to deliver 9v remotely to an instrument from the floor. I have drawn up a little sketch of what I mean below (and included a blank version if anyone feels inclined to draw on it).

The area marked PCB is where I would like to filter the supply. That is what I really need the most help with. Any beyond that, if someone can just look at the layout and say if this is a safe way to do this.

Thanks!


(https://i.postimg.cc/n9vjRXzj/POWER-BOX.png) (https://postimg.cc/n9vjRXzj)

(https://i.postimg.cc/yJkJqQxz/BLANK-BOX.png) (https://postimg.cc/yJkJqQxz)

(https://i.imgur.com/ge3f9mO.png)

R value depends on buffer current and affortable voltage drop..
C value comes out of formulae: C = 0.16 / (f x R), where f << 100/120 Hz (rectified mains frequency)..
CLR value comes out of: (9 - V_LED) / I_LED

Practical values are: R = 10R - 47R, C = 100μF - 470μF and CLR = 2k7 - 10k

Hey Antonis-

Awesome! Many many thanks for this. I can't be the only one interested in making one of these, so hopefully other novices who fear frying their pickups (or burning down their house!) will see this and benefit from the knowledge posted. I actually have one of these trinkets (https://shop.pedalparts.co.uk/product/humstop (https://shop.pedalparts.co.uk/product/humstop)) laying around from a fuzz project, and see that the basic format of what you posted is about the same. I didn't realize that power filtering could be as simple as it appears to be. I thought it would involve many more components.

QUESTIONS:

A) I would like to include an input polarity protection diode to my box as well - I can just lay that across the +/- wires leaving the DC jack before they hit the rest of the PCB, right?
B) Don't I need some sort of diode (or a fuse even?) on the hot wire leaving the switch before it gets to the 'TO INSTRUMENT' jack? Maybe I am just overthinking this.
C) I was thinking of using a 3 pin XLR jack on the power box, and using an XLR to 1/4" cable to the instrument. Is this a bad idea for any reason I am not thinking of (other than a weird cable)?

Anyway, thanks again, man. I really appreciate your insight

A) Yes, as far as diode Cathode (strip band) faces to (+)..
(shunt reverse polarity protection)

B) IMHO, No..

C) A stereo jack (and stereo plug) should also be fine..

Hey Antonis-

That is great. Thanks for your time.

A PCB with all the in / outputs / ground plane accounted for hanging from the switch would be perfect for this, but designing all of that is way over my head. I will work up a design for a permaproto board (I really like these in various sizes for development: https://www.adafruit.com/product/589 (https://www.adafruit.com/product/589)) and check back once again before I solder it all up to make sure I haven't overlooked something...


Thank you again for your help

Quote from: Big Fat Walrus on April 03, 2022, 08:02:41 PM
designing all of that is way over my head.

Just 4 items on 8 X 5 hole board..

(https://i.imgur.com/FIjvDMb.png)


(https://i.imgur.com/S6nhA1X.png)

P.S.
If there isn't 270μF cap handy, go to 220μF or 330μF(preferable)..

Hey Antonis-

Wow; thanks! I just sat down to plot all of this out. But I am glad I checked here first.

By the way, those graphics are great. Did you make all those images yourself and move them into place? Very nice.

Since you have been so helpful, let me pick your brain just a bit more if you will indulge me...

QUESTIONS:

A) The capacitor should be electrolytic, correct? (legs aligned appropriately)
B) Your layout has only one capacitor, and a 10R - 47R range for the resistor (not the CLR). Why does the fuzzdog 'drop in' PCB have two capacitors (C1 = 100u and C2 = 47n) and a 100k resistor? Is this overkill, poor design, or what? (I have attached a picture below). Just trying to wrap my head around the theory here and learn more about the underlying concepts at work.

Again, thank you very much for looking all of this over. This forum is great!


(https://i.postimg.cc/hhqt3FCR/HUM-STOP.png) (https://postimg.cc/hhqt3FCR)

Quote from: Big Fat Walrus on April 04, 2022, 07:17:06 PM
Why does the fuzzdog 'drop in' PCB have two capacitors

Due to their construction, electrolytic capacitors have high parasitic inductance, meaning they stop being capacitors at higher frequencies. A smaller cap (with lower ESL) is often used to compensate for this. https://circuitdigest.com/tutorial/understanding-esr-and-esl-in-capacitors
Probably not important for the task at hand.

Quoteand a 100k resistor?

No no no! The document says "100R minimum 1/2W rated". 100R is 100 Ohms, 100K is 100000 Ohms. It forms an RC low-pass filter (https://en.wikipedia.org/wiki/Low-pass_filter#RC_filter) with the capacitor(s).

Quote from: Big Fat Walrus on April 04, 2022, 07:17:06 PM
By the way, those graphics are great. Did you make all those images yourself and move them into place?

https://bancika.github.io/diy-layout-creator/ (https://bancika.github.io/diy-layout-creator/)

P.S.
Adding C2 (10nF - 100nF) should do no harm..
My only objection concerning Humstop C2 is the type of capacitor.. - IMHO, it should be a ceramic one( for the purpose it's placed there..)

Ha-

Yes, I know K means 1000 - that was simply a typo. I was only wondering why the values differed.

But I guess I never thought about the RC filter part (duh). I never thought about filtering like it was adding a 'tone knob' to the DC jack shunting electrical junk to ground. Very helpful.


Thanks!

Quote from: Big Fat Walrus on April 05, 2022, 05:56:28 AM
But I guess I never thought about the RC filter part (duh). I never thought about filtering like it was adding a 'tone knob' to the DC jack shunting electrical junk to ground.

There isn't any "tone" knob simply because "tone" pertains to frequency, hence concerns AC only.. :icon_wink:
(Frequency of DC is, or should be, 0 Hz - a parallel to X axis flat line..)

What you want to filter here is DC "ripple", which is a result of  - possibly - inadequate smoothing right after AC rectification..
https://www.electronics-tutorials.ws/diode/diode_6.html (https://www.electronics-tutorials.ws/diode/diode_6.html)

P.S.
Hum stopper/eliminator is a bit more complicated case and has to do with ground loops also..

Yeah, the 'tone knob' analogy isn't an entirely accurate one - but something clicked when fiveseven mentioned the filter and it started to help me get my head around the concept.

Thanks for the links, I will definitely check those out. Half the fun of a hobby like this is (to me) the making, but the learning is the other half.

Thanks for helping me get further down the path...  :icon_wink:

Quote from: antonis on April 05, 2022, 05:29:17 AM

Quote from: Big Fat Walrus on April 04, 2022, 07:17:06 PM
By the way, those graphics are great. Did you make all those images yourself and move them into place?

https://bancika.github.io/diy-layout-creator/ (https://bancika.github.io/diy-layout-creator/)

DIYLC is so cool it has its own lengthy thread (https://www.diystompboxes.com/smfforum/index.php?topic=44838.0) right here at DIYSB.

Hello again all-

So I have decided to make the power box 12v (or even 18v) instead of 9v. I would like to make sure I can deliver the buffer at least 9+ volts even after the drop from filtering (but less than 24v). What would be the optimal component values you guys recommend? I tried to calculate this myself, but would like some validation (or correction) on my math - which is probably wrong.

And if I were to add the 47n C2 (ceramic) to the schematic, I would just lay it across the + and - lines just like antonis' diagram (but after the existing 270uf), correct?

And lastly, I really would like to have a pcb made for this that hangs off of the switch. While I do have access to Eagle, I have no idea where to begin designing something like this for production. Is there a service anyone can recommend (or anyone here who does this sort of thing for freelance?) where I provide a layout or schematic and the service will turn that into a Gerber file, etc., for me?

Thanks again for all of your input!

Quote from: Big Fat Walrus on April 17, 2022, 05:34:39 PM
if I were to add the 47n C2 (ceramic) to the schematic, I would just lay it across the + and - lines just like antonis' diagram (but after the existing 270uf), correct?

There is no "before" or "after" for 2 elements placed in parallel.. :icon_wink:
(but place 47nF "after" 270μF if it makes you feel comfortable..)

P.S.
In case of difficulty getting 270μF cap, proceed to 220μF one..

You might want to look at
http://www.geofex.com/FX_images/Onboard_Preamp.pdf
which was designed specifically for some of the issues brought up here. It works on two coin cells, and was designed for low current use, smaller than nearly all opamps. There are coin cell sockets that will let you push cells through an exposed slot in a pickguard.
I did the prototype with through hole components, but an SMD version could probably be mounted to one side of the coin cell holder under the pickguard. No routing of the body.

Quote from: antonis on April 18, 2022, 04:50:36 AM
There is no "before" or "after" for 2 elements placed in parallel.. :icon_wink:
(but place 47nF "after" 270μF if it makes you feel comfortable..)

Thanks for the reminder, antonis. I guess I'll live dangerously then; if I do include it I shall place it before! :icon_wink:

So am I wrong to think that for a 12v (or even 18v) box, some of these values should be changed? Say, for R= 100, C1= 400u, C2= 65n (again, my math is probably wrong)? The buffer current is approximately 3mA.

Quote from: R.G. on April 18, 2022, 04:23:32 PM
You might want to look at
http://www.geofex.com/FX_images/Onboard_Preamp.pdf ...

Thanks, RG. Actually that was my original plan. But the more measurements I took, the worse things looked. This bass has very little room left inside a very shallow rear cavity route (and no routing under the pickguard). Plus I simply cannot bring a schematic to PCB- way above my skill set. So I went with a jack-mounted option. But I am glad you posted that article here. Should anyone who has more space in their cavity and more skills come across this thread with similar questions, they should certainly go down that route.

Q: Is there such a PCB design service where you can send out a layout or schematic and receive a printable file in return? Something ready to send to, say, OSH Park? As much as I would like to learn PCB design, it is thousands of hobby hours down the road from now

Thanks!

Quote from: Big Fat Walrus on April 18, 2022, 06:24:48 PM
Is there such a PCB design service where you can send out a layout or schematic and receive a printable file in return?

Peeps on this forum offer it sometimes, maybe for free if it's simple enough. And sure there are professional establishments that could also help you out with fabrication and assembly but it will cost a lot.
Anyway, for 3 components you really don't need a PCB, you can solder them directly to the jacks. Or if you're thinking about the buffer try asking the guys in this thread: https://www.diystompboxes.com/smfforum/index.php?topic=110259.0

Quoteam I wrong to think that for a 12v (or even 18v) box, some of these values should be changed?

Yes, that's wrong. Same values, just make sure the caps have the proper voltage rating (e.g. 25 V for 18 V supply).

Quote from: FiveseveN on April 19, 2022, 01:59:36 AM
Yes, that's wrong. Same values, just make sure the caps have the proper voltage rating (e.g. 25 V for 18 V supply).

Hmm. Well, I thought my math was wrong so no surprise there. I guess that makes things easier.

Quote from: FiveseveN on April 19, 2022, 01:59:36 AM
Anyway, for 3 components you really don't need a PCB, you can solder them directly to the jacks...

Yeah, I know. I just wanted the sturdiness of something hanging off the foot switch. I have looked, but can't seem to find any proto board with hole spacing that will fit a DP or 3PDT. Maybe I'll just keeping digging for something on that end.

Thanks!

Quote from: Big Fat Walrus on April 18, 2022, 06:24:48 PM
So am I wrong to think that for a 12v (or even 18v) box, some of these values should be changed? Say, for R= 100, C1= 400u, C2= 65n (again, my math is probably wrong)? The buffer current is approximately 3mA.

As 57 already answered, LPF items values only depend on cut-off frequency of interest, which is 0.159/(R x C)..
but..
Cap(s) voltage rating depends on working voltage (the one across its legs) and Resistor value concerns affortable voltage drop across it (caused by supply current.. - 3mA in your case..)
Also, R power rating depends on its actuall value and supply current (I² x R) but this shouldn't bother us here 'cause it's slightly lower than 1mW :icon_wink:

You can realize that R value should be a compromise between voltage drop from power supply to buffer and respective cap value in the mean of undersizing R value (for less voltage drop) results into oversizing C value (to maintain constant R x C product..)
But caps value (not voltage rating) is both cost and space related where resistor value (not power rating) is irrelevant both to cost and space..

Hey antonis!

Sorry, I just saw your reply now. Thank you, that is very informative. And also thanks to 5 7 for your explanation. Maybe this is also a good time to learn Eagle with a seemingly simple first project...

I recently stumbled across this link (http://www.muzique.com/news/dc-power-filter-box/ (http://www.muzique.com/news/dc-power-filter-box/)) to an interesting AMZ widget. Am I crazy for thinking that this would be a nice addition to an external power box like we are discussing? Or am I just overthinking this?

It seems like there is no down side to making sure A) the power ripple is minimized and B) the power has been 'cleaned up' the best it can be - especially if I start with a voltage that allows sufficient drop (12v would allow 3v loss, etc). Is this correct?

Basically, this house is pretty electrically noisy and I would like to keep as much 'junk' as possible from making its way into the audio path. And I suppose overkill is acceptable in a situation like this?

I've just realize that you didn't say the way for 3V drop..!! :icon_wink:
(which drop, by the way,  is fine for a voltage regulator ...)

OK, maybe poor explanation on my part

What I mean to say is: As long as I can get above 9v out of this box into the TRS jack, everything is good. So even if my over the top desire to filter and clean the power supply (wall wart) cost a few V along the way, that is OK...

If so, then overkill is more than welcome.. :icon_wink:

For 3mA current draw, a resistor of 470R and a capacitor of 100μF (3.4Hz cut-off frequecy) shoud be fine..

Of course, if you consider yourself serious overkiller, implement Jack's LC T-bridge filter with a resistor (100R - 470R) in series with input inductor..
Cap will serve both for ripple reduction (with R) and for RF & clock noise (with Ls)..

P.S.
Under your own risk, of course..!! :icon_lol:

Nice.

I assume the 'risk' comment is sarcastic though. Like I said earlier, my knowledge of these things is 'just enough to be dangerous.' So I would like to avoid any risks  :icon_wink:

But thank you for all of your advice - I believe I have almost bothered you enough here. I will now attempt to draw up a schematic (first time, so will need someone to double check it) so that I can attempt to make this into a PCB in Eagle. If it all works I'll post the Gerber here for all to use as this forum has been so helpful.

Thanks!

So I am beginning to use a schematic layout program. Baby steps, but I guess you've got to start somewhere.

Before I get too far along here, does this look like what you are suggesting? (obviously the switch and the LED/CLR, jacks, etc are omitted)


(https://i.postimg.cc/tZdNY611/circuit-2.png) (https://postimg.cc/tZdNY611)

For 3mA load current, you'll have 1.4V drop across 470Ω resistor so about 7.6V availiable for your load..
If it isn't OK, reduce R1 value down to 100Ω  - RC  LPF new corner frequency at 3.4Hz should also be fine..)

P.S.1
I should ommit inductor or place it after 470μF cap or increace significantly its value..!!
(as it is it raises cut-off frequency at about 404Hz..)

http://sim.okawa-denshi.jp/en/RLCtool.php (http://sim.okawa-denshi.jp/en/RLCtool.php)

P.S.2
Value of 330 μH taken from Jack's filter: http://www.muzique.com/news/dc-power-filter-box/ (http://www.muzique.com/news/dc-power-filter-box/) refers on LC T-bridge LPF..
(it has different cut-off calculation formula..)

Could you plz post a schematic of circuit of interest and power supply intended use..??

It should be more easy for us to suggest you the power supply filter.. :icon_wink:

Hey Antonis,

I don't have a diagram of the buffer circuit I'll be using inside the guitar, as I purchased it from a company. But it can run on 9 - 24v and draws 3mA.

I was trying to draw a schematic for the external box to power it over TRS cable based on your suggestions earlier in the thread, and Jack's filter box. Obviously, I have never designed a circuit before (or even drawn a schematic), but I thought this would be a good place to start. And then hopefully I could create a PCB for it as well. An easier project to start on vs., say, a delay pedal.

I didn't know this (https://www.emgpickups.com/parts/es-918.html (https://www.emgpickups.com/parts/es-918.html)) even existed a few weeks ago - I got the idea from an older Alembic someone I know has. But I would rather build one myself, and that EMG seems like a lot of money for a few parts that I already have mostly in my cabinet. I just want to take the same principle, but filter the power ripple and hum, and add an LED and an On / Off switch. As long as the box outputs above 9v through the ring terminal...

-Oh- I mislabeled that power rail in the picture. I meant 12v. I thought I could just use a standard wall wart 2.1mm adapter to power the box.


Thanks for your patience!

Quote from: Big Fat Walrus on May 08, 2022, 08:08:17 AM
-Oh- I mislabeled that power rail in the picture. I meant 12v. I thought I could just use a standard wall wart 2.1mm adapter to power the box.

If so, retaing R1 value, get rid of inductor and place another cap (1nf or so) in parallel with existing ones...
(you'll be proud for your super-fancy-quiet filter..) :icon_wink:

OK, so this will take care of all the filtering? I'll just need to use the switch and led to the schematic?


(https://i.postimg.cc/XZFQ4D93/circuit-3.png) (https://postimg.cc/XZFQ4D93)

Quote from: Big Fat Walrus on May 08, 2022, 10:28:50 AM
OK, so this will take care of all the filtering?

Have you the contract to be signed prepared..?? :icon_smile:

Quote from: Big Fat Walrus on May 08, 2022, 10:28:50 AM
I'll just need to use the switch and led to the schematic?
(https://i.postimg.cc/XZFQ4D93/circuit-3.png) (https://postimg.cc/XZFQ4D93)

Yeappp.. :icon_wink:

Quote from: antonis on May 08, 2022, 02:06:05 PM
Have you the contract to be signed prepared..?? :icon_smile:

Ha ha, that's up to you my friend. I believe you have earned some compensation for all your help here.  :icon_idea: Perhaps we should name the circuit after you?

Now I just need to sludge through the Eagle part of this. Once I have something that seems good I'll ask for someone on the board's help to double check it all, and then have a few printed. And as promised, I will post all the files so anyone can produce it if needed. Share and share alike, no?

Thanks!

So I have attached my schematic below.

The only question I have left is how to calculate what the voltage out will be. I know the R values can change that, but (as a novice) I am having a hard time with this because it is connected to another circuit. 12V goes in, and hopefully 10 or so comes out, but I can't seem to actually calculate this.

And also- C1 is obviously an Elec cap. But what type should the other two be. Both ceramic? One ceramic and one film?

(https://i.postimg.cc/rdhmNZtH/POWER-CIRCUIT.png) (https://postimg.cc/rdhmNZtH)

R1 + LED should be connected to +12V before R2.. :icon_wink:

For Vout (actually Vin - R2 voltage drop) implement Ohm's Law..
V = I x R, where V is the voltage drop across R and I is the current flowing through R.. :icon_wink:

If I recall it right, your circuit has 3mA (0.003A) current need..
So, voltage drop across 470 Ohms simply is 1.41V..
12V -1.41V = 10.59V = Vout.. :icon_wink:

P.S.
Make C3 1nF (in case of μ isn't a typo..)
Both C2 & C3 can be either film or ceramic..
(the later suggested..)

Yes, that is a typo. It is in fact 1nf. Should C2 and C3 both be ceramic? Or only C2?

And- what if I left R1 after the switch? Still works, right? I wanted to be able to use a SPDT to switch it all

Make both C2 and C3 ceramic and walk in peace.. :icon_wink:

If you place R1 + LED after R1, you'll have to add LED's current on 3mA to calculate total voltage drop across R1..
('cause both circuit and LED current pass through R1)

OK great; thank you.

So, that means the voltage drop across R2 should be adjusted to 23mA (for a red LED)? And keeping the 4k7 value for R1, that means that Vout= 1.19v?

Boo.

Wait a minute-

I admit that this might be a stupid question, but I come here to learn. So here we go-

I don't understand why it matters where R1 and LED are placed. They are still connected to the same 12v IN source, and will still drop the V OUT voltage the same no matter where they are placed. Right?

The switch is used to turn the power on or off to the jack (OUT+ solder pad). The LED is there to indicate when power is going to the + V OUT pad, NOT to indicate when the circuit has 12v IN connected. So isn't it the same regardless of whether it is placed before or after R2?

All this circuit needs to do is provide more than 9v to the V OUT pad (but ideally more than that) after filtering the ripple, hum, etc.

Am I missing something?

Thanks!

Well, the "on" LED seems to be the right side to me (has to be after the "on" switch). However, if you use a high efficiency LED, you might use as high as 10k instead of 4k7 & still get good light from it and less loading on the output voltage.

I see you put a reverse polarity protection diode on the input - so do you expect reverse power as a possibility? If so, a power supply capable of over 1A can either blow the diode open circuit or cause it to short circuit. Open circuit won't do as the reverse power can continue to the rest of circuit. If you place the diode after the 470R filter resistor, the resistor will either limit the reverse supply current or get hot/smoke and die. Not necessarily a bad outcome if it protects against further damage and a damaged resistor usually just cuts the feed like a fuse.

Case closed..
(I hope so..) :icon_wink:

(https://i.imgur.com/Sck2Enu.png)

P.S.
> If you place the diode after the 470R filter resistor, the resistor will either limit the reverse supply current or get hot/smoke and die.<

Jim, in the former case any circuit semiconductor will suffer from reverse voltage where in the later case nobody can guarantee ultra-fast resistor death..

links
https://web.archive.org/web/20100824183740if_/http://www.ebs.bass.se/2009/manuals/NeoGorm.pdf (https://web.archive.org/web/20100824183740if_/http://www.ebs.bass.se/2009/manuals/NeoGorm.pdf)

links in the thread below don't work but it should help
https://www.diystompboxes.com/smfforum/index.php?topic=73492.msg596553#msg596553 (https://www.diystompboxes.com/smfforum/index.php?topic=73492.msg596553#msg596553)

IIRC SD or another(s) pickup company had wiring diagram for active circuits powered via a circuit like in the EBS link

Let's make it more graspable.. :icon_wink:

(https://i.imgur.com/ZJQNmkf.png)

Thanks, guys

Quote from: anotherjim on May 15, 2022, 06:11:32 AM
I see you put a reverse polarity protection diode on the input - so do you expect reverse power as a possibility?

Not really, I just thought it would be safer than not having anything at all there

Quote from: antonis on May 15, 2022, 07:38:23 AM
Case closed..
(I hope so..) :icon_wink:

Hmm. This is a dilemma

Quote from: antonis on May 15, 2022, 08:14:11 AM
Let's make it more graspable.. :icon_wink:

Yes, thank you. I need crayons at this point ha ha

You know what, I think I am wasting everyone's time here. So I will buy a book on electronics and try to learn some of these principles on my own. Building pedal kits is basically 'paint by numbers,' and gives you (me) the idea that you understand more than you really do.

Anyway, as promised I have a G*rb*r file for this board that I will send to anyone who wants it. Just send a PM. A small thank you for all the help I have received here. As antonis points out the R values might need to be tweaked to get the desired output, but as Jim points out different LEDs might help with that. As anyone who has read through this thread knows, that is above my level of understanding. But I digress...


(https://i.postimg.cc/CRchgJVY/PCB.png) (https://postimg.cc/CRchgJVY)

Here is an image of the board. It is 1.44" (36.58mm) wide by 2.17" (55.12mm) tall. It is arranged so that it can hang from a solder lug 3PDT switch inside an enclosure, but a SPDT toggle switch in the center column will work as well. The status LED is located just above the switch. The input and outputs are all solder pads, so you can use the jacks that you prefer. There is also an extra GND solder pad on the output side of the board, so a mute switch could be added between the in and out jack if desired. The board drilling will accept 1w resistors and a 50v Electrolytic cap (C1).

So thanks to everyone who has helped along the way, especially antonis. My apologies for bugging everyone!

I shouldn't design boards before electronics book purchase (and studing.. :icon_wink:) or there should be some space/cost waste..
e.g.
Neither resistors need to be 1W nor C1 needs to be rated at 50V..
Caps should be rated at working voltage across their legs (ok.. a bit higher) and resistors at their value times current squared..

Quote from: antonis on May 15, 2022, 01:38:31 PM
I shouldn't design boards before electronics book purchase (and studing.. :icon_wink:) or there should be some space/cost waste..

Yes, that is a fair point. But I have a need for something like this now, and did not like the other options currently available to me.

Quote from: antonis on May 15, 2022, 01:38:31 PM
Neither resistors need to be 1W nor C1 needs to be rated at 50V..

And yes, I know that. But it won't hurt to use larger values, and it is safe. There is plenty of empty space inside my enclosure, so why not? And, in the event that someone else has a similar need but at a higher voltage, this will work for them too right 'out of the box.' Smaller value components can still be used if desired.

Please don't take my previous post as 'I'm taking my ball and leaving.' I did not mean it that way at all. I am very appreciative for all your help and patience, and it led me to the realization that I really should build a better foundation of knowledge before I stray from just building others' circuits. This forum has been very kind and welcoming to me, which is why I wanted to offer the board to anyone who wanted on at no cost. While this circuit might still need a little fine tuning, it is probably still a better and cheaper option for anyone who can solder and drill an enclosure than what is commercially available (say, this: https://www.emgpickups.com/parts/es-918.html (https://www.emgpickups.com/parts/es-918.html))...

But again, sincere thanks to anyone who participated here and helped me learn more about a hobby I really like