Hello everyone
I'm wondering if anyone could help / offer sympathy / prayers for my darkened soul as appropriate. I'm trying to trace my Langtronics Bone Collector so that I can build a new version of it with more controls and the ability to blend dry audio with the circuit (it's a fierce squealy synthy fuzz thing, based on Tim Escobedo's Uglyface schematic, but with a lot more parts). The original pedal was covered in goop (glue gun plastic / hot glue) which I've scraped away mostly and I've tried to trace the circuit and have drawn a schematic below. I've tried to build this on breadboard twice now, first time did nothing, the current version (which had 5 extra parts I forgot in version 1, who would've thought they'd be useful?) passes a mild version of the astonishing noise the original is capable of and the potentiometers in the circuit do nothing (well they must do something, since removing them kills the audio, but turning them has no effect on the sound). I made a couple of substitutes due to lack of parts (the 82pF cap is a 100pF on my breadboard and the 120r resistor is a 150r on my board)
When looking at the photos / my drawings it's highly likely that I've drawn in resistors of the wrong values - one of the many joys of being colour blind is that I've had to take photos of the PCB and then use a colour picker tool in Photoshop to work out what the colours are on the resistor, and it's quite likely that I've got them wrong, which might be the reason the circuit isn't behaving itself. Mr Duck from down under has offered kindly to look at my photos of the resistors but I'm sure he won't mind if anyone else wants to play spot the resistor :)
Here's my schematic and a drawing of the backside of the PCB (components reversed because they are on the other side of the PCB)
(http://i.imgur.com/Fj3ZHRq.png)
Here's a photo with annotations of the topside of the PCB
(http://i.imgur.com/NEHStCM.jpg)
Another photo of two resistors that are hard to see in the above photo
(http://i.imgur.com/qMtMVq9.jpg)
photo of the back of the PCB
(http://i.imgur.com/vZ21UxC.jpg)
trimpot that I'm not sure what value it is
(http://i.imgur.com/sXcrl4E.jpg)
Thanks very much for any help!
clr appears to be 2k2. alll other resistor values appear korreckt. can you hold the board up to a strong light so we can see shadows of copper traces please - there is something screwy with the R8//R11 connections not making itself apparent on the copper.
you could use TL072 as buffer with a little gain, followed by another gain stage feeding a rectifier, or something like that, to replace the lm386.
your meter should expose the trimpot value, and which end is ldr.
Eagle eyes, that's what you've got, not duck eyes :) The backlit photo (not great, I don't think my phone is good for this sort of photography) shows a trace link between R8/R11 and pin 6 of the TL072!!!
(http://i.imgur.com/WhQ5W8E.jpg)
Thanks for identifying the CLR, the goop was making it hard to get some colour values that I could guess correctly.
Regarding the handmade vactrol; how do I determine which end is the LED and which is the LDR? I put my DMM on all the leads with music playing through the pedal and both ends of the tube flicker on and off quickly, while meter readings on all the four legs tend to jump around constantly... I think that the tube is brightest at the end facing the NE555 which implies that in my diagram the vactrol is the wrong way around.
The trimpot does indeed read as 1.2K(checked with the DMM). I'm currently using a 1K pot, presumably that shouldn't have a massive difference of effect?
I'll ask you about the comments on the TL072 later, I'm off to fix the gap between R8 and R11 to see if any magic happens!
OK I now have more volume and distortion :) but no control over it, and bizarrely disconnecting either potentiometer still allows music through the circuit (unless I remove the final pot wiper connector to out of course), so something is shorting the music through ground and into the socket? Who knows... anyway while re arranging the components I have discovered something that almost made me cry... I've swapped the NE555 for the TL072 on the breadboard... two thirds of my connections are therefore probably rubbish and it's a small miracle that anything is actually happening at all :(
I think I will need some sleep before I can begin the miserable process of laying this circuit out again... how did John Cleese so eloquently put it? "It's not the despair, I can take the despair; it's the hope I can't stand"
Edit: if the LED side of the vactrol now goes into pins 6 and 7 of the NE555, which pin takes the positive leg of the LED? Any guesses? I'm guessing at positive leg goes to pin 7 (discharge) and negative leg goes to pin 6 (Threshold). Feel free to tell me I'm wrong.
well your circuit matches the board as you have presented it, but that circuit seems to be using the ldr in a different manner to the uglyface.
[smaller images, maybe? it's better to have the connecting lines on screen instead of whitespace and scroll. and when drawing a box-type thing, like the 555, it is nice to include some hint to the pin functions. tr for trigger, out for output, things like that. same goes for the 386, draw it as a triangle to indicate its function, then add the (+)(-) inputs so's we know what those parts are connecting to. once you indicate the pins by name and number, they can be moved about "the box" to clarify/ease the connections. and the dual opamp is two opamps, not a box.]
It would be logical for the 386 to be driving the vactrol LED. It would make no sense for the 386 pre-amp to be driving the LDR.
Beware some of the "boutique" designs can contain bad practice and superfluous "copy catch" components. The 386 can end up driving the LED directly with no CLR present if the sensitivity pot is max. I don't know if that vactrol contains an integral LED CLR. The 2.2uF cap in between is wrong polarity on the scheme; should be negative to the pot. There appear to be extra 1M and 56k resistors (R8, R11) on the reference voltage divider that can't be doing much of consequence IF they really are placed as drawn.
(http://i.imgur.com/Fj3ZHRq.png)
Quote from: duck_arse on July 10, 2017, 10:55:13 AM
well your circuit matches the board as you have presented it, but that circuit seems to be using the ldr in a different manner to the uglyface.
[smaller images, maybe? it's better to have the connecting lines on screen instead of whitespace and scroll. and when drawing a box-type thing, like the 555, it is nice to include some hint to the pin functions. tr for trigger, out for output, things like that. same goes for the 386, draw it as a triangle to indicate its function, then add the (+)(-) inputs so's we know what those parts are connecting to. once you indicate the pins by name and number, they can be moved about "the box" to clarify/ease the connections. and the dual opamp is two opamps, not a box.]
OK duck, I will try to draw things smaller soon... I go large so that my eyes can actually see what I'm drawing (my eyesight is rather poor, and only one eye can actually focus properly, the other one blurs everything in a mostly horizontal direction :( ) I sense another expensive visit to the opticians soon.
Well I rebuilt the entire circuit tonight, found some extra components that weren't attached, added a few I had missed... but now I have a reasonably pleasant fuzz that sputters a bit as it decays, but it's not that loud (compared to how deafeningly loud the original pedal is) and there's no synth noises. The volume pot (the log 100K one) now makes the circuit a bit louder at one end of the sweep, but not a huge volume jump. The 1K pot makes a lot of weird crackles if you turn it, but it doesn't do much else. Maybe I need to find a 1.2K pot?
I'm wondering about removing the NSL32 I put in and sticking a super bright white LED and an LDR in it's place like the original - perhaps the issue is the NSL32 not being in the same brightness / resistance range as the one on the original pedal. I think the 4K7 (R3) is the CLR for that LED, which means the positive leg of the LED would connect with pin 7 of the NE555 as I've got it. Something to try once I've had some sleep. Thanks for your suggestions, I'll re draw soon.
Hmmm I agree about labelling the ICs, that's a good point. Why are opamps triangles? They look like boxes to me (they even feel like boxes, so I know that's not my eyesight!). Boxes make more sense to me to draw, but I shall bow to your capricious whims and go to sharpen my pencil... OK, push the mouse about. I'll make updates tomorrow, it's too late now and I think I need to sleep without breaking anything new (I managed to break the original pedal this evening; it's full of solid core wire which is really brittle as I've discovered - but at least I soldered it back together again and it still works!)
Quote from: anotherjim on July 10, 2017, 04:22:25 PM
It would be logical for the 386 to be driving the vactrol LED. It would make no sense for the 386 pre-amp to be driving the LDR.
Beware some of the "boutique" designs can contain bad practice and superfluous "copy catch" components. The 386 can end up driving the LED directly with no CLR present if the sensitivity pot is max. I don't know if that vactrol contains an integral LED CLR. The 2.2uF cap in between is wrong polarity on the scheme; should be negative to the pot. There appear to be extra 1M and 56k resistors (R8, R11) on the reference voltage divider that can't be doing much of consequence IF they really are placed as drawn.
Hi anotherjim - thanks very much... sounds like I have the NSL32 in back to front then! I will swap that about tomorrow. I don't know if the vactrol contains a CLR of its own - it's pretty small, but who knows? It's gooped up with hot glue; I had a go at cutting some of it out, but it fills the entire tube of the vactrol and it's not shifting :( Well spotted on the 2.2uF cap, I've swapped that around now. I will double check R8 and R11, but yes they do seem to be where I've drawn them. I don't know enough to tell if that's wrong or not, like you say this might not be the best way to construct the circuit.
when I say blah blah do it like this - just ignore me. develop a circuit drawing style that suits you, makes sense to you, that you can read.
opamp triangles are representative of the IC internals, so you know at a glance you have some amplifiying going on, rather than some boxing going on. and you can say/see inverting, or non-inverting buffering, like that.
use a 1k trimpot, you'll be hard pressed to find a 1k2. you can substitute a pot - 250k + 47k resistor in series - for the ldr to test the function of the 555. and an external led should indicate the 386 functioning. as the output pot dangles from the 555 output pin, making about 7V squarewaves, you should have a lot of volume on tap.
moids! I've done a sloppy redraw from your copper-side, with no values and wrong part numbers. the connections should be correct, but I'm not 100% about the R2//R3 connections (my numbers). schem attached.
(https://s12.postimg.org/84h7fr5jt/moids.bones.png) (https://postimg.org/image/84h7fr5jt/)
anybody looking it over - let me know for corrections and errors, please.
[edit :] why does it have two pulldown resistors, the 1M and the 10M? one of anotherjim's traps?
Wow, thanks Duck! I've actually been re drawing my schematic to make it more 'normal' but got stuck at how to draw the TL072 because I couldn't figure out which triangle got which of pins 4 and 8 - so you don't mention them at all on your schematic, is this because it's obvious to most people that a TL072 has power going to pin 8 and pin 4 goes to ground?
In other news I discovered that I had not connected the 22uF capacitor after the 1n4001 Diode to the vactrol (LED side)... doing that gave me a decent fuzz, quite powerful and (I think) is generating some octave down sound, kind of synthy. However the potentiometers do nothing at all which is weird. I tried swapping the Vactrol out for an LED going to pins 6 and 7 of the NE 555 and a 5K - 500K LDR to connect elsewhere in the circuit. The LED will only very occasionally flicker slightly (I tried white and red LEDs). If I bridge pins 5 and 6 of the NE 555 then the LED glows constantly. Duck, I think you may have copied my mistake from my schematic there - look at the drawing of the back of the PCB and that capacitor connects to the vactrol and not to ground.
No sign of the synth noises of the original pedal, apart from at one point last night when it emitted a furious high pitch that really hurt my ears :)
The original pedal's vactrol only lights up when the guitar is playing - not sure if that's a useful clue or not?
Measuring the NE555 at pin 6 I get 0.7v DC, but if I strum the guitar this jumps to 4v and then decays. Pin 7 is constantly reporting 9.12v.
Maybe the NE555 is busted or suffering from whatever the reason you warned me to avoid using them (at the weekend I'll try to order some new parts and get the better 555 chip I mentioned). I do still need to find a 120ohms resistor and an 82pF capacitor, perhaps the lack of these correct components has an effect.
To me it looks like R3 should have a capacitor after it before it goes to ground - in the drawing I made of the back of the PCB the 56K resistor connects to a 10uF before it goes to ground (or does that not happen?)
Thanks for your help!
today I was farnargling some papers, and the mxr blue box circuit appeared. lo! and behold, guess what the bonecrusher is based on? well, at least the front end, up to the 555. only a few value changes I could see.
but the bonecrunch at hand. the LM386 is used to drive the led with the audio input, so should only light when signal applied. the light is coupled to the ldr in the 555 timing string, so as the led brights, the ldr will lower its resistance, and the timer will - erm, either run faster or decrease its "off" (or on, can't remember) time. a form of envelope control. the tl072 provides a whack load of gain to a comparator wired opamp, which goes on or off at a great rate, feeding the reset pin of the 555. the exact operation of the 555 is currently beyond me, but it will be outputing squarewaves at pin 3, fed to the level pot, complete with the blue box "tone cap", the 10nF.
so, now my dia - I redrew the LM386 for my own porpoises, and left off the power pins. the lm386 power pin connects to the 1N4001 and (my) C12, nothing else I can see connects to that diode. this is strange, but workable, in that it will protect the 386 from reverse polarity supply, but not the rest of the circuit. oh, well.
the TL072 power pins are there, but are not so clearly marked. as for your cap and led connections, you have me confused. it looks to me as tho the led hangs straight from the trimpot, and the trimmer hangs off the 386 via a cap. which seems sane.
you should not be connecting the LED to the 555 at all. what I've shown as IC1B is the comparator, and I had the bluebox circuit on the BB recently - this section was giving me trouble cause it wouldn't stop creating fluff [it's not fuzz, because it is not useful, so "fluff"], I think bonesman might have 'cured' that problem by pulling one leg (-) of the comp high (to V+) via my R2.
any clearer now?
[edit :] while I think of it, the 555 is as near indestructable a chip as you could want. shoving 9V up its jaxy might finish it off, but if you haven't done that, carry on. and in this circuit, as you are taking the output from the 555, the ugly switching spikes they produce (that the cmos version had designed out) probably won't matter.
I drew a new picture :)
(http://i.imgur.com/lrVV9WE.jpg)
And with any luck it's smaller, displays easily here and has the right opamp symbols (I'm learning!). I found your power symbols for the TL072 in the end, but I've attached them to the opamps in my drawing to help me remember where things go.
Now, are you sitting comfortably? Fancy a chuckle? Guess who didn't connect the power and ground of his breadboard from the top half of the board to the bottom half of the breadboard? Guess which part of the circuit was in that lower half? Yes, it was the TL072. @#$% me did I jump when I strummed the guitar having the had the amp volume on about 8 (so I could hear anything coming out of the circuit) and my headphones were plugged in because everyone else is asleep. No, no, I never wanted to hear anything over 3000Hz anyway. I seem to be hearing a strange high pitch drone signal... the aliens, they are signalling to me!
So... the volume pot now works :) I removed the Vactrol because it did bugger all (maybe I killed it earlier? I did shove the damn thing in every possible hole to see if something would happen... hmmm don't try that at home kids!) Anyway, I placed a 5K - 500K LDR on pins 6 and 7 of the NE555. I stuck a White LED with the long leg to the wiper of the 1K pot (sensitivity) and the short leg to ground. I now get some synthy squarewave noises, but the LED will not light up. I've tested it on its own (with a 2.2K resistor) and it lights up beautifully, but not here. As you pointed out the LED will control the synth sound cutting in and out, so at the moment it is just fading in and out with the audio, but on the original pedal it only kicks in when the loudest notes play. Adjusting the Sensitivity pot didn't do much either, I tried a larger pot (2K lin) and that made no difference- the LED refuses to come on. That looks like the last thing to fix - any guesses?
Thanks again :)
LED with a higher forward voltage than the original vactrol will have weaker performance. LDR in the open suffers from ambient light already operating it. In a vactrol, the close coupling between LDR and LED inside the dark case means that useful LED light output can be so slight it's invisible out in the open.
You can test the vactrol same as you tested a LED, only instead of looking for LED light, measure the change in LDR resistance with your DMM when the LED should be lit. Don't forget to use a CLR, 2k2 should be ok.
Looking at NSL32 datasheet shows it does NOT have an integral CLR for the LED, so there has been plenty of opportunity for it to be blown by excessive current. Even connected in the circuit as shown, the 386 is quite capable of delivering damaging current into the LED with only the impedance of that 2.2uF cap to limit it.
if you were wanting a little more maddness, you might try connecting a cap (?100nF? for a start) between the LM386 output pin and the 555 control voltage pin. then your osc rate should warble up or down (I don't know, maybe both, alternately) with input signal level. well, massively distorted by the 386, but still.
diagramming - becomes neater if you take a point, like the junction of R6//R9//10uF and call it V/2, or Vref, or Vcc/2, or bias. then you can use shorthand, like an arrowhead, at each point connected to "bias", and you don't then need lines running full length of the dia. this is how/why we use the ground symbol (and something like V+ arrow), to reduce lines.
See Igor, it moves!
Thanks very much chaps we have a winner :) anotherjim was right, I'd fried my NSL32s. Both of them. Ouch. Plus a couple of red LEDs, but I have plenty of those so not so ouch.
The lack of illumination of the LED was caused by weak connections on the cables I'm using to connect the board and its components together (some dodgy male to female connectors and a strip in the breadboard that doesn't seem to conduct electricity). The circuit needs bright light though. I removed the suggested 2k2 resistor and just took the power from the 2.2uF from pin 5 of the LM386 to make it brighter. Could I run two LEDs this way, for extra brightness? Because when I shine a torch on the LDR (yes I'm doing this in the dark so I can check the LED is working) the synth noise is even greater and wilder! Maybe this should be on a switch to add more squeals?
Duck, that cap idea is quite genius :) 100nF and lower didn't do much (slight high pitch edge), at 1uF things start to get interesting, there's a slight %^&*ed wah edge to the sound, plus increased arpeggiation of the circuit, but with some constant noise on the bridge and neck pickups - switching to the mid pickup removes this. Me being me, I had to go higher! 10uF is really wild, a strong wah effect on the synth sounds, but constant noise on all pickups (maybe this will be better once everything is soldered?) I'll keep it, but if there was a way to tame the noise, then it would be cool to hear it thanks. I think I'll use a DP3T switch for the caps so I can have original (no cap), 1uF and 10uF as options.
Would the synth be wilder If I put a 10uF between pins 1 and 8 of it (the data sheet seems to think the output will become 42dB!) I might have to make that a switched in option as well.
I have changed the sensitivity pot to 2K - the synth sound is larger with this pot than the 1K I was using... I might try 5K tomorrow? Is that likely to nuke the LED? I'm asking because I only have two ultrabright LEDs left (time to buy some more). When the pot is set to off it turns off the synth sounds and seems to make the arpeggiation of the circuit stronger. As I turn it on I get more and more synth sound, although there's not a huge range, so I can see why the original designer made this as a trimpot inside set to maximum (maybe he could've just used a fixed resistor?)
Time to start thinking of mods... I think I won't upset the circuit as it is to make a clean blend, I'll use the Mr Black Tiger Boost schematic and then feed the two signals together with a blend knob.
Thanks again, I'm happy... but need some sleep. Bedtime for me.
Totally changed edit!
Maybe better yet, actually find out what is the smallest CLR for the highest likely voltage in the circuit that could cause a damaging current.
NSL32 max LED current is 40mA. Being a diode, it only reacts to half the voltage swing of the audio signal. As drawn, that is the positive half. The coupling capacitor removes the 386 output 4.5v DC bias meaning the positive swing seen by the LED is 0v to nearly 4.5v. The LED has a Vf of 2v, so only 2.5v needs to be absorbed by the CLR. Ohms law tells you that R=V/I so 2.5/.04 and nearest standard value R for that is 68R.
40mA is a huge current for the job a vactrol LED needs to do, so I say we can raise the 68R somewhat and also protect against the worst fault state it might encounter. I'd say the worst state is a short to the +9v supply. Easily encountered on the breadboard or due to assembly error.
Calculating again for the 9v case with 7v to lose on the CLR is 7/.04 is close to a 180R value.
for moids eyes ONLY - http://i.imgur.com/PyToWOn.png
if you, moids, have a butchers at the circuit linked, find IC4 where it says "CV mod". the mod is next the title box, and shows how to wire an LDR to the CV input via a switch. (let's ignore SW7 for the moment, connect the ldr straight to pin 5.) now when you shine light on that ldr, one position will make faster, the other will make slower. from memory. the lisght can come from a led driven by the lm386, or from ambient with your hand waving, whatever.
run out of ldr's? get those bung nsl's you kilt, and carefully cut-off the led end. should be a semi-light-shielded ldr in there somewhere.
pins 1 and 8 are connected together by a wire. you won't get any more gain by sticking a cap in there instead. it might make it less bass responsive or something. and if you are going higher than the 1k trimpot, make sure you CLR.
I SAID - how are the ears?
Quote from: anotherjim on July 16, 2017, 05:21:56 AM
Totally changed edit!
Maybe better yet, actually find out what is the smallest CLR for the highest likely voltage in the circuit that could cause a damaging current.
NSL32 max LED current is 40mA. Being a diode, it only reacts to half the voltage swing of the audio signal. As drawn, that is the positive half. The coupling capacitor removes the 386 output 4.5v DC bias meaning the positive swing seen by the LED is 0v to nearly 4.5v. The LED has a Vf of 2v, so only 2.5v needs to be absorbed by the CLR. Ohms law tells you that R=V/I so 2.5/.04 and nearest standard value R for that is 68R.
40mA is a huge current for the job a vactrol LED needs to do, so I say we can raise the 68R somewhat and also protect against the worst fault state it might encounter. I'd say the worst state is a short to the +9v supply. Easily encountered on the breadboard or due to assembly error.
Calculating again for the 9v case with 7v to lose on the CLR is 7/.04 is close to a 180R value.
Thanks very much - I missed your first edit, but I'll add a 180r resistor after the 2.2uF cap now. I'm going to place an order for parts tonight so that can be on it! I'm not going to use an NSL32 now, I got much better results with the ultra bright white LED and LDR (mainly because I hadn't fried those) but also because I can see they are actually working, which I couldn't see so easily with an NSL32.
Quote from: duck_arse on July 16, 2017, 10:42:41 AM
for moids eyes ONLY - http://i.imgur.com/PyToWOn.png
Yikes, that looks fiercesome! I suspect that it's powerful enough to become sentient and might chase the neighbourhood cats up a tree while barking in a metallic ring modulated sort of fashion! Is this the schematic equivalent of What The Butler Saw? Nobody else look, I'm admiring the poetic form and aesthetic set of massive.... resistors on that circuit. This could be art - I can't understand it; and that's my usual way of deciding whether something is art or not :)
Quote from: duck_arse on July 16, 2017, 10:42:41 AM
if you, moids, have a butchers at the circuit linked, find IC4 where it says "CV mod". the mod is next the title box, and shows how to wire an LDR to the CV input via a switch. (let's ignore SW7 for the moment, connect the ldr straight to pin 5.) now when you shine light on that ldr, one position will make faster, the other will make slower. from memory. the lisght can come from a led driven by the lm386, or from ambient with your hand waving, whatever.
Okay... so I should use this LDR setup instead of the 1uF or 10uF capacitor idea you posted before (it makes a pretty good noise though... hmmm I could probably have both though! As long as they are on separate switches I might as well! I'd probably use the light inside the box itself, ambient light LDRs seem likely to make annoying constant noise when you don't want them to. One question - what is the symbol above the switch itself - it looks a bit like a letter T with a handle on the left side of it - I can see it on other switches; does it denote a SPDT or something else? By the way (in case it's important) IC1A is missing some text saying what it is in your schematic. See - I do look sometimes :)
I think I'll try multiple LEDs for extra brightness though to see what that gets me.
Quote from: duck_arse on July 16, 2017, 10:42:41 AM
run out of ldr's? get those bung nsl's you kilt, and carefully cut-off the led end. should be a semi-light-shielded ldr in there somewhere.
Now that's just plain cunning - and there I was, about to snip the legs off them to use as rather long jumpers (as I sometimes have the need). Time to find me a knife and start cutting.
Quote from: duck_arse on July 16, 2017, 10:42:41 AM
pins 1 and 8 are connected together by a wire. you won't get any more gain by sticking a cap in there instead. it might make it less bass responsive or something. and if you are going higher than the 1k trimpot, make sure you CLR.
I was looking at the top of page 10 of the datasheet for the LM386 and it shows if you put a 10uF cap between pins 1 and 8 you get a 40dB boost, if there is no cap you get 20dB as described at the bottom of page 8. http://www.ti.com/lit/ds/symlink/lm386.pdf (http://www.ti.com/lit/ds/symlink/lm386.pdf) Have I got the wrong end of the stick again? I must stop grabbing the end that's on fire... I might try it just to see what happens as soon as it gets dark here!
Quote from: duck_arse on July 16, 2017, 10:42:41 AM
I SAID - how are the ears?
Half Past Four! You don't have to shout so loud, I'm not deaf you know :) As long as everyone speaks through the medium of whalesong I can hear them perfectly... luckily the wind sound in my ears seems to have dissipated, thanks!
I tried two LEDs this evening and that really improved the squeal of the synth. Duck I will try your mod soon, honest! I found that the sensitivity knob is more of a bias - depending on where you set it in the sweep will give you greater or weaker results. I also tried bass guitar and had to change the setting for the pot to trigger the synth sounds.
moid - the little T handle is meant to indicate toggle, as opposed to a push.
and a correction - the ldr to the CV pin doesn't run faster OR slower, it runs faster with light, or faster with dark. one side works at a lesser rate than the other, and you probably want a good low swooping resistance ldr. also, if you look at the switch I said to ignore (SW7), the "to_osc" connection is just screaming for a cap to the lm386 output. then you have 386 cap//none//ldr modulation, and dark fast//light fast on the other switch.
as for pins 1 and 8, none of the datsheets I've seen mention shorting the two pins, although they show them thus in the "square-wave oscillator". I don't know what this means. cap, no cap, your choice.
as for the turpo supinant, it doesn't have enough switches. I couldn't keep at it because I got sick of the basic sound. it does some fab gliding up/down and faster/slower decays, at its own whim, depending on where all the divider connections are (those rotary switches, SW1 and SW2). most of that circuit has me baffled, now.
[edit :] strikethrough.
the more I think about this, the wronger I get. the CV pin is the 2/3 tap of the internal R//R//R divider between Vcc and ground, used to set internal trigger points. this is why the ldr in one direction has half the effect of the other direction. as to what it does vary ..... I give up. one day I'll BB it and then I'll know for sure, but not today.
and about that cap from the 386 to the CV pin - I don't know why the connection would cause audio noise, especially pickup dependant, but, seeing as one end is connected to 2/3 Vcc (the CV) and the lm386 output sits at 1/2 Vcc and swings wildly more and less than that, maybe connect any electro cap you fit with the (-) lead to the trimpot side of the 2u2 cap, and the (+) lead to the CV pin.
I've not played with this thing either - have an aversion to 555 circuits for some reason, though I do have some in the parts drawers.
I always assumed it's a PWM & ring mod type effect. The LDR is changing the timing of the 555. Note the "vactrol" control has no envelope cap, so it's meant to be wiggled by the input signal frequency. LDR's are slow reacting though, having some persistence of vision, so I'd have thought it would only work, if at all in ring mod fashion with deep bass notes. The output signal also resets the timer, so I guess there is an element of PWM control feedback with the LDR controlling pulse width . With the feedback from threshold to trigger the 555 ought to be free running as an oscillator. So how does it shut up when playing stops? I guess it relies on the reset level on zero input signal acting to stop the 555 timing.
today! yes, I've also concluded the reset level allows/mutes the oscillations. and I've put the basic on the bb wit der cro, and found some other things. turns out the duty cycle is only a little off 50% across an ldr range of 10k ~ 220k. with the 4k7 and the 47nF cap, ldr of 10k gives a freq of 1234.567901 Hz (astoundingly, according to my calculator), at 56k its 264 Hz and at 220k its 69 Hz.
but wait - I have a picture:
(http://i.imgur.com/xxQBwbM.jpg)
with a 4k7 and 56k (ldr) and 47nF, the middle, red trace shows the output, about 263Hz. pulling the CV pin to supply with a 47k gives the top trace, now 200Hz. the bottom trace has CV pulled to ground via 47k and a freq of 400Hz. the left of the screen shows the "t2" time doesn't vary worth bothering, and the shift is in the "t1" time. [obviously the t1 shift amount will vary with the resistance strung to +/0V as well, but I haven't mapped that.]
so now it's for moids to string it all together and tell us how it sounds.
Thanks very much for the work you've both been doing around this circuit. I'm really sorry about my lack of replies, I'm not going to get a chance to look at things until the weekend; on Tuesday one of our management team managed to drop a bombshell on my department and has screwed us over for the next calendar year, possibly longer and so every hour of the day and night since myself and one of my colleagues have been trying to come up with disaster plans to cope with the screw up... and I've been doing that until the early hours every night since :( It's one of those problems that has no good solutions; only shitty ones and it's a case of trying to work out which shit solution does the least amount of long term damage to us... and I thought I was going on holiday next week :( le sigh...
No news is good news? Not quite, alas... OK after last week being a giant disaster I thought, it's the weekend, I'm bound to get an hour or two to do some work on this circuit on Saturday... lo and behold the worst thunderstorm for a year meant that our sewer backed up into the garden/patio, and I had gutters / downpipes fountaining water everywhere... oh joy, I get to spend far too much time disinfecting stuff and digging crap out of drains and pipes - silver lining; at least this time it didn't go in the house! It's now about 11PM, everyone else here is finally asleep, I think I'll have a go at some of the mods... and half the circuit (the LDR / LED part) seems to have died. None of the LEDs are working, the LDR doesn't seem to respond to light (when I shine a torch on it in a dark room). I should test this, but in my current frame of mind I'm considering throwing the bloody breadboard out of the window. I've tried cursing furiously, I think I'll leave this one alone until I feel calmer...
I think Bob Dylan might have been thinking of me when he sang:
".... there's no success like failure
And failure's no success at all"
Oh and I had to cancel three days of holiday next week for more planning problems at work. Grrrrrrrr I think I will just blast my guitar through some fuzz pedals and hope the universe stops playing tricks on me next week. Watch this space!
OK some sort of an update. I couldn't get the LEDs to light up. I tested them - they are fine. I tested the LDR, it works as well. I checked the voltage to the LEDs and they were only getting 6mV... weird. traced back to the LM386 and it's only giving out 3.4V on pin 5. That is odd. Traced to the powerjack in and it's at 3.5V What??? Then put my hand on the plug on the mains (thinking maybe it's loose and not enough power is getting through) and OWWWWW - burned my fingers! The bloody plug is red hot and the back of the case fell off! Yes, I turned off the mains socket switch before prising the plug out of the socket. Well that's dirt cheap daisy chain plugs for you I guess... time to buy a slightly less cheap one.
I switched to another (less flammable) daisy chain plug and power was restored, but still not lighting the LEDs. I had switched out the 150R resistor to a 120R as it should be and also switched the 100pF to the 82 pF on the TL072 but neither of these should've caused an issue (the 82pF sounds to me like I can hear more treble, might be me imagining things though, but it seems brighter). Using the DMM I worked out that as soon as the signal went from pin 5 of the LM386 and into the 2.2uF it dropped to only a few mV - around 6.5 of them which won't light a fart, let alone an LED. I removed the 2.2uF and the LEDs burst into light (there is an 180R resistor still between the LEDs and pin5 in case you were wondering if I was going to blow up some LEDs). Adjusting the Sensitivity knob allows for anything from no extra synth sounds to slight amounts of synth (sounds like the original pedal), to too much of the LM386 only, and after about 2/3 of the sweep there's no discernible difference in sound. So.... this works, but I have to remove something that is on the original board to do so (the 2.2uF from pin 5 of the LM386). Is this is a good thing or a bad thing?
I tried a 1K pot but the range of usable sweep was much more narrow, so I think I'll stay with 2K.
Duck, I will try your mod soon, just needed to get the circuit working first.
what was the cause of the wallwart meltdown - you need to find that and clear it before you go all fukishima again. when you were measuring the volts after the 2u2 cap, you were switched to V AC, weren't you? cause a DC voltmeter won't make a lot of sense of AC volts, and vicie versi. the cap is [blocking] at the output of the power amp (386) because the output sits at (swings about) Vcc/2 when there is no input, which will waste power if it has a DC path to ground.
put the cap back in, find out why its not werking rite.
OK so I didn't get much chance to do much tonight. I got the 2.2uF cap back in and with a decent power supply, what do you know, it works :) Having said that, the sound of the pedal is more extreme without it, so I might place it on a switch to switch the circuit through it or bypass it. I also tried a blend of the final output and pin 3 of the NE555 so I could have just the synth side of the pedal if I wanted it, but I think it's fairly subtle and not worth the effort.
The insides of that wall plug are weird. There's a small PCB with through hole components with about 3 or 4 diodes on it and one of the largest capacitors I've ever seen, plus some sort of heatsink, then that lot is glued with epoxy to a slab of metal with wire coils inside it. Might be able to salvage the diodes, they've been put in vertically. The heat sink is attached to something, maybe something like a 7805? I'll have ot dismantle it to look. The inside of the plug itself is partially melted and there are some burned pieces of paper and sponge foam in it!
Hopefully tomorrow I'll try to understand your mod.
Duck, you're some kind of genius :) I got your mod in and it appears to work - at present it's on two switches like your drawing, and depending on how you arrange the switches the guitar either quacks wondrously or makes arpeggiated squeals... and if I switch between neck and bridge pickups there's more variation. I had better draw this thing up before I forget what I did!
I still think I want to add a clean boost to blend with this pedal. I was wondering if I could try something like Tim Escobedo's Duende:
(http://www.diale.org/tpe123/duendejfet.gif)
But because this has a single transistor, does this mean it will invert the phase of my clean signal and then when I blend that into the rest of the pedal's audio output it will go rather quiet instead of loud? Would the best be to build another Mr Black Tiger Boost which doesn't invert signal? Thanks!
ahem. and I "
QuoteDuck, you're some kind of genius .... either quacks .... or .... squeals...
excellent. glad to be of service. and yes, the single transistor with output taken from "above" (collector or drain) will invert, from "below" will follow (emitter, source). as for whether the out of phase clean will buck or boost the output is unknown for this circuit. you'll be a pathfinder.
let me draw something overnight, might replace the 386 and provide clean/boost.
Wow, thanks, but please don't feel the need to rush this, I'm sure you have tons of your own work to be getting on with... hmmm I think I have an idea about what you're planning - are you thinking about swapping the 386 for a dual op amp IC? So that one half does what the 386 currently does and the other half is a clean boost? That sounds cool...
alternatively if you want a laugh at the current state of the circuit check out the below:
(http://i.imgur.com/z1K1YbO.jpg)
She's got a face only a mother could love; but she only works in the dark so it's not a problem for me :)
PS my son and I saw some of your namesakes on the river near us today, they seemed quite content with their new brood, but freaked out when a buzzard came over.
^ she looks nice, does she have a sister?
it's too late, I've done it. this is something I've sent you previous, but modified. I've used it elsewhere, Kipper 'the postman' and I messed it up a while back. it doesn't show the 555, but you just need to feed in, feed out and shine the led on the ldr, no other changes in that section. I'm not sure about how well the mix will work - if Jim or someone is looking, they might advise.
so, we chuck the LM386, and replace with an LM358 (built for the task, but most any opamp will work). the first stage has some gain, and feeds the clean mix pot and the rectifier section. the attack and decay and gain and ripple of this section are all parts/adjustable, or panel pots, or fixed, as you like them. the led now drives bright-to-dark on decay, or dark-to-bright on decay, via the switch. I think I've got enough gain to match the original, but you'll tell me either way.
it is special big, just for you. colours - just for me, let me know if they no good.
http://i.imgur.com/po4RgvW.png
[edit :] I should also point out that the Vcc/2 on my dia is the same as from the original circuit, I think it was 2 x 56k and a 10uF. connect all the Vcc/2 to that point, and note the rect sect has its own ref V.
Dry mix might be useful if you can pick it's polarity. Effect sound is (should be) so out of whack compared to dry you probably won't ever get silent phase cancellation.
We recently obtained 2 ducks. Still waiting for them to lay eggs which is what they are for. Built a nice pond for them and they won't go near it. Buggers are aquaphobic.
Quote from: duck_arse on July 29, 2017, 11:03:12 AM
^ she looks nice, does she have a sister?
I'll put in a good word for you Duck; being your wingman is the least I can do :) I have to warn you, she likes to get tied up with cables and can get very loud!
Quote from: duck_arse on July 29, 2017, 11:03:12 AM
it's too late, I've done it. this is something I've sent you previous, but modified. I've used it elsewhere, Kipper 'the postman' and I messed it up a while back. it doesn't show the 555, but you just need to feed in, feed out and shine the led on the ldr, no other changes in that section. I'm not sure about how well the mix will work - if Jim or someone is looking, they might advise.
so, we chuck the LM386, and replace with an LM358 (built for the task, but most any opamp will work). the first stage has some gain, and feeds the clean mix pot and the rectifier section. the attack and decay and gain and ripple of this section are all parts/adjustable, or panel pots, or fixed, as you like them. the led now drives bright-to-dark on decay, or dark-to-bright on decay, via the switch. I think I've got enough gain to match the original, but you'll tell me either way.
it is special big, just for you. colours - just for me, let me know if they no good.
http://i.imgur.com/po4RgvW.png
[edit :] I should also point out that the Vcc/2 on my dia is the same as from the original circuit, I think it was 2 x 56k and a 10uF. connect all the Vcc/2 to that point, and note the rect sect has its own ref V.
Thanks very much! I have a few questions (of course). I'll need to order some parts to make this, never used an lm358 before - just out of interest does this op amp behave differently to something like a TL072? I looked at the data sheet and they seem fairly similar, but it seems to potentially provide a huge amount of dB? maybe those numbers are just theoretical, but that opamp sounds like it could make a damn loud clean boost on its own. Would this be cleaner than a JRC4558 or TL072 for example? I know you said parts could be swapped, but I get paid in a couple of days time so I can go wild and buy some parts (yes folks, just living the dream here!)
Am I right in thinking you moved the diode (yours is a BAT46 - is that an important part to get?) so that now protects power to the whole circuit whereas before the 1N4001 diode only provided protection to one IC?
If you don't mind I'll post a vero layout for this once I've drawn it (too late to start tonight and I must build the four way splitter pedal I need before my wife insists that she gets the kitchen table back and I have to clear up)
Thanks again :)
Quote from: anotherjim on July 29, 2017, 05:00:45 PM
Dry mix might be useful if you can pick it's polarity. Effect sound is (should be) so out of whack compared to dry you probably won't ever get silent phase cancellation.
We recently obtained 2 ducks. Still waiting for them to lay eggs which is what they are for. Built a nice pond for them and they won't go near it. Buggers are aquaphobic.
Thanks anotherjim - I was aware that a single transistor in a circuit would invert the phase of a signal, but can other components also do this?
All the ducks round here seem happy with a life aquatic, maybe yours just had a bad upbringing? It's best to blame the parents in these situations. Or maybe they think they're chickens?
A spare op amp can invert without necessarily boosting. Either an op-amp or transistor stage an take the signal through a second inversion to give 2 opposite phases.
Duck alluded to single transistor cathodyne/concertina/phase splitter.
(http://electriciantraining.tpub.com/14180/img/14180_40_1.jpg)
If R2 & R3are equal, then you have two anti-phase outputs.
The green ringer uses just that with Q2.
(http://www.beavisaudio.com/schematics/Images/Green-Ringer-Schematic.png)
Put each output (after the caps) to opposite ends of a pot, then when the wiper is in the middle the signal cancels out. At each extreme of the pot it's either inverted or non-inverted signal on the wiper. Then take it to something that mixes it with the effect sound.
The effect sound might be too strong compared to dry, so some juggling of the levels will probably be needed.
alluded? deluded, more like. the BAT46 is just hanging around from the circuit dia I was recycling. it is not terribly important, any schottky will do for their low forward voltage. you could also use a 1N400* in series, or reverse parallel, if you like.
the LM358 is optimised for single supply, low voltage, so goes well w/ 9V, and also allows its inputs to go down to ground. it is a better performer as a rectifier/driver than as a clean audio part (I allays see a big step/glitch in the output w/ audio). again, it is not important, but is a better choice than the TL0** series.
I am always happy to look at pictures of people's pet ducks.
Will be back with this one soon chaps, had a minor disaster this week with the sewer that runs behind and under my house deciding to erupt and flood the garden and garage, so have spent this week doing DIY to fix things before the next storm... we have more torrential rain predicted for tomorrow so we'll soon see whether I'm a better sanitation facilitation engineer than pedal builder... fingers crossed.
One quick thing I did build though that I have a question about (a ZVex Super Hard On). I need a boost for the buffer/splitter circuit I'm building and I was desperate to do something this week that wasn't unblocking drains / disinfecting stuff and was simple enough to do late at night, so I built this on vero board and it works (yay, a rare surprise) but... it has a fair bit of crackle to it when I play chords and some individual notes. I did have to make a couple of parts substitutions, so maybe those have cause the issue? (it's not the crackle OK thing when you turn the knob, this is when you play every note). It's not boxed yet and the offboard wiring is held together by lots of crocodile clips and jumper cables, so maybe it's that? The parts I substituted were a 5K lin pot for the 5KRev Log pot the circuit should have (I thought it's the same level of resistance, but the taper will be different, however that lack of rev on my pot is making wonder if that is important) and I had to switch the 5k1 resistor to a 5k6 because that was the nearest resistor I had to that value.
Here's the layout I used:
(http://2.bp.blogspot.com/-iG7wRTYtG0U/UR1l_HsMnEI/AAAAAAAAE4Y/h_oe9Dm-7lw/s1600/ZVex+Super+Hard+On+-+Compact+Layout.png)
If this one means nothing to either of you I'll try to post this as a new thread in the forum in case anyone else has built one and had problems. I can get the part substitutions in a couple of days now I've got paid.
it shouldn't crakle. if it was misbiased/less than optimal biased, it might clip half the signal. any chance you've wronged one of the 10M resistors? please post your voltages - supply, drain and source. the gate voltage will be weighed down by the meter against the high-value resistors, so is less meaningful. photos of build?
a resistance of 5k is a resistance of 5k. doesn't matter if it's a 10W wire wound resistor or a W taper pot, it will still work as 5k of resistance. a B taper will be seem to be at max gain for half its rotation when used as in the sho, whereas the C taper feels best to most.
[edit :] I'm think I've confused my tapers - the B would come on sudden at full rotation used in a sho, like an A taper used where a B was best suited.
and - you can fake a C taper if you can live without the lowest gain settings. for a C5k, you could sub a B1k with a 3k9 from CCW to ground, and the bypass cap to the wiper and ground.
I think a reversed/bad electro cap in the signal path can crackle like that. There is only the one - 10uF output - in that circuit.
I don't believe value substitutions could cause it.
Live sewage might :icon_eek:
Thanks chaps, after a lot of testing it seems the little circuit only crackles weirdly when attached to my very crappy test amplifier, but doesn't do anything weird when attached to my bass amp or my PC... so I should've tested it elsewhere before asking, sorry for wasting your time. The circuit doesn't create a clean boost like I thought - from looking at the waveform recordings I've made it's clearly very asymmetrical so that adds distortion when I play chords / anything too loud. I then ran 18v into it instead of 9v and the volume got louder (good) and also slightly less distorted (also good), but still too distorted for a clean boost. I then tried a Mr Black Tiger Boost at 18v and it does indeed get louder and stays clean, so I'll be going with that circuit I think. I may try swapping the JRC4558 out for an OPA2134, I'd read on the gearslutz forum (I think) that this opamp should be cleaner and possibly louder, which is what I'm aiming for. It happily has the same pinout as the 4558 so I'll socket them and do some testing once the parts arrive.
Thanks for your advice - I'm going to get the correct parts for the SHO and even though I'm not going to use it for this purpose, my son was playing with it and fed an old Shin Ei FY2 I built when I first started making pedals into the SHO and loved the immense blast of sound the SHO got from it and said "Daddy I need these two pedals in one box with two switches, how fast can you make one?"... no pressure of course :)
Luckily the rain wasn't as heavy as forecast - some thunder and lightning but nothing torrential... so far my DIY water routing skills seem to be working. And I saved £400 on not calling out Dynorod to dredge the sewer (there are tree roots growing in it; I hacked them out, pretty smelly job but £400 is £400... and I needed to buy new glasses this month so that's where the money's going!). My advice to anyone who wants to buy a house with an extension built over a sewer is don't buy the bloody house... the sewer needs rebuilding (it's old and busted up) but to do so would require the water company to knock down half my house to get at it... the extension was put up at some point in the early 1980s with no planning permission (understandable; it wouldn't have got permission if they'd asked for it) and was fine at the time, but now the pipes underground are 60 years old they need fixing and there's a limit to what anyone can do without digging them up.
OT:
> new glasses this month so that's where the money's going!
zennioptical.com - two pair single-vision, shipped, for $19 -- I'm seriously happy. Frames (metal aviators) are good, http://static.zennioptical.com/images/product/41/90/419014_lg.jpg , strength (focus and astigmatism) is correct, no hassle, delivery just over a week. I do not know if off-shore prescription glasses are legal in your country.
The single-vision may sell at a loss. Bifocals cost very significantly more. I thought I would go that way, but instead use pound-shop (Dollar Tree) readers for close-in.
EDIT-- digging, I find I can get with-a-line bifocals for $24 (+$5/order shipping). This is low-index which is fine for my mild prescription. They still push high-index, tints, etc, so I can spend $58 even before they offer coatings, clip-ons, engraving... I can touch $80. Which is still 1/5th what a lesser package would cost downtown. And I am suspecting that all eyeglasses come from the few asian shops. The business is highly consolidated.
Thanks very much PRR, that site is indeed seriously cheap! Sadly they don't cater for the special prisms I have to have in one lens to reduce double vision and to cut down on the colourful halos I see around bright objects (one of my eyes is really @#$%ed, but slightly trippy - if I ever get bored, I close the good eye and stare at bright things and watch them become psychedelic!) and although my glasses are very expensive, I'd still like to get them from the local store who I've known for years (they aren't a chain) and who have helped me immensely in the past with spotting problems and getting me referred to the right consultants for help. We just lost the only decent guitar shop for miles (closed down because people buy their guitars online now, a real shame, the two guys who ran it had been doing so for about 30 years and were amazing) and I definitely believe in supporting local businesses if I can versus corporate mass chains. I do appreciate you taking the time to help me though, thanks very much. I can see this being a good price to people with more 'normal' vision issues. I hadn't heard that some countries have a ban on off shore prescription glasses; I don't think the UK has, but then again I've never asked! That's pretty harsh.
OK, yes, prism is uncommon, not a standard product, not easy to know when the lens-grinder gets it wrong. I can certainly see getting that need handled locally.
I was somewhat nearsighted, then lost accommodation, so was on mild bifocals to see far and near. Cataracts spoiled that so now my eyes are brownie-cameras- fixed focus at a distance, and not exactly. I can drive without glasses (first time in my life), but part-Diopter corrections make distance better. And the same on a +1.5D base is excellent for the PC.