I think I'm going crazy. HELP!!!

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TV-Set
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Post by TV-Set »

Guys, I'm losing it! I need help, either that or I'm gonna commit a suicide!

I made this circuit for a friend and it work fine on my breadboard, but as soon as I solder things together it sounds really bad! Lotta hiss and noise, kinda like high pitched white noise sound. Even when I get rid of it by lowering the fuzz the sound is still very distorted (in a bad way). I also tried a sound probe an by probing the very input of the circuit what should've been clean is kinda clean but with that hissing distortion on top, sounds like someone's squizing the pedal's balls... I already built it twice as I thought that maybe the problem was in the componets or the board. So I went and made the pcb perfect and used the componets from the freshly tested breadboard... HISS!!!
I'm posting pics for the pcb I designed, the circuit and the built board.

Is it the PCB that is f*cked up?
What did I do wrong?


PS: R11 is ommited
Mids pot lug 1 is connected to Tone pot lug 3 via R5 offboard
V = Level pot
T = Tone pot
B = Bias pot
F = Fuzz pot
L = LED indicator
V+ = Voltage LED (Q2 bias) positive lead (note that in the PCB R3 is before this LED) the negative lead goes to gnd
Tc = Touch pot
3PDT switch is soldered directly to pcb
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Seiche
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Post by Seiche »

maybe the board layout itself?

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TV-Set
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Post by TV-Set »

Seiche wrote:maybe the board layout itself?
I dunno, it well may be, I checked it a 100 times, that's why I'm so desperate. I tend not to notice the most obvious things. If somebody could just take a look if the board layout is ok... :cry:

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Post by Seiche »

well I mean because of the parallel lines or something. I have no knowledge in analysing this though.

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TV-Set
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Post by TV-Set »

Seiche wrote:well I mean because of the parallel lines or something. I have no knowledge in analysing this though.
lol, no, the pcb is perfect build-wise. no bad junctions, all the threads are well separated from the nearby ones, solder job is good too. The layout might hide a bug cuz it works on the breadboard... been working on this for at least 2 weeks now, so f*ucking frustrating! this is my pedal n5 so I'm no guru but I never had anything ike this happen to me... :cry:

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Post by Nocentelli »

I don't think seiche is suggesting the pcb doesn't match the schematic/breadboard layout, or that poor soldering/construction is to blame: It is not unknown for the routing of a pcb layout to introduce problems, with long stretches of parallel traces (particularly carrying in+out signals in close proximity). The offboard wiring can also potentially cause issues, which is why I believe shielded input+output cable is sometimes used. I have no experience of pcb design, being a veroboard pervert, but I have built a layout of a circuit that oscillated like crazy at high gain in an awesome way (gilmour pugliese's lunar module deluxe). My own vero layout is squeal-free, and I can't replicate it on the breadboard. You could read up at DIYSB, I've seen it discussed several times.
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Post by DrNomis »

It could be that the +V supply isn't properly bypassed to circuit ground via a 100uF capacitor, my other thought is that somehow the output signal is getting back into the input and making the circuit oscillate at a frequency above what we can hear, this usually manifests itself as a hissing-sound and very dirty sounding output that doesn't sound quite right.... :thumbsup
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Post by TV-Set »

Yes, I am starting to think it's in the layout itself, maybe some traces interfere with eachother electromagnetically... damn, it took me 5 days to route this sucker :evil:
Is anyone good at Eagle or something and can make it with ease?

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Post by bajaman »

are you running this from a battery or a dc plugpack supply ?
if you are running it from a plugpack, try inserting a 100 ohm resistor in series with the +ve input on the board and then connect a 220uf capacitor from this junction (+ve terminal of capacitor to +ve terminal on board) to ground as a bypass. :wink:
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Post by TV-Set »

bajaman wrote:are you running this from a battery or a dc plugpack supply ?
if you are running it from a plugpack, try inserting a 100 ohm resistor in series with the +ve input on the board and then connect a 220uf capacitor from this junction (+ve terminal of capacitor to +ve terminal on board) to ground as a bypass. :wink:
bajaman
I tried that already, both cap and R are present in the schematic. The thing sounds the same with DC jack or a battery when it's on the b.board and gives me shit on the pcb :scratch:
Yet again, the problem is NOT in the schematic, I think I mastered that bit and can do my own circuits now and they sound just as I want them to.

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Post by The G »

I flexed my tracing muscles a little and look what happened. Tell me, how far is my schematic from yours? It appears that you're using both a resistor and a LED to limit the lower value of the bias voltage for Q2. Am I right?
I tried to keep original parts locations, but not too hard :mrgreen: .
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fuzz_tv-set_v2_sch.png (8.05 KiB) Viewed 2758 times
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fuzz_tv-set_v2_pcb.png (7.44 KiB) Viewed 2758 times

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Post by DrNomis »

ggedamed wrote:I flexed my tracing muscles a little and look what happened. Tell me, how far is my schematic from yours? It appears that you're using both a resistor and a LED to limit the lower value of the bias voltage for Q2. Am I right?
I tried to keep original parts locations, but not too hard :mrgreen: .

I have to admit that it's a bit unusual to use a Led to set the biasing of that transistor, that threw me a bit and I couldn't work out what was going on, the Led seems a bit superfluous to me, because I think the circuit should work fine without it.....maybe I'm missing something here.... :scratch:
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Post by TV-Set »

DrNomis wrote:
ggedamed wrote:I flexed my tracing muscles a little and look what happened. Tell me, how far is my schematic from yours? It appears that you're using both a resistor and a LED to limit the lower value of the bias voltage for Q2. Am I right?
I tried to keep original parts locations, but not too hard :mrgreen: .

I have to admit that it's a bit unusual to use a Led to set the biasing of that transistor, that threw me a bit and I couldn't work out what was going on, the Led seems a bit superfluous to me, because I think the circuit should work fine without it.....maybe I'm missing something here.... :scratch:
Well, the primary function of that LED is indicating the bias voltage (sounds like starve control) cuz bias is not a trim but a pannel mounted pot. When the LED's dead the voltage is below 1V, bright = 4.72 if I remember righ, dead to bright = somewhere between 0.72 and 4.72V. It's kinda cool to have a visual indicator of the bias and the fun part is it lights up and pulses as you play :)

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Post by TV-Set »

ggedamed wrote:I flexed my tracing muscles a little and look what happened. Tell me, how far is my schematic from yours? It appears that you're using both a resistor and a LED to limit the lower value of the bias voltage for Q2. Am I right?
I tried to keep original parts locations, but not too hard :mrgreen: .
That cat on your avatar = me when I saw the file :applause:
Holy f*uck man! That's super awesome of you!Thank you, good man! I shall examine it closely when I'm not stoned. But damn, this bitch's just asking me to etch the f*ck out of it :mrgreen:
Just one Q though, u sure all that GND around won't inerfere with the signal? I just wanna do this once and make sure it works :horsey:

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Post by TV-Set »

Yeah, I'm looking into it now, I kinda like that it's much smaller than mine. Also, I noticed something that I don't understand - why's Fuzz lug 1 isn't grounded? Is that not necessary and I always put 1 wire more than what's needed? :mrgreen:

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Post by The G »

The FUZZ lug 1 is not grounded because that's how I interpreted your layout, I only saw two FUZZ lugs. Looked like variable input impedance to me (keep in mind your layout does not have values so I resorted to lots of interpretation).
Dr. Boogie has a lot more gain and uses the ground almost-plane in a similar manner. So I wouldn't be too concerned with side effects.
Except if I misunderstood your question.

You didn't tell me - how far is my schematic from yours (being traced from a layout with no values and all that)?

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Post by DrNomis »

TV-Set wrote:
DrNomis wrote:
ggedamed wrote:I flexed my tracing muscles a little and look what happened. Tell me, how far is my schematic from yours? It appears that you're using both a resistor and a LED to limit the lower value of the bias voltage for Q2. Am I right?
I tried to keep original parts locations, but not too hard :mrgreen: .

I have to admit that it's a bit unusual to use a Led to set the biasing of that transistor, that threw me a bit and I couldn't work out what was going on, the Led seems a bit superfluous to me, because I think the circuit should work fine without it.....maybe I'm missing something here.... :scratch:
Well, the primary function of that LED is indicating the bias voltage (sounds like starve control) cuz bias is not a trim but a pannel mounted pot. When the LED's dead the voltage is below 1V, bright = 4.72 if I remember righ, dead to bright = somewhere between 0.72 and 4.72V. It's kinda cool to have a visual indicator of the bias and the fun part is it lights up and pulses as you play :)

Ah, I see now..... :thumbsup
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Post by bato001 »

I am a little late to the party on this one, but I have to put in my 2 cents LOL. My first PCB design was for a Modern Swollen Pickle clone and I did the same as you TV. I routed shit all around the outside with long traces running parallel and the hiss was very distinct and made the pedal unusable at high volumes. I then read the article attached below and re-did the layout accordingly and the the new PCB was quiet as a mouse even with my amp cranked to club levels.

Awesome idea with the LED by the way. LOVE IT.
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Post by TV-Set »

ggedamed wrote:You didn't tell me - how far is my schematic from yours (being traced from a layout with no values and all that)?
Woops, I didn't realize you missed the schematic pic I posted right in the beginning, strange, it won't show :mrgreen:
Here's the original schematic, repost. I think if u had the schematic in the first place u would've spent much less time than with all the tracing and such :oops:
http://postimage.org/image/8426ygmcr/

So, you tell me how far is it? :mrgreen:

You can see for yourself that it's the thing. And that's why I asked about fuzz lug1, thought it was kinda strange that you "missed" that.

Image

PS: I checked the pcb u kindly made for me and it's correct. Note that as initially intended the mids pot with R5 stay offboard (mids lug 1 to tone lug 3 via R5); and Fuzz-1, Mids-2 and Level-1 are also connected together and then to ground offboard

PPS: I didn't put the values as I considered those to be irrelevant, I don't have any problems with the circuit per se, works fine. If anyone wants to try this fuzz out I can send all values and instructions. The most versatile fuzz box I tried so far (although it's designed for bass :P )

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Post by DrNomis »

bato001 wrote:I am a little late to the party on this one, but I have to put in my 2 cents LOL. My first PCB design was for a Modern Swollen Pickle clone and I did the same as you TV. I routed shit all around the outside with long traces running parallel and the hiss was very distinct and made the pedal unusable at high volumes. I then read the article attached below and re-did the layout accordingly and the the new PCB was quiet as a mouse even with my amp cranked to club levels.

Awesome idea with the LED by the way. LOVE IT.

Cheers, I'm a bit rusty when it comes to PCB design so I downloaded a copy of the pdf so I can have a good read of it....... :thumbsup


Now that I think about it, I remember designing a distortion pedal that used a couple of Leds as signal clippers with an Op-Amp stage, while I had it on the breadboard I was tracing through the circuit with a scope and found that it oscillated at a very high frequency when the gain control was maxxed-out, it seemed to be caused by some bi-polar caps I used as couplers, I touched the scope-probe tip to the metal casing of the caps and found that the oscillation signal was there, I also found that if I connected the metal baseplate of the breadboard to circuit ground, the oscillation was much reduced but still there, try as I might I couldn't get rid of the oscillation completely, the circuit even oscillated when built on Veroboard.... :thumbsup
Last edited by DrNomis on 19 Jul 2012, 16:21, edited 1 time in total.
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