Can someone take a look at this?

Forum dedicated to helping people debug and troubleshoot non-functional pedals or builds. Please use an clear and informative title, indicating circuit and basic problem. Don't forget to mark the issue as fixed if this is the case.
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Ellipsis
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Joined: 29 Jun 2020, 06:05

Post by Ellipsis »

First, I should preface this by saying that I'm new to pedal building, and electronics in general, so go easy, please. I've been studying up and building a few kits, as well as premade PCB pedals, but as far as design, this is uncharted territory. The following is my first ever schematic and layout, and what I'd be very grateful for is if someone wouldn't mind looking it over, and tell me: 1. any obvious mistakes I've made, and more importantly, WHY it's a mistake, so I can learn from it; how I could possibly improve upon it ( I tried to follow the advice R.G Keen gives in his 'PCB Layout' book); and most importantly, I'd really like to know that if I built it according to my layout, WOULD IT WORK?

DISCLAIMER: this pedal is NOT my design, but one that I became interested in, that I stumbled upon on the internet. I've included his original schematic and layout, as well as mine, for comparison. One "verified", so to speak, I will credit the original creator.
Attachments
layout.png
fuzz schem.png
original layout.jpg
Inkedoriginal fuzz schem_LI.jpg

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FiveseveN
Cap Cooler
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Post by FiveseveN »

Well it's a good thing you asked. I was going to "fix" your schematic but if your goal is to learn it would be more useful to go through it step by step.
The Bazz Fuss was my 1st working project too, by the way.
elipsis.png
1. I'm assuming SW2 is supposed to bypass the effect, right? If "bypassed" means "does not influence the signal", then your switch must come before the high-pass filtering capacitors and the bypassed signal should "exit" after what I'm assuming is a volume control. Right now it's going nowhere (out of SW2 pin 5). Just look for "true bypass switch (wiring)" or any schematic with TB for an example.
2. The "to vol" signal goes nowhere (not that it should).
3. When not in "bypass", your signal is getting shorted to ground (highlighted in green) so you will get no input, thus no output.
4. Your diodes aren't going to do anything (highlighted in red). One side (either pin 5 or 8 or SW3) is correctly connected to the collectors, but the other side (pin 8 or 5) has to be connected to the base of Q1 (green signal). You also don't need to switch both sides, but that's a topic for later.
5. The volume control might do something but it's not going to be very effective. It makes more sense to wire it the usual way (output from wiper), see the original schematic.
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

Ellipsis
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Joined: 29 Jun 2020, 06:05

Post by Ellipsis »

First off, thanks a million for taking the time to explain this to me. There was much more that I should have included in the original post, since I did already attempt a build according to HIS original layout (pic 3), but the problem I ran into was that the true bypass switch/wiring is missing. I used a method I found that seemed to make sense, but (as expected), it isn't working properly. I'm currently in the process of debugging the pedal using my meter and a probe (the latter is actually teaching me A TON about signal flow). I'll certainly look into the things you pointed out and report back. Again, thank you for taking the time. Truly appreciated.

Ellipsis
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Posts: 7
Joined: 29 Jun 2020, 06:05

Post by Ellipsis »

So I've made the suggested changes (I hope, and I've also only updated the complete layout and not the schematic, since the layout is the ultimate goal anyway, as I'd like to build this). I have: 1) laid out the wiring on the first 3PDT for true bypass (again, I hope...), placing the dry signal BEFORE the input caps on the toggle switch, and also ran the jumper from pin 1 to pin 9, instead of pin 8, which went to ground. 2) I've moved the output of the second 3PDT (SW3) coming out of pin 8 into the base of the transistor pair, (hopefully) now making the diodes operable. 3) bypassed the volume pot altogether with the dry signal off of the first 3PDT, and moved the input of the effected signal going into the volume pot to lug 3, now taking the output of the volume pot from the wiper (lug 2). Fingers crossed that this works. After having these mistakes pointed out and corrected, they seem so obvious now, but I just couldn't see them before. Thank you again.
Attachments
layout 101620.png

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