Silicon Fuzz Face - OSCILLATION

[Ralfg]

Yeah, I was only thinking audio probe to see if the oscillation was happening right away or actually coming from the transistors. Something is funky and I hope you figure it out.  Your in good hands though with Midwayfair. More pictures would help. Good luck!

[Willybomb]

I had to put a 470p capacitor instead of the 10p in my Hipster to get rid of the squeal..  I'm not sure if that's what you're refering to.  Later Hipsters don't have that cap though.

[Barracuda]

So I've rebuilt the circuit on breadboard (with 2n4401s and a 1uf input cap).

I tried the 100k resistor across the Q1 collector and base and got this squelching ---

https://www.dropbox.com/s/nvw416wndydjw27/Oscillation%202.mp3?dl=0

There is no oscillation if the jack input isn't connected, and no signal whatsoever when grounded. This was the same when I tried the normal FF, and then the 100k resistor swap.

And of course, I tried the cap between the collector and base (2200pf) got rid of some squealing on some settings but lost a ton of gain (not really any distortion just saturated mush) and it returned at a lower pitch if I fiddled with the pot. These aren't dolphin noises, but I'll either get them, or this squealing in most fuzzes I've tried. I've probably tried in the range of 7-10 different circuits with pretty much these results.

[midwayfair]

There is no oscillation if the jack input isn't connected

So the oscillation sounds and behaves like positive feedback. Here's what this indicates to me: You are somehow connecting the input and output of the circuit.

Can I see a photo of your jack wiring for both the breadboard and the pedal? You said previously that you weren't sure if they were connected properly.

[Barracuda]

So at the moment I have only 3 jacks, two stereo which I'm using and have used for the perf, I just snipped the wires *I'll deal with it later*. They were on an enclosure just for shielding purposes, but I removed them for the pic.The ground on both jacks are connected to the ground bus on the breadboard, the red wire you see is connected the same on both jacks - connected to the input/output caps.

Something suggests to me the ground wire is wrong?

*Ignore the bad soldering it was my first time*
The third lug has solder/wire on it too from when I tested it as ground, though I could have tested it wrong since I was trying a million things at once..

https://www.dropbox.com/s/z3pc0qcqbkhzyvt/20170111_192438.jpg?dl=0

This pic shows where the red and black wire connects to the breadboard (to the output cap and ground bus)

https://www.dropbox.com/s/3iguihlmqmbax2e/20170111_192451.jpg?dl=0

[midwayfair]

I know I asked for pictures, but I'm going to go through how to test your jack connections on your own so that you can figure out if something's wrong.

The sleeve connection is the part of the jack that makes the little hole you put the plug through. It should connect to the sleeve (and really nothing else, but with a stereo jack and a TS cable, it will connect to the ring).

On a normal stereo cable, the ring is the next connection. It will short to the sleeve with a TS jack, but it's the middle connection.

The tip is literally the tip of the cable.

Yours look like it might be some sort of switched cable. I can't get a good look at it but it doesn't have two connectors (that is, one for the ring and one for the sleeve) while it does have a ring lug). Can you like to what you bought?

Plug in the pedal like you've been doing normally. (Meaning, reset your breadboard before the experiments.)

Get out your multimeter. Put it on continuity.

Put one probe on the tip of your input cable -- on the ACTUAL cable, not the jack. Does it beep anywhere except the input cap?

Now the output tip. Does it beep anywhere EXCEPT the output cap (this would be the volume pot wiper if you had a volume pot)?

Probe the tips of both cables. Does it beep? (That's bad.)

Test the sleeves. Do they beep for the ground connections, the other cable's sleeve, and nothing else?

[Barracuda]

I think I'm a bit unsure on if you meant cable or jack socket in the test you mentioned, did you mean on the tip of jack cable when its plugged in the jack socket? is there any link you can show me? But I did try alot of different things based around that but didn't get any beeping. I'll probably look more into that tomorrow, as its getting late here.
Is this the sort of test I should do? - https://www.youtube.com/watch?v=nxhSotfKZEE

I looked up the receipt for the jacks they were on ebay, it was labelled switchcraft stereo but theres no link available for it.

I did a little test on the jack lugs which might be useful info, and heres a closer look at them -

https://www.dropbox.com/s/c7fhdr3ubiy988g/20170111_214621.jpg?dl=0
https://www.dropbox.com/s/itsflm0nppo3a50/20170111_214705.jpg?dl=0

I shifted both the wires (red on the right, black in the middle - according to picture 1) I shifted them both left. So now the red would be in the middle and the black on the left.

I got signal, but oscillation still. I unconnected the input jack and the oscillation stopped again like before. I also tried black wire on the left lug and red on the right, but got nothing coming through.
This is all with the original silicon FF circuit like schematic on the first post.

Edit: I watched the youtube link I posted and did the same sort of test. Turns out one of the jacks beeped when I touched the ground lug and a lug which wasn't ground, it wasn't the input lug, but the one that isn't connected in the pics. (Sorry I'm confused with what lugs are labelled what at the minute haha)
The other jack didn't do that, so I'm going to assume that they're not meant to be connected?

I have another jack spare so I'll get testing it tomorrow

[mjg]

The unconnected lug and the ground lug will be connected when you plug a mono plug into it - did you have anything plugged in when you did that test?  That would explain the continuity there. 

You should be able to confirm which lug is which with your multimeter - disconnect the jack from everything (or use the spare jack you have), put one multimeter cable on the threaded metal on the outside of the jack.  That should connect to the ground lug, so find that by testing each lug in turn with the other multimeter cable. 

Then find the tip lug - put one multimeter cable on the bendy bit of metal at the back of the jack, and test the lugs til you find the one that is connected.  That one is the tip lug (or send/receive, input/output, etc). 

The third lug is useful if you want to do battery disconnection when the pedal is unplugged from the guitar, but otherwise you should be able to ignore it. 

[midwayfair]

They're not normal stereo jacks. They're switched jacks that connect the ring and sleeve when there's nothing plugged in, at least I think so based on the pictures. You can't use them for battery switching because the ring won't be connected to ground. Also, if you soldered your ground wire to the ring it won't be connected but that doesn't suddenly mean that the tips are connected.

To be honest it's probably best to get a couple mono jacks to eliminate at least one problem. And of course it might turn out to be the transistors, though I still suspect the components last.

[Barracuda]

Well I think the fact there is no oscillation when its unplugged says alot. I believe two of the lugs aren't meant to be connected on one jack which are, so I'm going to swap that jack and see how it goes. I've also got my transistors today, AC128K and BC108.

Edit:
So I did the tests mjg said, I think they were what midwayfair was trying to say, I just got a bit confused. The youtube vid I linked says it all really - faulty jack, a lug was linked to another, and I think I had my jacks wired wrong anyway. I sorted the wiring, changed the faulty jack, and bam!

Silicon FF (bias is a bit off, but easy fix) -
https://www.dropbox.com/s/g9v65q0sg2r272f/Si%20FF.mp3?dl=0


Thanks so much for your help, I would have never figured this out - I'm still a beginner.

[mjg]

Glad to hear you got it working.   

Here's a beginners project - this is the one I started with when I was first getting into pedal building.  I think it's helpful as it spells everything out and explains all the components, including the jacks. 

Might be helpful if you're just starting out and need some explanations? 

http://www.premierguitar.com/articles/21291-build-your-own-stompbox?page=1

PDF version is probably best:  http://www.premierguitar.com/ext/resources/files/DIY-PDFs/Oct14_PGDistortion_BuildGuide_Final_R2.pdf