Fuzz Face Silicon Breadboard - Oscillation problem

[Barracuda]

So, I have followed the Fuzz Face Silicon Circuit, and compared it to a few others, like Madbeans Hipster pedal and the like. Heres the one I used...


I've copied this exactly, (with different transistors) but it's possible my ceramic capacitor weren't built for the voltage, as they're very small... (I got them in a bundle pack)
But I'm still getting signal through, just oscillation no matter what I do. The jacks are connected to the ground and input/output on the breadboard (as are the wires from the battery snap) but put onto an empty 1590B enclosure, with the breadboard just sat on a flight case. I'm using a 9v battery at the minute just to get rid of any mains hum that could cause issues.

Here are the voltages I'm getting (I know that Q2's collector is biased way off, but should that be causing oscillation??)

Q1
E  =  0
B  =  0.53
C  =  1.62

Q2
E  =  1
B  =  1.6
C  =  1.8

The transistors are 2n4401, but I also have 2n2222's at my disposal, but they're similar gain aren't they? I think it could be a gain issue, but I don't see why since I've copied the circuit?
I have used a few short wires on the breadboard just to make it a bit tidier, but there are some jumpers too.. The two short wires on Q2 E & B aren't doing anything by the way.
https://www.dropbox.com/s/ia0cvgnjj7z3w44/20170107_195948.jpg?dl=0

Any ideas?

https://www.dropbox.com/s/b0k9465pf14yc5u/Oscillation.mp3?dl=0

[Gus]

It is hard to build a Silicon transistor FF like circuit on breadboard without it oscillating when the gain is turned up.
Build the circuit as small as possible with short wires and keep the input wires away or at 90 degrees to the output wires.

If you are new to building I would use a verified layout or PCB for a Silicon FF.
You could try the Colorsound one knob fuzz resistor values with the 2N222s.

[Electric Warrior]

Here are the voltages I'm getting (I know that Q2's collector is biased way off, but should that be causing oscillation??)

Q1
E  =  0
B  =  0.53
C  =  1.62

Q2
E  =  1
B  =  1.6
C  =  1.8

The transistors are 2n4401, but I also have 2n2222's at my disposal, but they're similar gain aren't they? I think it could be a gain issue, but I don't see why since I've copied the circuit?

You should have wired it up correctly, the voltages are as expected. Yes, Q2C measures very low - but Q1C measures very high at the same time because the hfes are low. You can get Q1C down and Q2C up by using higher gain transistors (particularly for Q1, but you probably don't want to have too much difference in hfe between the two). Do yourself a favour and try the 2n2222s. The might be higher gain than your 2n4401s.

Alternatively you could try a larger resistor on Q1's collector.

The osciallation may be a layout problem or caused by the transistors. You can fix it by adding a small capacitor between Q1's collector and base.

[Barracuda]

Hey guys, thanks for the replies..
I tried some 2n5088s with this with measure at about 300hfe whereas the 2n4401s were low 200s.
Still the same problem, just dolphin noises all the time even with gain down. I even tried the 25088 just on Q2, its all the same result pretty much. If i were to solder this on perfboard would I still have the issue? I wanted to experiment with different transistors and caps, so I breadboarded :/

Theres also a link to a pic in the first post of my layout, I'm pretty sure theres nothing wrong?

[Gus]

A link http://www.diystompboxes.com/smfforum/index.php?topic=114153.msg1058953#msg1058953

[Ben Lyman]

also, maybe try feeding +9v from your (battery?) thru a 47ohm(ish) resistor and throw a 100uF(ish) cap after that from +9v to ground

[Barracuda]

Thanks for the link Gus, I think some of it went right over my head. But it looks like a biasing type system? I'm very likely wrong. I have tried a big cap from +9v to ground before with no luck, but I'm willing to try again. I'm currently trying to solder this on perfboard to see if I can blame my breadboard in some way, or is that very wrong of me? I'd just like to be able to experiment with fuzzes on breadboard, but I'm ALWAYS getting oscillation unless I have a gated or 1 transistor driven distortion!

[Barracuda]

Check this out
https://www.dropbox.com/s/b0k9465pf14yc5u/Oscillation.mp3?dl=0

This is on perfboard, so I don't think I can blame the breadboard or anything around that as its making exactly the same noise as it did on breadboard. I used the 2n5088s, they were from China on ebay but I'm not sure how much that would affect anything? Theres no volume pot if that changes anything, not that I think it does. Also the ceramic 10nf capacitor is TINY, could this be a result of it not being able to take the voltage/current? I'm not sure on the power rating of it.

[Electric Warrior]

The osciallation may be a layout problem or caused by the transistors. You can fix it by adding a small capacitor between Q1's collector and base.

Have you tried this yet?

I guess it will behave much better on perf. That oscillation is quite extreme.

Are the voltages better with the 2n5088s?

[Barracuda]

I always try the cap between collectors and base, on all transistors, I always get the oscillation, just without so much highend, unless I use a - say 47nf cap, but then you're removing tons of gain too. That oscillation is on perf! voltages aren't so different I'm beginning to feel like it could be shitty cheap transistors?

[Electric Warrior]

If anything, they're too good.

I can't find any obvious mistakes with your layout.
Since it's the only modification to the circuit you made, you could try putting a 500k resistor between output and ground.

[Barracuda]

If it isn't the transistors, all I can think to blame are my ceramic caps which I don't entirely trust, or my jacks, which are meant to be stereo, but don't look like any other stereo jacks I've seen. But I can't imagine them causing oscillation? this has been bothering me for months, thought it would have been a more common occurrence, but if it isn't, then surely I have something bad? I don't like blaming equipment, but I've shown you what I've done and if everything looks as though its in order, what is there left to blame?

[Electric Warrior]

Oscillation is a very common problem for silicon Fuzz Faces, but the oscillation you're getting is really extreme. We may be overlooking something obvious.

[deadastronaut]

try this....

[Rob Strand]

also, maybe try feeding +9v from your (battery?) thru a 47ohm(ish) resistor and throw a 100uF(ish) cap after that from +9v to ground

Did you try this suggestion from Ben?

You can also get a piece of aluminum foil about the size of the bread-board, place it under the bread-board and alligator clip it (or whatever) to the 0V rail of the breadboard.

[LightSoundGeometry]

If it isn't the transistors, all I can think to blame are my ceramic caps which I don't entirely trust, or my jacks, which are meant to be stereo, but don't look like any other stereo jacks I've seen. But I can't imagine them causing oscillation? this has been bothering me for months, thought it would have been a more common occurrence, but if it isn't, then surely I have something bad? I don't like blaming equipment, but I've shown you what I've done and if everything looks as though its in order, what is there left to blame?

problem solved other than the open interference and possible long wiring

if you dig around long enough you can find the panasonic caps from .20 per unit and even cheaper in bulk ..tayda greenies work just fine for .04 per unit on low values ..you can go silver mica for close to .50

[LightSoundGeometry]

while I have you guys here on this subject , why do you only ground one of shielded run? I am not familiar with the physics of that..thought ground was ground in this case or does it cause a loop of sorts?

I had a weird problem the other day..a tone bender ripping your face off  dimed on BB , then boxed up and now noise on 9-10 ..not really osc but more noisy squealy whine if that makes sense ..putting a fresh battery in adding a 100uF cap from 0 to -9  on the rails and it stopped ..but I only have the input shielded and my out put run is no longer than 4 inches or so and on other side of box ..and I put a copper strip inside the lid

[Electric Warrior]

while I have you guys here on this subject , why do you only ground one of shielded run? I am not familiar with the physics of that..thought ground was ground in this case or does it cause a loop of sorts?

I had a weird problem the other day..a tone bender ripping your face off  dimed on BB , then boxed up and now noise on 9-10 ..not really osc but more noisy squealy whine if that makes sense ..putting a fresh battery in adding a 100uF cap from 0 to -9  on the rails and it stopped ..but I only have the input shielded and my out put run is no longer than 4 inches or so and on other side of box ..and I put a copper strip inside the lid

A MKII? A 50µF power filter cap is usually sufficient. What have you biased it to?

[GibsonGM]

while I have you guys here on this subject , why do you only ground one of shielded run? I am not familiar with the physics of that..thought ground was ground in this case or does it cause a loop of sorts?

I had a weird problem the other day..a tone bender ripping your face off  dimed on BB , then boxed up and now noise on 9-10 ..not really osc but more noisy squealy whine if that makes sense ..putting a fresh battery in adding a 100uF cap from 0 to -9  on the rails and it stopped ..but I only have the input shielded and my out put run is no longer than 4 inches or so and on other side of box ..and I put a copper strip inside the lid

If you think about ... if you grounded both ends of an insulated conductor jacket, you'd just make another ground loop! This can induce a voltage that can interfere with your audio signal.  By grounding only one end, you pretty much make an antenna, that will pick up RF and take it right to ground, keeping it out of your input.   Make sense?

Tone Bender - ya, sometimes putting things in the enclosure bends wires and stuff that now interact in unpredictable ways. They're no longer crossing at 90 degrees, but at some angle that lets them couple and start some oscillations.  Not always audible, and can eat up your level!   One theory of why that would happen, anyway.

[LightSoundGeometry]

while I have you guys here on this subject , why do you only ground one of shielded run? I am not familiar with the physics of that..thought ground was ground in this case or does it cause a loop of sorts?

I had a weird problem the other day..a tone bender ripping your face off  dimed on BB , then boxed up and now noise on 9-10 ..not really osc but more noisy squealy whine if that makes sense ..putting a fresh battery in adding a 100uF cap from 0 to -9  on the rails and it stopped ..but I only have the input shielded and my out put run is no longer than 4 inches or so and on other side of box ..and I put a copper strip inside the lid

A MKII? A 50µF power filter cap is usually sufficient. What have you biased it to?

she was sitting right around -8.77, Q3 is biased over 8 too , its not the 4.5 volt version ..on the final build I added the tagboard 10nF mod  to the input to darken it up a bit



Gibson, while I was in there I did try to straighten up any wiring. probably helped. it just shows how finicky it can be. Im doing new layouts with screw mounted standoffs and stuff and front mounting pots etc  so it feels new again working in those areas lol..you guys make it look so easy, some of the eye candy porn, like in the post your gut shot section , are like trying to recreate the mona lisa. at least I have the right mix of parts haha

may I ask one more of you guys, why can you ground the i/o jacks of a rangemaster to the negative rail and it will still work ? what the heck is going on there ? I cant wrap my brain around that one either !

I will now always ground on my bypass switch , I grounded on the board instead not knowing.

the Rm working no matter how I ground it