TwoToneFuzz help

T

Toastman

New member
Hello, I recently built the TwoToneFuzz it works but there are some problems...

Well on the MK2 setting there is this high pitch squell, I have to lower the impede and gain to make it somewhat bearable. It is coming from the pedal, the guitar volume doesn't effect it.
On the MK1,5 it is there too, just barely hearable.
(Will add photo and vid soon)

I think it is something transistor related I tried adding the 47/100pF cap between the legs, didn't help.

And the other problem, I used germanium transistors. Well the Q2 only work with one from my batch of about 10. Otherwise it is always gated and the bias works two ways. All transistors work fine in Q1 and Q3 even in my treble booster circuit. Don't know the exact type and values:(

I tired measuring the voltage at Collector and it all seems normal.

Also the ON/ON switch is slightly buggy, I need to change it, I have to click it twice into position. But this shouldn't be the cause if I am not mistaken.

Thanks for any help, tips with trouble shooting:))
 
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My first thought with squealing complains is, has this circuit a charge pump? What charge pump and what happens with another IC and what happens without the IC in the circuit?
 
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I tried capturing it on video, but it isn't noticeable there.
It's like a high pitch squell at the end of notes, I think it could be oscilation from the transistors.
 
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Toastman said:
I tried capturing it on video, but it isn't noticeable there.
It's like a high pitch squell at the end of notes, I think it could be oscilation from the transistors.
Click to expand...
Confirm also that the charge pump IC has an 'S' in the label, as in TC1044SCPA. The ones without the 'S' emit a 10kHz noise and are basically unusable for audio applications. If the squeal is not continuous (as you imply, only at the end of notes), then that eliminates that specific problem.
FWIW I've found circuits tend to squeal when not properly grounded. So it's odd that this goes away when out of the enclosure.

Does the squeal change when you adjust the bias knob? This is not a circuit I'm personally familiar with, but Germaniums can also be temperature-sensitive, which in turn affects the bias and so on.
 
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It has TC1044S written on it, so that should be alright.
Put it back into the enclosure, the high pitch noise is there all the time, but it slightly changes with the bias.

It's really really high pitch, barely heareble. I cannot capture it on phone
 
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