Tetrafuzz

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
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Vitallka
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Post by Vitallka »

Hi to all.
Maybe you, like me, have a lot of germanium pnp transistors that have a small beta (20-30)? And you don't know where to apply them? I have the same problems :)
And I thought that it is possible to apply them somewhere and found some solution. The essence of this solution is as follows: the first stage should be a silicon npn transistor to significantly amplify the signal and solve ground problems, then two stages on germanium pnp transistors, and then a silicon npn transistor repeater (again to solve ground problems) .
After some simulations and practice in reality, the following scheme was born:

And here I recorded through a tube amplifier and a dynamic microphone:
https://app.box.com/s/ujg4as6d2fdwsxdervft77qiuaireocc
https://app.box.com/s/8g0xgl5ukdfg39vdq8thacvq9rpi61cw
https://app.box.com/s/yfpl0occpcthnlg17j4ykl54sob5bbyg
In addition to MP26 transistors, which I used, you can try any other pnp germanium transistors, even with a beta that is less than 20. And capacitor C5 can be connected via a switch - the boost mode will be disabled.
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tetrafuzz.GIF

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TWSpedals
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Post by TWSpedals »

This is cool. My solution for crappy germaniums is to couple them with a silicon transistor in a szikali pair.
Have a nice day!

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Manfred
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Post by Manfred »

Great development, sounds good to me ! :thumbsup

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Vitallka
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Post by Vitallka »

As an experiment, I decided to put a 2n7000 transistor in the first stage and this is what came out of it:
https://app.box.com/s/v1avb6l3zpow55x5330naqusn5ep8ku5
https://app.box.com/s/jgsh12okdvn233bd3bfkvfi7dj8u3dbi
https://app.box.com/s/l571m0h6s8vfr87178f3n6jzqz92h9ke
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tetrafuzzY.GIF

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Ichabod_Crane
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Post by Ichabod_Crane »

What's difference you can hear with mosfet instead BJT transistor?

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Vitallka
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Post by Vitallka »

It seems to me that with 2n7000 the sound is softer and more blurred, and with bc547 the sound is slightly sharper and clearer

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Vitallka
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Post by Vitallka »

I found an error in the diagram. Resistor R18 should be 10K, not 1K

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Vitallka
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Post by Vitallka »

Made some changes to the diagram, as there was an extra hole in the case, and corrected some inaccuracies in the diagram.

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tetrafuzz v1.GIF

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