Has Anyone Made an All Si Three Knob TB?

[A.J.]

I was thinking of trying an all NPN Si version of the 3 Knob Tonebender incorporating some of the ideas from Fuzzcental's Axis Face - has anyone tried building one of these?  I can use Si in Q1 and Q2 anyhow, so it would just be changing Q3....haven't tried changing Germ to Si before - <newb warning> figuring I'd have to add a resistor from emiter to ground and tweak a bit from collector to base - is that right (as well as, of course, changing the caps around)?

A.J.

[Dragonfly]

And Ricky's 2 knobber...

[Baktown]

Has anyone built a Vero layout for any of these?

After laying low for a few weeks, I'm itching to get back to building.

Rick

[96ecss]

Has anyone built a Vero layout for any of these?

After laying low for a few weeks, I'm itching to get back to building.

Rick

I have a pcb layout for the Hot Silicon here http://www.aronnelson.com/gallery/main.php/v/Daves-Layouts/Hot+Silicon.gif.html

Great sounding OD/Dist pedal. I like it almost as much as my BSIAB2. It has a little more Gain and Distortion than my BSIAB2. Right now, they're both on my pedal board.

Dave

[mac]

Si 3-Knob TB:
1. Get some low gain silicons, like 2n2369A or 2n3903. hfe below 100 better. Some BDxxx power transistor have low gain if marked like BD139-10.
2. Replace the 220k at the input with 120k or so to have 4V to 4.3V at the collector of Q1 and Q2.
3. Add a 1M trimpot from Q3 base to collector. Depending on the diode you use the value of the pot. Expect 300k or so. Since silicons does not change bias with temparature the diode is useless, can be replaced with say 1M to simulate diode reverse leakage.
4. Go to 7.


Si TB MKIII:
5. Again low gain silicons.
6. Add a 820k to 1.2M from Q1 base to collector to have 8v to 8.5v.
7. Enjoy

mac

[A.J.]

Thanks All - Dragonfly's SiTB looks intersting, and I think I'll try that too - I was looking to keep as close as possible to the 3-knob circuit - thanks Mac- I'll do both and report back (it's that, or yard work, today.....)

A.J.

[Gus]

You can build Hot Si without the output buffer and tone control.  Also note the different input bias setup from the other two circuits.  There is a different.  Also no trim pots.

  Make R7 a 10K and 1K with a .01uf cap across the 1K 1K to +9vdc and take the output from the 1K 10K node  to a cap then a 100K volume pot.  Other resistor values for R7  9.1K and 1K or 8.2K and 1.8K maybe with a with a different cap across it...........

[mac]

AJ,
The mods I listed try to preserve things as close as the originals.
There is another way to bias Si in 3 knob. Since Si transistor diode drop is higher than Ge, the base of Q1 and Q2 will sit higher. Increasing the 47k to an apropiate value is another way. Or tweak the collector resistor.
Q3 NEEDS a resistor from base to collector.

mac