Finishing Kilimanjaro - Measuring / Biasing

[joelorigo]

I have a Kilimanjaro that I am trying transistors on. I have a "3 knob Tone Bender PNP" setup from Small Bear that I am trying. These:

Transistor Set - 3-Knob Tone Bender PNP Generic

New England's source for guitar pedals, pedal parts and electronics.

smallbear-electronics.mybigcommerce.com

Obviously I am not sure these transistors will work but I am confused about what steps to take to find out. I have the transistors inserted and now what exactly?

 

[joelorigo]

The 1M resistor is just a starting place. Your Q1 has very little leakage and Q1 in a TB Mk1 needs leakage in order to pass signal and work. Same with the Kilimanjaro circuit. The 1M resistor simulates transistor leakage for Q1.

Ok. And if it isn't sounding good start going higher and lower with the resistor values? For going higher I currently have 1.2M, 2.2M, 3.3M & 10M. For going lower (lower would be in the "k" measurements right?), the highest I currently have is 470k.

This is where breadboarding the circuit would come in handy... Build up the circuit on breadboard and that way you can test it out and modify it to your liking before committing it to the soldered PCB.

I see. I haven't ever breadboarded, but I see what you mean.

 

[joelorigo]

Yeah, what you bought from Small Bear is a set for a TB Mk3 or 3 knob TB which is a different beast. Out of that set you bought from SB, try switching Q2 & Q3 around. For Q1 use something with gain of 60-80 and leakage of 200-350ua, maybe more. You could use the Q1 from that SB set but you will have to add a resistor from Q1 collector to Q1 base, like a 1meg or so.

I tried swapping Q2 & Q3 and a 1M on Q1. Nothing really useable I can get turning the knobs and trimmer.

Question: if I get transistors that fall into your Tone Vender Observations specs, is it the case that they should work in a mkI? Or is the circuit picky enough that one might have to go through different transistors that have those specs to get it working?

 

[fig]

It's all about the gain and leakage. If those are in the target range, the pedal will have much better results.

 

[joelorigo]

I am out of my element on this one. I don't have a transistor tester, I don't have a lot of transistors. Would anyone who has the experience and transistor stock want to get it working? I'd pay you for your time.