Hi there,

About this kit

The description is here

https://moodysounds.com/wp-content/uploads/2017/11/Bone-Bender-1-description-and-working-theory-text-.pdf

Now there are of course questions:

Can the germanium transistors be substituted and if so with what recommended partnumbers?

Answer: yes any NPN germanium transistor with enough gain ( say hfe 70 and upwards.)

Question 

If I have two transistors with different hfe, one higher and one lower which one comes first and which one last?

Answer:

This is a sound preference and chances are there would be minimal difference and the curious can mount sockets and decide.

There are ofcourse something like 40 times as many PNP germanium transistors made so we will be looking at projects to come for those.

For those starting with tubes NPN transistors were just slightly easier to get a grip on 😉 but PNP was the first... so we'll have a look at transistor history later aswell.

I can see what I can do making a list of older NPN types 

What about leakage current?

Answer

Leakage current can be modeled as resistans between collector and base and actually in many older circuits leakage cuurent is calculated with and

and you may see a circuit that would not work without leakage such as the buffer used in FZ-1. It does work because leakage current provides a voltage enough to bias the transistor. We'll have a closer look at this in a coming pdf

So now in the Bone Bender 1 circuit there is a bias network that set linear operation in a wide range of leakage from very little to quite a bit.

Have great fun

BJ