Tone Bender 3-knob voltages???

[mac]

I am breadbording the TB 3-knob version using GGG schem,
http://generalguitargadgets.com/diagrams/tb3cs_sc.gif
I'm using 2SD352 NPN Ge all having hfe near 50 and leaking around 150uA. Looking at the schematic this Ge have enough leakage to bias without the use of a resistor from Q3 collector to base. Last time I played with this circuit I used 2SA52 PNP Ge leaking less than 40uA so I have to use a 470k from Q3 C to B. A silicon version won't bias without this resistor I guess. I also omitted R10 on GGG schem.
But with the 2SD352s if I use a 15k for R10 the voltage at the junction of the 18k and the 10k to Vcc is 4.5v, and at Q3 collector is 2.45V. If R10 is 10k then I have 3.8V and 1.75v. If I do not use R10 then I get 7.2V and 4.3V.

I'd like to know original voltage readings or diy'ers voltages and suggestions.



mac

[B Tremblay]

I built mine according to Stuart Castledine's schematic, but I think it shares all the same biasing resistors.

Transistor voltages (using salvaged germaniums and 9.18v battery source)

Q1: C= -3.61, B= -1.55, E= -1.45
Q2: C= -3.61, B= -1.45, E= -1.33
Q3: C= -4.29, B= -50mv, E=0

[mac]

Thanks B. Reading some of your posts about the TB 3K I guess you did not use R10.
I replaced the 220k going to Vcc with a 330k to have 4.5v at Q1&2 collector. With the 220k I get 3.8v at Q1&2 collector. It seems that the bias resistors for Q1&2 are intended for very low leakage Ge or Si.



mac