Chuck D. Bones
Circuit Wizard
The middle knob is BIAS. Design mod details here. I reversed the BIAS pot and went with A100K.
I mixed it up with the transistors on this build...
Q1 - vintage military 2N2484. HFE = 570
Q2 - Russian MП38A blue top. HFE = 58; Iceo = 68μA
Q3 - 2N4250 (came in a transistor grab bag from EG) HFE = 387
Q4 = BS170
Here's how I hooked up the BIAS pot. Snug, but it fits.
I mixed it up with the transistors on this build...
Q1 - vintage military 2N2484. HFE = 570
Q2 - Russian MП38A blue top. HFE = 58; Iceo = 68μA
Q3 - 2N4250 (came in a transistor grab bag from EG) HFE = 387
Q4 = BS170
Here's how I hooked up the BIAS pot. Snug, but it fits.