R1 = 0.56 Ohm, 1 Watt, wire-wound type, 5%
R2 = 750 Ohm, 5%
R3 = 2K7 (2700 ohm)
P1 = potentiometer, 1K, Linear
C1 = 2200uF, 35V
C2 = 470pF
T1 = 115/10 VAC transformer. Center Tap (ct) not needed.
IC1 = uA723, LM723, or equivalent.
Q1 = 2N3055, NTE130, or substitute. (TO-3 case) Mount on a coolrib!
BR1 = 80V-5A (or better)
- C1 filters the noise and spikes off the AC. Adjust the circuit for 9V or 12V output voltage, or whatever voltage level your pc mini drill is using, with the P1 potentiometer.
- Q1 can also be a MJ2955 in a TO-3 case.
Design by Tony van Roon
Watch the video: