Component Parts List:
T1 = primary 115[220]/secondary 8 VAC transformer. Center Tap not needed.
Q1 = 2N1613, NTE128, or substitute. (TO-39 case) On coolrib!
BR1 = 40V, 4A. (Check max current of your mini-drill and add 2A)
R1 = 470 ohm, 5%
R2 = 1K, 5%
P1 = potentiometer, 10K
C1 = 1000uF, 25V

Notes:

• C1 filters the noise and spikes off the AC. If you find the circuit output too noisy add another electrolytic capacitor over the output terminals. Value can be between 10 and 100uF/25V.
• The output voltage is variable with the 10K-potentiometer.
• The transformer input voltage refer to your home power source.
• Mount the transistor on heatsink / cooling rib to prevent overheating.

Circuit design by Tony van Roon

The post 6-12V Variable Regulated Power Supply appeared first on Circuit Schematic Diagram.

This is high quality 0-30v stabilized variable power supply circuit diagram. You will able to adjust the output voltage from 0 volt up to 30 volt DC. You also able to adjust the current output value from 0.002 A to 3 A. This variable power supply incorporates an electronic output current limiter that effectively controls the output current from a few mA (2 mA) to the maximum output of 3 A that the circuit can produce.

Component list:

R1 = 2,2 KOhm 1W
R2 = 82 Ohm 1/4W
R3 = 220 Ohm 1/4W
R4 = 4,7 KOhm 1/4W
R5, R6, R13, R20, R21 = 10 KOhm 1/4W
R7 = 0,47 Ohm 5W
R8, R11 = 27 KOhm 1/4W
R9, R19 = 2,2 KOhm 1/4W
R10 = 270 KOhm 1/4W
R12, R18 = 56KOhm 1/4W
R14 = 1,5 KOhm 1/4W
R15, R16 = 1 KOhm 1/4W
R17 = 33 Ohm 1/4W
R22 = 3,9 KOhm 1/4W
RV1 = 100K trimmer
P1, P2 = 10KOhm linear pontesiometer
C1 = 3300 uF/50V electrolytic
C2, C3 = 47uF/50V electrolytic
C4 = 100nF polyester
C5 = 200nF polyester
C6 = 100pF ceramic
C7 = 10uF/50V electrolytic
C8 = 330pF ceramic
C9 = 100pF ceramic
D1, D2, D3, D4 = 1N5402,3,4 diode 2A – RAX GI837U
D5, D6 = 1N4148
D7, D8 = 5,6V Zener
D9, D10 = 1N4148
D11 = 1N4001 diode 1A
Q1 = BC548, NPN transistor or BC547
Q2 = 2N2219 NPN transistor
Q3 = BC557, PNP transistor or BC327
Q4 = 2N3055 NPN power transistor
U1, U2, U3 = TL081, operational amplifier
D12 = LED diode

Detail explanation 0-30V stabilized variable power supply circuit, visit this page

The post 0-30V Stabilized Variable Power Supply with Current Control appeared first on Circuit Schematic Diagram.