Variable Power Supply Circuit 6-12V

The output voltage of this power supply circuit can be adjusted from 6 volt to 12 volt. The output voltage is regulated by Q1.

Parts List:

R1 = 470 ohm, 5%
R2 = 1K, 5%
P1 = 10K ohm Potentiometer
C1 = 1000uF/25V
T1 = 115[220]/8VAC 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)

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.
10K-potentiometer used to adjust the output voltage.
The transformer input voltage refer to your home power source.
You may change the bridge diode with four rectifier diodes.

Comments

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Power Supply Adapter

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