universal power supply

Universal Power Supply Circuit

This universal power supply contains, beside the bridge rectifier, a voltage stabilizer (78xx) and a pnp power transistor. This combination allow a load current up to 5 A. As you know a voltage stabilizer in a TO-220 package can deliver up to 1A. The additional power transistor takes the load current of about 200mA.

The transformer voltage must be greater with 4V than DC stabilized voltage. C1 is calculated for 1A/1000uF, so at 5A C1 must have 4700uF. Both, transistor and voltage stabilizer must be mounted on a heatsink.

Universal power supply circuit diagram

universal power supply


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    The capacitor value I have seen is 10,000 micro farad the more the smoother. and the 12 volt regulator can be substituted without mods

  • Willail974

    Hi M. Marian,

    Great work. Please could you give me the value of C1 for 3A current circuit? And the reference of the diodes used for the bridge?
    Can i use this circuit to decrease a output regulated voltage of 20V-3A to 12V-3A with a LM7812?
    Could you give me some advices?
    Thank you