Dear Shahzad,

OK the base circuit is given by you. But any power supply circuit is incomplete in the absence of the connected load details that it is expected to support.

If you can tolerate unregulated 12V directly from the adaptor then proceed as below.

1. Tap of 12V directly without any regulator.

2. Use a 7809 preregulator instaed of the 7812 that you are now using and throw all those diodes / 1K stuff.

3. Connect a 10MFD/25V tantalum capacitor at the outputs of the 7809 and 7805 .

4. Use a good heat sink meant for the regulator package that you are using.


Thats it. This way both regulators will just see a differential of about 3 to 4 Volts and that is fine for a start. This drop multiplied by the load will give you the power dissipation - just cross check that to be sure. That is home work.

Raghu