home about contact circuits links tools




12V Regulated DC Power Supply

12V regulated dc power supply circuit


Step-down transformer 12V
Bridge rectifier (DF02M) or 4 1N4001 diodes
2200µF, 35V capacitor
100nF ceramic capacitor
10µF, 35V capacitor

lm7812 pin configuration
lm7812 pin configuration

In this circuit, transformer of 12V secondary voltage is used. With the filter capacitor of 2200µF, the voltage entering the voltage regulator IC is approximately equals to peak voltage of the wave form minus 1.4; where 1.4 is the p-n junction voltage drop across two diodes as each half cycle passes through two diodes. That is

Vpeak - 1.4 = (Vrms x √2) - 1.4

(12 x √2) - 1.4 = 15.6

hence filtered DC voltage applied to the input of LM7812 is 15.6V.

If you need output voltage of 5V, 6V, 8V, 9V and so on, you will only change your transformer to the one with secondary voltage relative to what you want. Replace your voltage regulators with LM7805, LM7806, LM7808, LM7809... accordingly. Also note that the capacitor must be replaced with the one that has voltage greater than the peak voltage.

Related pages

Power supply
Dual DC power supply
12V regulated DC power supply

0-35V variable DC power supply
Transformerless DC power supply


The contents of this site are base on wide consultations, practical background and experience. 100% accuracy of the contents is not promised, so your contributions and suggestions are highly welcome by the author. This site will be updated from time to time, so remember to check back occasionally for updates. Send your contribution here.

free counters
Copyright © 2013 by Awotol. All rights reserved.
You are free to link to any of the pages on this site but direct use of any of the contents on your site is prohibited