Voltage regulation means to prevent the voltage from dropping below or rising above a specific value. A 12-volt regulator circuit will provide exactly 12V under load or without load. On the other hand, an un-regulated 12V power supply output voltage will drop under load and rise when there is no load present.
For example, an unregulated 12V 1A power supply can output 14+V when not under load and can drop the voltage to 11V at 1.2A load and 10V at around 1.5A load. This rise and drop of voltage in un-regulated power supplies can sometimes burn sensitive electronic pieces of equipment.
A few days ago, I needed a regulated power supply so I went to the market to buy it. I was surprised to see the price tags so I decided to build a power supply myself.
Here is the power supply circuit diagram which I designed. You can download it for offline use or print this entire page to assist you while building this circuit.
Here goes the parts list.
7812 is a very good voltage regulator integrated circuit (IC). It is cheap but efficient, that is why I selected it for this regulator circuit. 7812 Pin2 connections are also explained in my regulator circuit diagram. You can see that Pin 1 is input, Pin 2 is Ground (which is often –V) and Pin 3 is output. It is very simple to understand 7812. The 220uF 25V capacitor is used as a buffer to cover the frequency gap. The second capacitor is used as an extra filter. IN4001 rectifiers are used to convert AC into DC. A transformer is used to convert 240V AC into 15V AC. If you have 110V mains then you can use a 110V AC to 15 AC transformer.
I have successfully used this voltage regulator circuit to power up my ADSL modem. My ADSL modem had a habit to restart after every few hours but since I have switched to my homemade regulated power supply, my modem never restarted by itself.
Any electronic device which requires 12V 1A power can be powered by this circuit so feel free to use it. You can post your questions and comments in the comments section below.