Hi Guys,

I am a beginner. Can you help me, how to make a DIY Power Supply? I have a 12v AC adapter, I want to make it into a variable DC power supply from 0-12v. How much ohms of Potentiometer I need to make it? and also using a digital voltmeter to read how much is the variable output voltage.

 

First you will need a bridge rectifier and a smoothing capacitor to convert the AC input to a smooth(ish) DC voltage. That voltage will be around 15V which leaves 3V for the regulator overhead which is do-able.
Then you will need an adjustable regulator of some sort - you can't just use a pot.
There are some simple regulators which will adjust down to 1.2V. If you insist on it going down to zero volts it gets more complicated.

How much current can your AC adaptor supply?

 

First you will need a bridge rectifier and a smoothing capacitor to convert the AC input to a smooth(ish) DC voltage. That voltage will be around 15V which leaves 3V for the regulator overhead which is do-able.
Then you will need an adjustable regulator of some sort - you can't just use a pot.
There are some simple regulators which will adjust down to 1.2V. If you insist on it going down to zero volts it gets more complicated.

How much current can your AC adaptor supply?

It can supply 3 Amps. I am sorry, I mean I have a 12v dc adapter, my bad

 

Hello,

If the adapter is 12 Volts DC, you can go from 1.2 to 9 volts using a LM317 for 1 Amp or LM338 for more amps.
With a LT1085 , you can get upto 11 volts on the output.

Bertus

 

OK, a regulator needs some voltage to work with so you can't get 12V out from 12V in unless you use a switch mode method which is a lot more complicated than the @bertus method in post #4.

 

Hello,

If the adapter is 12 Volts DC, you can go from 1.2 to 9 volts using a LM317 for 1 Amp or LM338 for more amps.
With a LT1085 , you can get upto 11 volts on the output.

Bertus

yes, that's why I ask questions, to overcome stupidity hahaha. But Thank you very much. Much appreciated.

 

OK, a regulator needs some voltage to work with so you can't get 12V out from 12V in unless you use a switch mode method which is a lot more complicated than the @bertus method in post #4.

Okay thank you very much. I will search on that switch on method. Have a nice day.