Mosfet as voltage regulator

bertus

Joined Apr 5, 2008
22,921
Hello,

When you want to use the LM317 as regulator, you will get a max of about 10 Volts on the output as the LM317 needs some voltage to regulate.
Also the current will be limited to about 1.5 Amperes, as the LM317 can not handle more.

Bertus
 

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dl324

Joined Mar 30, 2015
18,326
I want to make a variable bench power supply with the help of a smps which output is 12volt 18amp.
Why didn't you say so in the first place?

In addition to a MOSFET, you need an inductor, capacitor, diode, and circuit to control output voltage. There are many references on the Web.
 

wayneh

Joined Sep 9, 2010
18,102
18amps current for a bench power supply is a bit of an overkill!!!
Agreed. The first project many of us do on the bench is to make an LM317 circuit to control voltage to our breadboard. Most projects don't need more than 100mA or so, and the capabilities of the LM317 are more than adequate for this. It might even be thought of as a protective device for the breadboard, since the LM317 is not going to pass enough current to seriously damage everything.

Don't move to higher power supplies until you're in control and understand the risks.
 

Thread Starter

Avijit Palit

Joined Jul 19, 2017
81
Agreed. The first project many of us do on the bench is to make an LM317 circuit to control voltage to our breadboard. Most projects don't need more than 100mA or so, and the capabilities of the LM317 are more than adequate for this. It might even be thought of as a protective device for the breadboard, since the LM317 is not going to pass enough current to seriously damage everything.

Don't move to higher power supplies until you're in control and understand the risks.
I know that 18 amps is very high and dangerous. Then, is there any option to control to limit current without droping voltage.
 

Thread Starter

Avijit Palit

Joined Jul 19, 2017
81
There is a convention of measurement that everyone measure electronics components as voltage that is 3 volt led or 12 volt motor etc. But current is another unit to considered to be measured. For example, a 12 volt motor can not run on smps (output 12 volt, 18 amps). Sorry for stupid english.
 

GopherT

Joined Nov 23, 2012
8,009
There is a convention of measurement that everyone measure electronics components as voltage that is 3 volt led or 12 volt motor etc. But current is another unit to considered to be measured. For example, a 12 volt motor can not run on smps (output 12 volt, 18 amps). Sorry for stupid english.
What is the goal of your bench power supply? I electronics, motors, heater, LED lighting? Also, what is the rating of your LEDs, motor, or what every you plan to do with it.

Note that your request for 12V 20A (240 watts) needs 240W from an AC wall socket.
 

Thread Starter

Avijit Palit

Joined Jul 19, 2017
81
What is the goal of your bench power supply? I electronics, motors, heater, LED lighting? Also, what is the rating of your LEDs, motor, or what every you plan to do with it.

Note that your request for 12V 20A (240 watts) needs 240W from an AC wall socket.
What should be the standard amount of current for 12 volt output source?
 

dendad

Joined Feb 20, 2016
4,637
Some of your comments and questions make no real sense. I suggest you read up on some basic electronic theory and get to understand that first. There have been some good reference sites shown to you on other threads if I remember rightly and it would help you a great deal to follow them up. Then if you get stuck, you can ask real questions with meaning.
 
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