DC-DC variable voltage and current lab power supply

[bengaltiger]

Hi,

looking for simple DC-DC variable voltage and current lab power supply circuit.

variable voltage (around 3 to 12 volts) and variable current. (current limiting with LED indicator)

Also I will add digital voltmeter and ammeter module.

Regards,
BT

 

[tpetar]

What current you need ?

For my thinking will be nice to have current 5A from 1,25V to 24V.

You need good transformer.

You can use linear LM338K (my favorite) or switcher regulator LM2678T-ADJ both are 5A. Price for both in my country is about 8eur. Circuits are simple and you can find it easely on Internet.


For measuring and showing actual values on LCD you can see this link :

DIP version:
http://elfly.pl/multimetr/multimetr_en_DIP.htm

TQFP version:
http://elfly.pl/multimetr/multimetr_en.htm



(Voltage, Ampere, delivered Amper Hour, Resistance of circuit-good for batteries)


LM338K example :
http://www.circuitdiagram.org/5a-adjustable-power-supply-lm338.html

http://electroschematics.com/60/power-supply-138v-5a-with-lm338/

 

[bengaltiger]

Thanks,

I need current limiting as well (adjustable current) with LED indicator.

BT

 

[tpetar]

No prob you can use one more regulator in serie to regulate current limits.

**broken link removed**


You can also see this new example :

**broken link removed**

 

[bengaltiger]

Thanks,

I like l200 form ST , its both current and voltage regulator integrated.

Is there any alternate IC from other manufacturer?

BT

 

[tpetar]

Thanks,

I like l200 form ST , its both current and voltage regulator integrated.

Is there any alternate IC from other manufacturer?

BT

Yes, any regulator can be and current regulator. L200 is old and have smaller current. You can use it why not.

 

[bengaltiger]

still looking some simple circuits for regulated and variable voltage & current psu.

Will prefer led indication in case of current over limit.

 

[sky_123]

That circuit from tpetar (the one with the op-amp) does exactly what you want, and has LED indication too. It looks like a good circuit. If there was a simpler circuit, it would not be called a circuit, it would be called a "ready-made power supply" : )

 

[bengaltiger]

in that circuit, I didnt like the idea of supplying -5V. I like L200 IC. so considering similar functionalities with L200 or similar IC

 

[tpetar]

in that circuit, I didnt like the idea of supplying -5V. I like L200 IC. so considering similar functionalities with L200 or similar IC

Look example for -5V.

 

[bengaltiger]

thanks tpetar,

But I am looking simplest possible circuit. again some BOM for -5 v.

I have 12 V supply mostly I want 3-5v output and 100ma to 1.5a output with current overlimit indicator.

Regards,
BT

 

[tpetar]

Then you can use 78S05 its 2A or some 3,3V regulator or LM317....

I have impression that you whant to make lab PSU.

 

[sky_123]

Also, if the -5V is such a concern, you could just connect to 0V, the -5V means the supply can go all the way to 0V.
I've not tried it, but that's what it looks like.

 

[bengaltiger]

Yes I mean lab power supply. current and voltage both variable. Over limit of current, a led indicator.

two lm317 possible? I want to consider another circuit.

Please let me know if that is possible.

-BT

 

[tpetar]

But you say you want 3-5V output voltage up to 1,5A. You dont need nothing special for that.

Todays universal lab power supply should have small ripple voltage, with at leat several ampere capability on output, and voltage range from 1V to 24V, this is my thinking.


Best is to put on paper what you whant.

 

[bengaltiger]

simple.

variable voltage from 3v to 5v, any value in between ex 3.2 3.7 4.0 4.5 etc.
current 0 to 1.5 amps ; I can set any value in between.
Led indicator in case of current over limit

-BT