DIY bench power supply

[chatziva]

I recently got 2 of these puppies from another member in unused condition.

Apparently they are 24V 6A rated SMPS from Meanwell.

They look really good quality with Rubycon caps, good protection etc. so it looks the business.

I would like to build a bench power supply with those.

I am looking for adjustable voltage up to +/- 20v @ 5a max.

Any good schematics out there?

 

[chatziva]

Would that suffice?

 

[chatziva]

I have simulated with the LT1086 and it's looking good.

 

[chatziva]

...and with realistic parts...

any comments?

 

[prasimix]

Keep in mind that you'll need a huge heatsink if you don't want to put something between Meanwell and sketched regulator. In theory up to 100W per rail.

 

[chatziva]

Indeed a big heatsink is needed. I just realised that LT1083 is capable of 7.5A so I might just use those. Not on digikey or mouser though hmmm...

 

[rikkitikkitavi]

You wont be able to lose 24V @ 5A through a single LT108X.

You will need to spread the heat loss through several pass transistors, or parallelled regulator IC. For the later there is a lot on the net. Might even be some examples for the LT108X ICs. They are expensive though...

For the former, look for schematics aswell. Most powers upply schematics deal with rectified AC input and a large cap, you have a good DC voltage (albeit with some HF ripple and noise)

Prasimix has a huge thread about his 50V 3A adjustable supply. there is a good layout for the regulator part.

 

[janurmas]

How about this:

 

[chatziva]

It's nice but a bit too complicated for me.

I think I will do a pair of bipolar channels with direct output from the SMPS up to 5A, and then add a couple of adjustable bipolar channels up to 1A.

 

[gmphadte]

Since the output voltage of the SMPS is 24V regulated, you don't need a regulator. One pass transistor and a potentiometer should be fine. Current limit can also be realized, if needed, with few components.

Gajanan Phadte

 

[infinia]

It's nice but a bit too complicated for me.

I think I will do a pair of bipolar channels with direct output from the SMPS up to 5A, and then add a couple of adjustable bipolar channels up to 1A.

good projects for learning electronics AND useful for bench testing other stuff later.

just a note for ya > the 2 resistor string R1, P1 controls the voltage, so the actual connection should be near the panel jacks (use smaller wires) for precise control at higher current draws.

 

[chatziva]

Good point infinia, thanks!