'Blood and Thunder' PSU..

[BrainEater]

I have finally decided to build a proper 'rough power' supply......I'm sick of not having good power for my peltier work.

The specs I am looking at : 0-24 VDC @ 26 amps.

Here's what I am doing ;

I have a powerstat variac ....1.4 kVa...(116cu)..I intend to buy a Hammond toroidal transformer to connect to this....I'll probably get the 182t24....

My thought is a basic bridge rectifier/smoothing capacitor setup.I'm not worried about any regulation ,but does anybody have any tips ?

Should I get a 30v toroid? or will the 24 v model be enough ? (don't forget the variac can do 140VAC)

Thanks for any advice.

 

[BrainEater]

Ha !

no bites eh ?

Cmon, somebodys gotta have some info....

Capacitor sizes/types ?

best bridge ?

Throw me a bone.

 

[Mohonri]

24V @ 26A is a LOT of power. A simple transformer->rectifier->capacitor bank is going to be large, expensive, inefficient, and have a nasty current profile/power factor. Honestly, I'd recommend taking a couple off-the-shelf PSUs, isolate their secondaries and tie them head-to-tail, and build a high-current DC buck converter to step down the voltage as needed.

 

[BrainEater]

I do sorta agree , but here's the thing though :

I already have the variac , the enclosure , and probably the rectifiers/capacitors.

This is essentially a bench supply.PF/efficiency/size doesnt matter (to me)...it'll be a low usage kinda thing....and I do want access to the variable AC.

200$ would get me the transformer and the volt/amp meters , so thats fine by me.
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All that being said , I want low ripple....I've got a fairly good 'box-O-beefy-caps' but I might end up just buying new capacitors....

Related to this , I've never scoped the AC output from a variac , seems to me it is probably pretty noisy ....Is post-variac filtering something I should consider ?



Thanks for the input !