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cc cv 723 psu

m3vuv

New Member
hi all im trying to build a high power bench psu, 1volt to 30 would be good,thats the easy part,now the hard bit,im after adjustable constant current on the output,also adjustable say 100ma to 25a,i have all the hardware bridge transfo etc,heres what ive got 5x lm723 10x 2n3773 1x 100amp bridge rectifier 1x 400va 30v transformer,with multiple taps 1x lm334z and various op amps also 1x sg3532 reg and 4x lm393,any ideas on a schematic?,cheers m3vuv.
 

MikeMl

Well-Known Member
Most Helpful Member
Have you got a huge heatsink and maybe a fan? You gonna need them...

Say V(unreg) = 35V. At V(out) = 1V @ 25A, the brute force power dissipation in the regulator is (35-1)V*25A=850W.

You might have to think about switching taps on the transformer, or a switching pre-regulator to reduce the input to the pass transistors down to about 2V above the final V(out).
 
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m3vuv

New Member
that was my thoughts exactly,i was thinking of switching a couple of relays to change taps,just a high and low range,i have huge heatsincs fane etc,just need a decent schematic,current limiting is easy on the sg ic and 723,cc is something i having trouble with!,regards m3vuv.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I think I have a Harrison Labs 812C. I need to check my schematic. The bay has one and a manual. It's like 36V @ 10 A.

I bought a broken one for like $15.00 USD in the 80's. It' basically a lot of transistors in parallel, a fan and selectable taps.

The deal with this is it;s a "Fixed voltage power supply, selectable between 0 and 32 V"
There are two post that set the minimum voltage, and max voltage (top accessible). Then you set the taps.
A screwdriver adjust on the front selects between the two voltages.

A direct short will result on 10 A at nearly 0V.

It's a totally discrete design with overload protection, not really current limiting.

EDIT: Fixed stuff I verified.
 
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