I need a big current regulator.

[Spasticteapot]

I need a current regulator capable of at least 8A at 12 volts. Efficiency, noise, and precision aren't a big deal, as this is for a simple electroplating project. A simple design would be a plus. Any tips?

[jackinnj]

If you want to pay the shipping I have a couple of electroplating supplies in the garage. Systron Donner "Trygon" -- will do 16-19 V, probably 55 amps. I got 'em from NASA in Alabama -- they weigh about 70# each.

[Sch3mat1c]

You can try something like this,



A buck converter is also fairly easy to put together, though 8A is a little steep for something based on, say, MC34063.

Tim

[jackinnj]

One other idea - ham radio transceiver power supplies 13.8V out and beaucoup amps --

[Spasticteapot]

Originally Posted by jackinnj

If you want to pay the shipping I have a couple of electroplating supplies in the garage. Systron Donner "Trygon" -- will do 16-19 V, probably 55 amps. I got 'em from NASA in Alabama -- they weigh about 70# each.

I wish I could afford the shipping!

[jackinnj]

i could sneak 'em on a Schneider Truck.

[Spasticteapot]

Seriously?

[dangus]

It can probably be done with one or two transistors... take a look in The Art Of Electronics. Or use that op-amp CCS circuit with a suitably large power transistor, maybe a Darlington.

An old car battery charger would be a good donor for a transformer and other bits. Maybe the voltage regulator (assuming it had one) could be altered for current limiting instead.

[h_a]

You could parallel 2x LT1083 (with common sensing, see datasheet).

Of course you would have to make sure that low dropout is kept.

Have fun, Hannes

PS: a single LT1083 goes up to 7.5A.

[gootee]

I guess there are lots of ways to do it, if you already have a big honkin' DC voltage supply.

If you wanted an actual bi-polar current source and needed to be able to control the current, or modulate it etc, you could use something like a Howland Current Pump opamp circuit, with any kind of power amplifier as a 'booster' amp, right at the opamp's output (inside the feedback loops). The booster amp could be transistor or chipamp based, for example. But I'm sure there are much simpler ways of doing it, for just a constant, single-polarity DC current.

You should be able to use the same type of idea (booster amp or high-current pass device) with other low-power current-regulator circuits. An opamp and a MOSFET (and a resistor or two) should do it. Some of National.com's and others' Application Notes probably have simple circuits for things like that. Linear.com has AN18 and AN84f, for example. Apexmicrotech.com's ANs 13 and 14 might be useful. National's AN-20, AN-31, and AN-272 might be useful, to give you some ideas. Do some searches.

So you need a big honkin' DC supply.

You could try getting one from a place like jackinnj did, by searching at Government Surplus Auctions at Government Liquidation . The FSC code (in Advanced Search, there) would be 6130. But they might be listed with the wrong code, or something. Best bet is probably to just look at everything at warehouses near you, checking the details for each lot. One used to be able to get several pallets of nice, big DC supplies, there, for the minimum bid. But I haven't followed it for "a while".

Or just slap one together from spare parts.