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Higher efficiency (high amp) 12V regulator alternative to 7812

I need a high efficiency 12V DC regulator to supply my thermoelectric modules (they're very inexpensive so I had no choice but to use them). I found that the modules are most efficient at 12V @ ~7A each. I could use many 7812s in parallel but they are too inefficient and too much energy is lost to heat. Is there any alternative? Electricity bills are going up so it'd be very good if I can find an extremely efficient step-down or step-up regulator, short of using an expensive 'gold standard' ATX PSU (which are usually upwards of 500W so the power savings don't matter).

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StephanoH11 months ago

Have you tried with the 78HXX series? The H is for High current, they take up to 5 amps, but maybe with two of them...

You want a circuit like this only using a 7812
78xx Current Regulating.bmp
Since he said “Higher efficiency (high amp) 12V regulator alternative to 7812” and since the closest to a 7 amp 12 volt regulator I can find is a 5 amp adjustable LM338 and a LM138 maybe they might want to use a fixed regulator they already have.

I think since their intended meaning is construction efficiency considering he mentioned multiple 7812 in parallel.

At 7 amps current that circuit will supply 12 volts at the necessary current with only one transistor in the circuit.

That is a stalk schematic and I did not remove the extra transistors or the second schematic in it just in case they wanted more current than 7 amps.

But since it is them asking the question, shouldn’t they decide what they want Steve?

Joe
arikyeo (author)  Josehf Murchison3 years ago
I meant more of power efficiency than construction efficiency.But the LM338 is only marginally more efficient than 7812 because there's still quite a lot lost to heat. But yeah, I'd consider that if there's no other option (Like a MAX756 + toroid is to a 7805 in terms of efficiency).
You are always going to have heat no matter what you do it is the by-product of sending 90 watts of power through a circuit and the closer to a components max the hotter it gets. Now for a number of reasons one circuit will not get as hot as another but the heat will still be there.

You can reduce how hot the components get using the circuit I posted instead of using one MJE3055 use two and you reduced the power going through the transistor by half and the heat from the transistors by half. But as long as you are using 90 watts of power you will get 90 watts of heat.

Joe
You can use a switch mode PSU, and get 95% efficiency in the conversion.....
The 756 is only 300mA, MAXIMUM.
What load have you got ? A Pc supply might be the cheapest way to get a reasonably efficient supply.
arikyeo (author)  steveastrouk3 years ago
I've thought about using ATX power supply (ie PC PSU), but the standard ones usually supply at least 450W nowadays, which is overkill. Adding to that, those '80 plus' PSUs are mostly above 600-750W, which is even more overkill. I only need at most ~85-100W of power, and don't want to waste all that extra power which I won't need.
Besides, spending that much money (>$100) for PSU totally cancels out the power savings that may arise from that compared to the linear regulators, and I'm on quite a tight budget here (which was why I got those really cheap peltier modules in the first place).
An ATX supply may well NOT supply enough 12V to run your cells. You aren't wasting power in a switcher, if you aren't using it. See if your 20 dollar PSU can supply 12V@7A.

You haven't said how much current you need yet.
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