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aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
·Frontier Communi..
reply to mackey

Re: 12V LED lights

I know I can buy LEDs and I can even string them together, but that's not what I want to do for several reasons, one of them being that high power, high efficiency LEDs are usually SM, and they require a heatsink. I want something pre-made that I can just connect to either an automotive or to some other connector/socket.

My question about resistors is whether they use resistors to limit current (lower efficiency) or an electronic regulator (higher efficiency) to limit current.
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alphageek911

join:2007-08-10
Fresno, CA
said by aurgathor:

My question about resistors is whether they use resistors to limit current (lower efficiency) or an electronic regulator (higher efficiency) to limit current.

Most 12V LED assemblies (and 120VAC LED devices), use a DC-DC switching converter, not resistors. They are reasonably efficient, often in the 90% range. Here's one example of a driver IC- »www.linear.com/product/LTC3454


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
Reviews:
·Frontier Communi..
I do know that with 120 VAC devices, unless they use something like 30+ LEDs in series, they must use an electronic regulator or be horribly inefficient; however, with 12 VDC, they could use 3 - 4 LEDs in series and a small resistor.
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alphageek911

join:2007-08-10
Fresno, CA
said by aurgathor:

With 12 VDC, they could use 3 - 4 LEDs in series and a small resistor.

They could; I've never seen that in a commercial product, though.

I have some very cheap offshore import MR16 LED lamps, and even they have switching regulators in them. I can get IC LED driver boards from China for less than 50 cents each, even in small quantities, so cost isn't really that much of an issue.


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

1 edit
Good to hear that. So I guess I can assume that unless proven otherwise, 12V LED lamps will be using switching regulators.
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alphageek911

join:2007-08-10
Fresno, CA
said by aurgathor:

Good to hear that. So I guess I can assume that unless proven otherwise, 12V LED lamps will be using switching regulators.

All I've come across have, at least. Another choice if you need brighter lights could be automotive HID lights, they are nearly as efficient as LED, and are available in higher wattage configuration (35 and 55 Watt are common), at a reasonable cost.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
Click for full size
said by alphageek911:

said by aurgathor:

So I guess I can assume that unless proven otherwise, 12V LED lamps will be using switching regulators.

All I've come across have, at least.

Yes.

Modern 12V LED lamp assemblies accept "nominal" 12V which varies based on battery status in a car or AC voltage in a home. A tiny driver board is hidden inside the base of larger lamps. Above is an MR16 lamp.

Very small automotive lamps often use a single LED and a surface mount driver IC on same board.