Powering 12V Strip with 16v laptop supply possible?

fefrie

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Jan 5, 2007
Messages
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I have a typical strip of leds that you can buy from overseas that is the 5m/60W/12v variety. Pretty generic with cuttable strips every 3 leds:

http://dx.com/p/car-decorative-48w-1600lm-600-smd-3528-led-warm-white-light-strip-12v-5m-250106

And I have some old laptop power supplies sitting around. 16v 4.5a

Is it possible to drive the leds with this power source? I do know that the leds can be driven on a car power circuit, so up to 14v is ok, but is 16 a stretch?

Could I add a resistor?

Or is it not worth it at all, and better to just get a proper power source.
 

Revolvr

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Joined
Jul 20, 2013
Messages
29
I have a typical strip of leds that you can buy from overseas that is the 5m/60W/12v variety. Pretty generic with cuttable strips every 3 leds:

http://dx.com/p/car-decorative-48w-1600lm-600-smd-3528-led-warm-white-light-strip-12v-5m-250106

And I have some old laptop power supplies sitting around. 16v 4.5a

Is it possible to drive the leds with this power source? I do know that the leds can be driven on a car power circuit, so up to 14v is ok, but is 16 a stretch?

Could I add a resistor?

Or is it not worth it at all, and better to just get a proper power source.

Each of the 3 LEDs are in series with one current limiting resistor, probably 100 Ohms to give about 20mA at 12V, assuming a 3.3V drop across each resistor.

16V would up the current from 20mA to about 60mA. This probably won't fry the LEDs but it will certainly shorten their life. I suppose you could try it with a short disposable 3 LED segment, and see how long they last and how hot they get. And if you can measure the current draw. Personally I'd plan to splurge a few bucks for an overseas 12V power supply.
 

DIWdiver

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Jan 27, 2010
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2,725
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Connecticut, USA
Or you could add half a dozen diodes in series with the power supply. That would drop it about 4V. Radio Shack carries 1A and 3A varieties (1N400x and 1N540x, respectively, where x is a number from 1 to 7). Their 276-1653 is a 25-pack and is a good bargain. You can get them cheaper online, but you have to pay shipping. Oh, I see you can get them on fleabay REALLY cheap with free shipping!
 
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