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Old 12-13-2007, 10:53 PM #1
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Default Can I use an LED as a resistor?

Not sure if this will work, but I thought I'd ask here I am planning on getting a heatsink made for my Kentorch that I am making. It will have fins cut out of it. Can I use an LED instead of a resistor so that I can have some funky light coming from the spaces in the heat sink?

Cheers,
Ray ;D


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Old 12-13-2007, 11:20 PM #2
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Default Re: Can I use an LED as a resistor?

As long as its the right value resistance. Keep in mind that, just like laser diode, not all LEDs offer the same resistance, and resistance changes with voltage (take that Ohm!) as well as temperature.
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Old 12-14-2007, 01:21 PM #3
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Default Re: Can I use an LED as a resistor?

What I have found is that at any decent current, the LEDs burn up in about 2 seconds.
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Old 12-14-2007, 01:43 PM #4
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Default Re: Can I use an LED as a resistor?

That's because if the LED's in series with your LD, you'd be asking the LED to run at the same current as your LD, like 200mA. You'd need either an LED out of a 1W or higher flashlight, or several "normal" LEDs in parallel. I'm not if that would screw up the current regulation to your LD or not.
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Old 12-15-2007, 05:16 PM #5
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Default Re: Can I use an LED as a resistor?

It won't screw the current regulation while you have the LED's connected in series with the LD, even if the LED's themselves are connected in parallel with each others.

However the circuit can fail if you connect too much leds in the circuit and your driver cant supply enough voltage to keep the current regulated.

but if you conect just a normal led you will fry it ;D

EDIT: just dont mess with leds on the ---[resistor]----[pot]---- part of the circuit, since led's dont have a fixed resistance value it will cause unexpected behavior on the current regulation and likelly fry your LD!!
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Old 12-15-2007, 05:34 PM #6
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Default Re: Can I use an LED as a resistor?

Err, no.
LED = Light Emitting Diode, the whole point of a diode is that it has very low resistance in the forwards bias.
If you want to incorporate some LED's, I'd set up a parallel connection between the switch and the remaining terminal. Then I'd put an LED and a suitable resistor within the parallel circuit.
(Really depends on your set-up though, dont go putting an LED in parallel with a 9v battery )

Basically, if you want some LED's, take power from your driver board and then protect the LED seperatley.
You could use it in place of the (1N4001?)diode if you found a .3A LED.
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