Isolating slug on blue LS?

ResQTech

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NJ, USA
I want to mount some blue luxeons in my car. The body of the car is negative (grounded). So, does the slug on a blue Luxeon needs to be isolated from the heat sink? If so, how do you do that?
 

Zelandeth

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If memory serves me correctly, the slug is connected to the cathode (negative) side of the LED. (It's positive in the red/amber ones).

Strictly speaking, no, you wouldn't need to isolate them. However, I have no idea if in the long term not doing so would be harmful to the LED - and I'm not in a position to find out. So if I were you, I'd isolate them anyway.

Isolating the slug is pretty simple, just use some form of thermal epoxy which isn't electrically conductive. I believe some people have had success with the use of "Sharpie" markers as an electrically isolating coating as well, without compromising thermal conductivity.

No doubt, others will be able to answer your question a lot more thourghly though!
 

tvodrd

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You will only need to isolate the slugs if any of the emitters are in series. If they share a common ground, should be no problem. They will require a suitable down convertor. Just using resistors could be iffy due to the voltage fluxuations.

Larry
 
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