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I plan on putting 2 3w led's in series and use your diagram. With that, I still only need the 1w 2 ohm resistor, correct???
Craig
Thanks, but what about my plan to mount these led's to a pcb? Will there be any
problems there (I know I am going to have to get a heatsink for them anyway)?????
When cutting, drilling, tapping aluminum, Alcohol works great, gives good clean cuts and doesn't gall. I use denatured alcohol all the time, not sure about rubbing or isopropyl alcohol.They DO get hot (very hot), so you WILL need to mount them on a generous heat sink, mounting them on a PCB will not be sufficient, they will suffer thermal breakdown.
If you have a piece of 3/16 aluminum big enough to act as a mounting plate for your application, you can drill and tap it to accept the M3 screws (make sure you use a fiber insulative washer!) to secure it to the plate, which will be your heat sink. A couple of drops of thermal paste will do you good. You will need a metric tap set, cheap enough at Harbor Freight, or your local hardware store (I hope!).
40 Piece Metric Carbon Steel Tap and Die Set
That one is carbon steel, so something soft like aluminum or copper should yield no problems with it. Mild steel and the like, you will need to go slow and easy and use cutting fluid/oil.
HTH,
Andrew
Since your using 3 watt LEDs, My thoughts are that you will run them dimly for you tail lites and then go full on for the brake lites, full bright would be the 2 ohm, the tail lites will have a higher value that will get shorted out by the brake or turn signal. not sure how you're gonna handle the turn signals, maybe use a relay to short the resistor for the tail light when brake light and or signal is supposed to be on.------?????????Thanks, but what about my plan to mount these led's to a pcb? Will there be any
problems there (I know I am going to have to get a heatsink for them anyway)?????
Also, what you were saying is that instead of a 2 ohms resistor I would need close
to a 4 ohms resistor?
Craig
Quick question on the metal for the heatsink. Is what you suggested thick enough to put
2 led's on it??