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N Scale LED Electronics
Bill has posed this question for readers:
I have some 3 volt LED street lights that were supplied with separate resistors. How do I wire these resistors to the lights?
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Hi Bill
You will meed to solder the reststors from the positive wire of your power supply to the annode of the LED the longer lead is the annode I presume the LEDs may have a wire from each lead of the LED so with a multimeter find the red wire from the LED and the black from the LED (the black wire goes to the negative of the power supply) if the circuit is complete the multimeter neddle will go across the scale of the meter using the resistance scale and no power connected from your power supply. Each led should be connected in parallel.
The important thing for LED’s is to limit the current to only .010 to .015 amps. The resistor has to be in series with the LED. The value of the resistor depends upon the supply voltage you have. If you are using 5V, you need a 330 ohm resistor: R=E/I. (R=res, E= Voltage, I = Current) For 12V, use a 800 ohm, and so on. Remember that too much current will damage your LED, too little, and it will be very dim. . Also, you must have the correct polarity to the LED, (the flat edged side is the negative), or you will damage the LED. All this is assuming you are using a DC supply.