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led help????

ok im a noob when it comes to leds and electricity, but i was told someone heremight could help with my delima.

what im trying to do:
drill holes into tail light on my ninja and put yellow leds in the hole and wire them to the existing blinker wires.

the problem:
messured the voltage coming off of the wire and it pulses from 0vdc to 7.22 vdc
i have been looking on ebay at prewired 12v leds but dont know what im needing.
any help wouldbe greatly appreciated!!!!!!!


andy707076 years ago
7.22V is a strange voltage, chances are, it's 9v and it is nearly dead, or if you measured the pulse using a multimeter, it's refresh rate is slower than the pulse and you got it on the up/down ramp (assuming it's not a square wave, which it should be). Try finding the power source by tracing the wires back, take note if it passes through any components on the way as these will affect resistance. When you do find the nominal voltage, you can use an online resistor calculator to calculate the value you need. Chances are it isn't going to round to a good value, but as long as it is within about 50 ohms of the resistor you have, it should be fine. If the calculator asks you for the current of the LED, assume it is 25ma (unless you have high brightness LEDs), and te voltage is usually about 2v-3v (2v for dim colours like red and yellow, 3v for bright colours like blue and white, but it is best to check the voltage and current of your LEDs. I have seen them range from 1.8-3.3v, and 10mA to about 60).
rickharris6 years ago

This
is a fairly magic site for LED knowledge 
Any LED can be used, as long a resistor is used to reduce the voltage to an appropriate level. There are a number of online calculators that will tell you what resistor you will need for a certain LED.