# Using 12VDC spotlight charger on LED's? Answered

I have an old rechargable spotlight that I never use, so I figured I would use it for parts.  Could I use the charger 120VAC/12VDC to power some LED's, like if I wanted to make an under the counter light?
If so, would it be better to run the LEDs parallel or in series?  I was reading an instructable on beginning LED's and saw that series will divide the 12 volts to each LED (4 LEDs at 3 volts each), and running parallel will send the entire 12 volts to each LED.  Would I use resistors even if I ran the LED's in a series?    If I ran the LED'S parallel, would the follow crude schematic be correct?

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## Comments

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You ADD the "forward" voltages of your LEDs together - so, say you have two that drop 1.2V and 1 that drops 3 v, you have a total of 2.4+3 or 5.4V in your LED string.

Take the supply voltage (ideally at least a couple of  volts more than the forward drop - so here, I'd like to see a supply of at least 7V.

Take the ideal current through the LEDS, lets say for the sake of example, 20mA and then calculate (supply volts - diode drop)/ ideal current - this gives you the series resistor you need.

( 7-5.4)/0.02 = 80 Ohms.

Steve