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Author Topic: led's using a 12 v supply  (Read 1264 times)

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Offline spike47Topic starter

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led's using a 12 v supply
« on: October 18, 2015, 03:50:26 pm »
how do I work out  what resister to use to be able to light  14 led's , using my PC's power supply of  12 volts .

cheers

spike
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Offline jeroen79

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Re: led's using a 12 v supply
« Reply #1 on: October 18, 2015, 04:18:08 pm »
Determine the LEDs forward voltage and current required for the desired brightness.
Calculate how often that voltage goes in 12V.
That is how many you can put in series.
The remaining voltage goes over the resistor.
Use Ohm's law to calculate the value of the resistor from a knowm voltage and current.

Or use: http://led.linear1.org/led.wiz
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Offline German_EE

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Re: led's using a 12 v supply
« Reply #2 on: October 18, 2015, 06:35:38 pm »
(Supply Voltage - (Voltage drop of LED x Number of LEDs))
                         LED Current in Amps

14 LEDs in series will be a problem because even at a 2V forward voltage drop that will need a 28V supply.
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Online mariush

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Re: led's using a 12 v supply
« Reply #3 on: October 18, 2015, 06:55:55 pm »
You can split your 14 leds into smaller segments and use one resistor with each segment.

« Last Edit: October 18, 2015, 07:00:25 pm by mariush »
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