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LED Resisitor on Mains Circuit

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bryan

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I want to add a LED to a switch in a power supply. More or less the same as a neon indicator. I calculate the resistance to be about 5.5K for a mains voltage of approx 117 volts.

Question I have is what is the wattage of the resisitor I should use.
 

Sebi

Active Member
Since the LED voltage around 2V You can calculated with 115V/5500ohm, this is 0.02A, P=U*I, 115*0.02=2.3W, But i recommend for continous use min. 4W. Or You can use X2 type condenser about 100nF with series 100ohm.Both case need antiparalel diode with LED.
 
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