As an example, I have 2 x identical LEDs. I want one to show when my 5V rail is working - using ohms law I would calculate the required series resistor to be 'about' 220 ohms.

The same thing for my 12V rail I again use ohms law and calculate that the series resistor needs to be 'about' 1200 ohms.

In both cases the LEDs are identical as I am certain they will be on your boards, the difference being the value of the resistor I need to put in series with each LED to limit the current to a safe level.

#4 2 years ago

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pins4u

Pinside apprentice

Gaborone

3y 34,400 1,037

OP
Quoted from Nacman:
I understand now. Thank you. So with that said, I am going to try and replace the led and see what happens.

Note that LEDs are polarity sensitive - that is, they must be inserted the correct way around - usually they have a flat spot on the case to identify the cathode which is the lead that goes towards ground.

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