Leds on PSU.

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Just add a resistor in series with the LED and connect them between a rail and GND or between rails, like in the image below.
An externally hosted image should be here but it was not working when we last tested it.


The resistor value is calculated as follows:
R = (U-1.5)/I
R in kohms
U is the voltage over resistor and LED, in volts
1.5 is the voltage drop over the LED (this value varies, depending on the color of the LED)
I is the current through the LED, in milliampers
Example: For 30V rail and 5mA the value of the resistor is 5k7. The closest standard resistor value is 5k6.
 
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