Need help in LED lighting

[Ebi_90]

HI,
I have connected a 48v 1.2amps dc supply to a 48 volt motor.I need a led to indicate that the motor is running.So i connected a BLue LED with a 50k resistor in series.I connected the LED,parallel to the motor.When the power is switched on the motor runs and the LED glows but when i switch it off and on the LED does not glow.

Can anyone sugsest a solution and also correct resistor value to be put for LED at 48v 1.2amps.Should i put the resistor in series or parallel?
Thankyou

 

[KJ6EAD]

LEDs have low reverse breakdown voltages and motors throw big reverse voltage spikes on the line when they're switched off and their magnetic field collapses. Get a new LED and put a power diode such as a 1N4007 in reverse parallel with the LED/resistor combination. This will snub the reverse voltage spike.

The current limiting resistor should be in series with the LED and should be ~2.4k - 3.3k.

 

[foTONICS]

+1 KJ6EAD

 

[foTONICS]

put the LED under a loop and look for a small brown/black spot on the diode in the centre of the LED

 

[Ebi_90]

Thank u sir