Connect with us

Need help in LED lighting

Discussion in 'LEDs and Optoelectronics' started by Ebi_90, Mar 29, 2012.

Scroll to continue with content
  1. Ebi_90

    Ebi_90

    5
    0
    Mar 29, 2012
    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
     
  2. KJ6EAD

    KJ6EAD

    1,114
    157
    Aug 13, 2011
    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.
     
    Last edited: Mar 29, 2012
  3. foTONICS

    foTONICS

    332
    9
    Sep 30, 2011
    +1 KJ6EAD
     
  4. foTONICS

    foTONICS

    332
    9
    Sep 30, 2011
    put the LED under a loop and look for a small brown/black spot on the diode in the centre of the LED
     
  5. Ebi_90

    Ebi_90

    5
    0
    Mar 29, 2012
    Thank u sir
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-