Is there a simple way to indicate that contacts are open?

Discussion in 'General Electronics Chat' started by Wobbly, Mar 26, 2014.

  1. Wobbly

    Thread Starter New Member

    Mar 26, 2014
    2
    0
    Using a neon lamp and resistor across 120 volt contacts with a load resistor in series, the neon will light when the contacts open.
    What is the maximum resistance of the load resistor?
    Please provide help calculating.
    Is there any other discrete device besides a resistor which could be used in series with the contacts and still light the neon when the contacts open?
    No relays allowed!

    No this is not homework.
    It's just a problem I was thinking about going to work yesterday.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,365
  3. Wobbly

    Thread Starter New Member

    Mar 26, 2014
    2
    0
    In my case the loose wire is often in front or the keyboard.
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,365
    It's relative. Are you behind the wheel or in front of the wheel.
     
Loading...