small neon lights for reverse polarity indication

Discussion in 'General Electronics Chat' started by sdowney717, Jan 15, 2015.

  1. sdowney717

    Thread Starter Member

    Jul 18, 2012
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    I have these 2 lights came out of my Princess stove that is on the boat.
    I replaced all 4 on the stove with new lights.
    I want to use these 2 for reverse polarity hookup, they would light up if hot and neutral wire reversed
    MDUSTRIAL DEVICE
    2170A23 SR is printed on them
    [​IMG] .
    I recall a resistor was in series with the neon light.

    I do have a working one, but I need to measure the resistor.
    Does any one know what the value would be so I can test these here at the house?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Depends on the neon, but 100K to 220K is likely ok.
     
  3. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
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    less for 110v
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
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  5. takao21203

    Distinguished Member

    Apr 28, 2012
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    yes but its not neccessarily a NE-2

    Some lamps are designed for higher currents or just will be very dim behind the plastic.
    Low currents prolong the lifetime however.
     
  6. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
    13
    55K ohms seems to work well.
    These only light if you plug in backwards the polarity, so 99.99% they will never be on.
    Not dim, not too bright, just looking right.
     
  7. takao21203

    Distinguished Member

    Apr 28, 2012
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    good one. but true, no need to worry about wearing out.

    I'm now importing blue one's from China already have green ones, with phosphor coating.
     
  8. sdowney717

    Thread Starter Member

    Jul 18, 2012
    385
    13
    This stove is a 1970 model, so they are 45 years old.

    The 55K resistors are about 1/4 inch wide and inch long so I think big enough to work. They came out of an 3000 watt inverter.
     
  9. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    It really depends on the neon design current - you probably won't see many higher than 10mA, 4mA is more like it although I've seen neons rated as low as 0.4mA.

    Haven't tried lately, but the resistors in those live test neon screwdrivers were higher than the meter I had at the time could measure.

    AFAICR: the highest colour coded resistor I've seen in a neon lamp assembly was 470k.
     
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