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Leakage voltage in relay mecanical

Discussion in 'General Electronics Discussion' started by bravehamid, Jan 24, 2018.

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  1. bravehamid

    bravehamid

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    Dec 10, 2014
    hi
    i have a problem.
    I have a mechanical relay that activates with a micro and turns a lamp off and on.
    But when the relay is off , it has 16 volts on the output
    Please guide.
     

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  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Which relay?
    16 V AC or DC?
    Is the voltage present when you remove the lamp?

    Show us a schematic.
     
  3. bravehamid

    bravehamid

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    Dec 10, 2014
    I added a schematic.
    My relay is 5 volts.
    Yes, when I open the lamp, there is a voltage
     

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  4. kellys_eye

    kellys_eye

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    Jun 25, 2010
    WHERE?

    Show the lamp. The relay is connected to a 5V supply so presumably the 16V is at the lamp?
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Sorry, We need to see the secondary side where the lamp is. And indicate the points where you measure the voltage, please.
     
  6. bravehamid

    bravehamid

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    Dec 10, 2014
    There is a 16V between the two symbols. when the relay is off.
     

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  7. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Thats completely normal.
    The Neon Lamp has a finite resistance, so has your multimeter. There will flow a small but measureable current through the Neon lamp and the multimeter which in turn gives you the indication of 16 V.
    If it weren't for the Neon lamp: A standard tungsten filament lamp would have your multimeter show 220 V due to the much lower resistance of the lamp.
     
  8. bravehamid

    bravehamid

    27
    0
    Dec 10, 2014
    NO,NO
    MY LAMP IS Fluorescent lamps.
    I even open the lamp
    AND voltage is 16 volts in Relay on both sides.(Where I did mark)
     
    Last edited: Jan 24, 2018
  9. kellys_eye

    kellys_eye

    4,276
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    Jun 25, 2010
    Same thing - your meter is just 'too sensitive'.

    Your meter will draw current THROUGH the light (of whatever kind) and cause a volt drop to be read.

    See how a comprehensive question (post #6) can give a comprehensive answer (post #7)?

    You're not alone in doing this but when you come to a forum for advice it is wise to make your case clearly and concisely in order to get the correct response. This is a vital learning technique when studying electrics/electronics (indeed any subject) so please consider this when making forum requests.
     
  10. bravehamid

    bravehamid

    27
    0
    Dec 10, 2014
    Your saying is correct.
    But my schematic is the same.
    Be careful when the lamp is opened, there is also a voltage of 16 volts.
     
  11. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    What do you mean by "lamp is open"? Typically a fluorescent lamp has a starter in parallel. This starter has a built-in capacitor which in turn is a capacitive impedance. A small current through this impedance will show as a voltage reading on your multimeter.

    You can't expect good answers when you don't show us the real circuit, can you?
     
  12. bravehamid

    bravehamid

    27
    0
    Dec 10, 2014
    Sorry for defect.
    but really This is my schematic.
    Note that when I remove the lamp, it is available at a voltage of 16 V
     

    Attached Files:

  13. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Did you remove the complete lamp including the starter? If you only remove the lamp from the lamp housing there is still the starter with its parallel capacitor.
     
  14. bravehamid

    bravehamid

    27
    0
    Dec 10, 2014
    i remove the complete lamp including the starter
     
  15. bravehamid

    bravehamid

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    Dec 10, 2014
    What kind of section do you think of?
     
  16. WHONOES

    WHONOES

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    May 20, 2017
    Indicate where you are measuring the voltage>
     
  17. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    How long are the wires from the relay to the lamp. Anything more than a few cm might very well pick up an AC voltage by induction.

    Bob
     
  18. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    See post #6. The op has indicated the points of measurement as crosses and a dotted line.
     
  19. Gumby_Kevbo

    Gumby_Kevbo

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    6
    Jan 25, 2018
    Over the years I've seen a fair amount of leakage due to flux residue on the boards. If you use old school rosin core solder, (like kester 44) it looks pretty ugly, but the residue has negligible leakage. Many of the newer fluxes leak a LOT. They are designed to be washed off alfter soldering.
     
  20. davenn

    davenn Moderator

    13,598
    1,875
    Sep 5, 2009

    this wouldn't be the problem in this case


    it's still a case of a sensitive meter measuring/responding to the stray electric field of the 220V

    The relay IS NOT faulty, It IS NOT causing the voltage you see
    I would suggest that if you took the relay out of circuit, you would still see your voltage
     
    Last edited: Jan 26, 2018
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