# Leakage voltage in relay mecanical

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

1. ### bravehamid

27
0
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

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2. ### Harald KappModeratorModerator

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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

27
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Dec 10, 2014
My relay is 5 volts.
Yes, when I open the lamp, there is a voltage

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4. ### kellys_eye

4,276
1,146
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 KappModeratorModerator

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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

27
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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 KappModeratorModerator

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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

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

4,276
1,146
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

27
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Dec 10, 2014
But my schematic is the same.
Be careful when the lamp is opened, there is also a voltage of 16 volts.

11. ### Harald KappModeratorModerator

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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

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

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13. ### Harald KappModeratorModerator

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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

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

15. ### bravehamid

27
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Dec 10, 2014
What kind of section do you think of?

16. ### WHONOES

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

17. ### 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 KappModeratorModerator

10,069
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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

11
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. ### davennModerator

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