Led lights flickering when off!

[Howard Wright]

Hi All

The DVLA finally came through and I’ve been able to try my special for a short drive on the road.  I have a host of shakedown problems (carb flooding, dynamo not charging etc etc) to sort out but I’d like some help with the led lights.

With all the lights off and the engine ticking over, the led lights (head, side, brake and front indicators on the car flicker very dimly.  Turning the lights on gives a good strong light that does not appear to flicker.  I’m assuming it’s to do with high tension interference from the plugs, coil or dynamo and think the circuits need suppression, but not being an electrician I don’t know what values and where to place any capacitors.

Anybody else had this problem? And how did you solve it please?

Cheers

Howard

[GK5268]

I have diodes fitted on my tail lights to prevent odd things from happening!

[Renaud]

Hi Howard,
As an electronician I would guess it could be a capacitive effect in the lights switch, or either an "antenna" created by the wires to the leds.
The way to discriminate which would be to disconnect the wires from the switch and see if it changes the flickering. If so its the capacitive effect, if not it's the antenna one. Anyway that's just by curiosity but no cure!
To cure I would suppress it by inserting a capacitor (10 nF ceramic 100V) anywhere between each of the concerned circuits and a (good) ground. Probably best to put one on each of the leds so that the connections of the capapcitor are kept VERY short.
Hope this helps.
Renaud

[Chris KC]

The Devil's work.

[Renaud]

Yes Chris but we, electronicians, are strongly connected with Him...

[Mark McKibbin]

Hi Howard,
As an electronician I would guess it could be a capacitive effect in the lights switch, or either an "antenna" created by the wires to the leds.
The way to discriminate which would be to disconnect the wires from the switch and see if it changes the flickering. If so its the capacitive effect, if not it's the antenna one. Anyway that's just by curiosity but no cure!
To cure I would suppress it by inserting a capacitor (10 nF ceramic 100V) anywhere between each of the concerned circuits and a (good) ground. Probably best to put one on each of the leds so that the connections of the capapcitor are kept VERY short.
Hope this helps.
Renaud

I have hidden an LED in the oil button (as I have a gauge) that works as a telltale for the indicator, it has been flashing when it's not supposed to and I was thinking of putting a resistor across it but a cap is a better idea, Thanks Renaud.

[spannerman]

Had same problem on my special!
Stripped lighting switch and washed out
All the years of muck and as been ok
Ever since. Think the muck was conducive
To a point ?

[Howard Wright]

Thanks everyone 

Much to take in.  As all the leds; side and head  lights, indicators (on a separate switch) and brake (again on a separate switch) are flickering And I’ve just reconditioned the SM5 switchbox I am inclined to think this is Renaud’s antennae effect.

Is it possible to suppress the source rather than each light?  ie capacitors on the coil, dynamo etc?

Devil’s work indeed, There is something of Lucifer in most jobs on our cars.  I’ve just scraped my knuckles fitting brake cables.  A simple 1/2 hour job taking well over an hour!

Cheers

Howard

[Renaud]

Yes, I believe the muck could do it too. One must remember that a really very small intensity can make a led flash a bit.

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But in that case a capacitor would be no use!

[spannerman]

Is your car still 6v and does it do it with
The engine stopped or running or both ?