Led lights flickering when off!

[Chris KC]

Possibly Howard but in electronickery His presence is strong... Get thee gone Satan!!

[Renaud]

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

Yes, good question!

[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

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Oooops

That repl got sent again.  Sorry

Howard

[Renaud]

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

---

Oooops

That repl got sent again.  Sorry


Howard

About working on the source (s?). One could suspect either the dynamo or the ignition as an electro-magnetci radiation. It would be simple to disconnect the dynamo. Again there capacitors could help.

[Tony Press]

All I can sat is serve you right for deviating from the true path of proper fillament globes

May the Lord (Austin) have pity on you 

[Bob Culver]

The radiation from original distributors is formidable. "Modern" cars had resistive carbon centres. Could try a cheap carbon radio resistor 5000 ohm or so temp wired into the HT lead at coil and if it works try and acquire an inline one if still available.
I dunno what Sevens do to Pacemakers but my car could affect analogue TV picture at 100 yards!

[Robert Leigh]

I had the same problem on a Riley where most of the under bonnet wiring goes through metal trunking. I rerouted the HT outside the trunking to cure the problem. I suspect that if your lighting wires were connected using screened cable the problem would disappear. Possibly the use of aluminium wound cable as supplied for the purists restorations would be satisfactory.

[AustinWood]

We have all almost LEDs in the Austin and no problems at all.
They are very sensitive to earthing and also to having a mixture of LED and incandescent on the same circuits.
I don't know if this helps but I have an LED light in the house that flickers when it's off.
It's operated from two switches, one downstairs, one upstairs. Thus there are 2 off positions & 2 on positions. It only flickers in one of the off positions. If it's flickering operating both switches, one to switch it on & the other to switch it off stops the flickering.
This implies that the way in which the light is connected is the cause.

[John Cornforth]

Hi Howard

LEDs can produce noticeable light with very little current, and can turn on and off incredibly quickly. I suspect you have voltage spikes on the switched side of the wiring which are coming across the open switch from the battery/dynamo side. This is most likely via the small capacitance across the switch contacts, or capacitance between switched and unswitched wiring running alongside each other. Simplistically these spikes/pulses are AC, which unlike DC can flow through a capacitor. All A7's have voltage spikes on the 6V line, coming mostly from the ignition coil (if fitted) and the dynamo.

I recommend you connect a capacitor from the switched side of the coil to ground. This will short circuit the rapid spikes whilst not affecting the steady DC. You could also try capacitors on the switched side of each lighting circuit. The capacitance value isn't critical, anything between 0.1 uF (microfarad) and 10 uF would probably do. Radio type capacitors would work, but aren't as easy to get since Maplin disappeared. Automotive suppressor capacitors are more convenient to mount and wire in. They aren't so prevalent these days but can be found online. An ignition condenser (= capacitor) would also work. Keep the ground lead short.

Rather less likely is direct interference from the HT side of the ignition, radiated by the copper HT cables used by A7s. In this case, I find resistor suppressors of 5000 to 10000 ohms mounted between the leads and the sparking plugs are quite effective. "Champion" style right angle types ought to work, but beware that many of them are poorly made copies. I suggest checking their resistance with an ohmmeter before fitting, if you go down that route. Be aware that it's generally reckoned not to be a good idea to fit resistor suppressors to Magneto systems.

With all problems of this nature, some experimentation is needed, so best to "tack on" components initially and then make a more permanent solution when the best setup is found.

[spannerman]

It will only be a few ma available so
shunt it to earth by say a 1k ohm
1/2 watt resistor across each feed
To the lights that will stop the
leds flickering