LED strip lights flickering when switch is off

Rebuilder

Builder of Things That Interest Me
HELP!! Anyone know what would be causing this? The LED strip lights flicker when a 12v fan is switched between speeds. The LEDs are on a dimmer and the dimmer is all the way off but they still flicker. The Fan and LEDs are on separate circuits. Any help would be appreciated. Thanks

Here's the dimmer I used if that helps.....
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NatersXJ6

Explorer
Is there a common ground wire or a shared path for the power wires? I.E. are they tied together with zip ties or anything?
 

Verkstad

Raggarkung
I dont know electronically whats going on inside that dimmer module
But I suspect the root cause of flash is from reverse current created as the motor is briefly switched off between its speed settings.
You might try installing a flyback diode across the power leads of the fanmotor.
Be sure to get polarity right.
Btw,
Describing symptoms, flash and flicker are not the same thing.
6BE26D63-B5A0-4794-B6D0-3F9FEBB28D7E.jpeg
 
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Rebuilder

Builder of Things That Interest Me
Is there a common ground wire or a shared path for the power wires? I.E. are they tied together with zip ties or anything?
Yes the wires would be next to each other from the fuse panel up past the dimmer switch but I'm not sure if they're zip tied together. I don't have the van here to check but I'm pretty sure the fan is grounded to the van body near the fan and the LEDs are grounded to the van body in the opposite corner of the van.
 

NatersXJ6

Explorer
LED strips can be so sensitive that they pick up all sorts of stray current and induced currents. In addition, many dimmers don’t really “switch” off. To Verkstad’s point above, the dimmer may or may not include a true mechanical switch inside, and that brief reverse current can transfer. If it was a single flash, I wouldn’t worry about it. If it continues flickering all the time… maybe care then.
 

Rebuilder

Builder of Things That Interest Me
I dont know electronically whats going on inside that dimmer module
But I suspect the root cause of flash is from reverse current created as the motor is briefly switched off between its speed settings.
You might try installing a flyback diode across the power leads of the fanmotor.
Be sure to get polarity right.
Btw,
Describing symptoms, flash and flicker are not the same thing.
View attachment 721610
This definitely sounds plausible. The dimmer does have a circuit board so maybe that's allowing the voltage spike to pass through even though the switch is "off"?
 

Rebuilder

Builder of Things That Interest Me
LED strips can be so sensitive that they pick up all sorts of stray current and induced currents. In addition, many dimmers don’t really “switch” off. To Verkstad’s point above, the dimmer may or may not include a true mechanical switch inside, and that brief reverse current can transfer. If it was a single flash, I wouldn’t worry about it. If it continues flickering all the time… maybe care then.
Yeah I'm thinking the circuit board in the dimmer isn't a compete disconnect when switched off. I think I'll try the Flyback Diode so I'll know for sure.
 

NatersXJ6

Explorer
I spent the better part of 6 months and $400 learning the hard way about electronic controls for my “automatic” garage lights with all sorts of current leakage learning events. The concepts aren’t exactly scaleable… but they are close. You could also just add a mechanical switch inline with the dimmer. I use lamp cord and the little rotary switch that interrupts the cord for most of my LED strips.
 

IdaSHO

IDACAMPER
LEDs are VERY sensitive.

A few years ago we missed our destination due to a road closure and made due with an open spot on public lands under some high voltage lines.
We didnt mind the constant buzz.... but the interior LED lights glowing all night was a different story. :ROFLMAO:

 
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