ECN Forum Forums General Topics of the Trade General Discussion Area Strobing LEDs

I have Recessed Lighting in my Kitchen with Dimmable (I think) LEDs and Rotary Dimmers supposedly compatible with LEDs.

The other day, for some reason the Dimmer was dimmed way down and I thought it was off. Later that day the 3 LEDs in that row started strobing one at a time in sequence from right to left over and over again.

I can maybe understand why they might turn on and off, but why one at a time and in sequence??

Any ideas?

I'll venture a guess....

Are they wired in the same sequence as they are strobing?

Is the dimmer still at 'way down' ?

Did you turn the dimmer up?

A strange/odd voltage situation; sufficient to 'fire' one, that drops off, sufficient for #2, that fires and drops, etc.

Just a guess

Hopefully Greg will get back here soon...

It's been many years since they were wired, but I would quess the're wired in the same sequence.

Sometimes the lights are left dimmed down overnight and I turn them off in the morning because the kitchen is very bright from the skylights. That day I didn't turn the switch off because the bulbs weren't lit in the morning so I assumed it was off and it stayed that way all day until the Mrs came home and thought I was playing some early Halloween trick.

I'm not sure if strobing is the right word for what they were doing. One turned on and then off and the next and next and then back to the first one. It only happened when the dimmer was in a very specific position.

That night I was able to repeat it several times by finding that specific position. Since then I tried a couple times but haven't been able to repeat it yet. They appear to be working normally.

I still vote for some type of voltage drop cause. Please keep in mind that I do not profess knowledge in the 'lectronics' (diodes, etc.) I'm a #12 to 750KCMil guy, always was, and always will be.

Another guess:

I wonder if it is not due to poor driver for the LED. The capacitors not able to retain the charge long enough so allowing you to see a really bad ripple. Could also be caused by cold solder joints.

_______________________
Shane

Sounds more like John's idea. The power supplies are charging up until one fires then it is done then the next one fires. It is interesting that they go in sequence tho. I would expect that to be more random.

Good to hear from you Greg! We were worried about you down there in FL.

It was exciting in a "Voyage to the bottom of the sea" sort of way.

Dimmers can have minimum current requirements, and if these dimmers were originally meant for use with incandescent bulbs, the LED lights in that row might not be drawing enough current at low dimming levels to keep the dimmer control stable. Doesn't explain why the lights strobe in sequence, but that could be some odd consequence.

Thanks for the replies Guys, yes, it was very strange. If I can get it to happen again I'll take a video.

I had just replaced the Rotary Dimmers which said they're good for use on Dimmable LEDs, but they were the cheapest available at HD.