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??
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.
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.
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.
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.
That's an interesting effect you noted there. I suspect that you're substantially beyond 90 degrees of phase delay and just barely above the voltage needed to feed driver output. The input impedance of each lamp would change during the seconds that it takes to charge up to the point where the LEDs are pulsed. It makes sense that they would fall into sequence and balance out, rather than all draw peak charging currents at once. Joe
