DIYbanter - View Single Post - Using a non-dimming LED bulb on a dimmer

Rob[_40_]

wrote:
I have a clip on light that I want to use temporarily for light in a
room I am redoing. The fixture has a dimmer on it, but I dont want to
dim it, just leave it on full brightness.

Can I use a non-dimming LED bulb on this fixture as long as it's left on
full brightness, or will the dimmer damage something just because it's
there?

I've never used a dimmer on LED bulbs, so I am not sure.
If it's a problem, I'll just use an incandescent bulb, since this is
only for a few days anyhow, until I get some permanent lights installed
in the room.

And just for the heck of knowing, what does happen if someone dims the
non-dimming LED bulbs?

It depends on the bulb, but usually these non-dimming bulbs will have
a "capacitive dropper" circuit: the input of the bulb has a series
capacitor, followed by a bridge rectifier, and the LEDs in the bulb
connected in series on the DC output of the rectifier.

The result is that the LED current is determined by the derivative
of the current. This works fine on a sinewave, but the output of a
dimmer has steep edges so the current peaks will be much higher at that
point and the LEDs will burn.