As mentioned in the answer to this question:

LED bulbs and LED dimmer

we can't trust a LED driver / LEDs to be dimmable if it doesn't say so explicitly. However, only some companies offer explicitly dimmable LED products, while for others it's not clear whether they only make non-dimmable LED-related products, or whether they just don't bother with it and hence don't certify anything as dimmable.

My question: Suppose I have a LED driver, driving an array of LED bulbs/units/whachamacallit which take DC. Is there a way to safely (or with-low-risk) experiment with dimming it?

If so - I'm willing to get relevant custom equipment provided it's not super-expensive.


For AC powered screw-in LEDs, making them dimmable is hard. So nobody makes an AC dimmable LED by accident and forgets to list it as dimmable. Forget that.

DC is a whole different kettle of fish

All the rules are different with DC. Not least the cabling/wiring rules for circuits under 55 watts.

However, the way dimming works is also totally different. There is no need to deal with the balky AC waveform, nor any legacy need to play well with a 1960s-tech dimming scheme intended for incandescents.

DC dimming is typically done with PWM, meaning the power supply is switched on and off, faster than the eye can see.

Control is done via this same exact PWM. A dimmer/controller's output can either control a small amount of lighting, or be the pilot signal to an amplifier that controls a great deal more lighting, or a combination of both.

The market is awash with cheap Cheese junk, but functionally compatible products are also made and UL-listed by reputable makers.

Also, LED is available in full color RGB and RGBW, the same basic scheme except with 3-4 channels for red, green, blue and optionally white.

  • You're saying PWM controls the effective intensity of each of the LEDs? Interesting. Actually it's a bit creepy, but interesting. Good thing I'm not epileptic. ... regardless of all that: Are you saying that those DC drivers never "take a hint" from old-style AC dimming to dim accordingly?
    – einpoklum
    Feb 2 '19 at 20:18
  • 2
    @einpoklum Difference being old school dimming flickers at 60 or 120 Hz, and LED dimming flashes at 5000 Hz or so. The former is a known problem that makes old fluorescent ballasts uncomfortable for many. The latter would bother epileptics, if they also happen to be The Flash... Feb 2 '19 at 21:31

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