Do all dimmable LEDs flicker at 240fps?

Hardware
1

Hi all. I’m trying to figure out if I’m chasing an impossible dream here…

If I observe my Philips non-dimmable LEDs at 240fps (on my iPhone) I don’t see any flicker.

If I observe a Philips dimmable “WarmGlow” LED, connected to either a trailing edge dimmer, or a Fibaro 1 Dimmer (TRIAC based?) I see an obvious flicker.

I also see the same flicker with an eco-halogen, on both dimmers!

The flicker is not obvious to the naked eye, just on the camera.

Is this “normal”, or does anyone have dimmable LEDs with no flicker at 240fps?

PS. It did occur to me that the phone may be able to filter flicker at multiples of 50Hz automatically (when there’s no dimmer messing with the AC waveform) so actually all my lights flicker?

2

Even if you have a triac dimmer, it should switch on mains frequency, 100 half cycles per second. That’s because dimmers have zero crossing sensing to synch with mains.

3

Depending on the LED, flickering is how a LED is dimmed. Its part of the design.

4

Sure, and I understand that. But the PWM can run at different frequencies, which is why I’m curious to know if other people see similar effects with a high speed camera?

I guess what I really want to know is: could I have a better set up with different LEDs/dimmers, or is this as good as it gets?

5

I don’t see any flicker on my hue dimmable using an iphone to record slo-mo (its all I have). I’m dimming in software (the bulb) though and not hardware (a dimmer switch) which may have something to do with it.

My cheaper Merkury bulbs show obvious flicker at dimmer power (in software) but I totally expect this for an extremely cheap bulb.

1 Like
6

After some more experimentation, I may have answered my own question.

I moved the WarmGlow bulb to a non-dimmable switch, and it still flickered (not great).

I then dug out an old Ikea Tradfri warm/cold dimmable and linked it up to ZHA: no flicker, just a very slight “phasing” of the warm and cold colours at full brightness.

So yeah… I can definitely do better than a WarmGlow with a dimmer.

It’s frustrating, because I always aim for a fail-safe UX, and smart bulbs are basically useless when Home Assistant is offline.