I don't understand why LED rear lights flicker like a fast strobe. They are being fed 12V DC aren't they? So they have no reason to strobe. Educate me OcUK, why do they do it?
Why do LED rear lights flicker?
- Thread starter Jonny69
- Start date
I can see it quite clearly in real life, it's quite high frequency, I'd say over 30hz but I can see it. Both on brake lights and the sidelights. I've also noticed it on the new LED cats eyes in the road.
Yes, I can see both.
Doesn't make sense to me though, why PWM a LED when it's a DC device? Surely use a lower power item in the first place or is it just me that thinks powering up a load of control circuitry is kind of defeating the object of using LEDs in the first place? Or are we talking light output regulation here because the voltage is not very stable in a car? Ie it fluctuates between 11V and 14V so runs a lower duty cycle when the voltage is higher?
Well it turns out it is for constant brightness and only one drive circuit. Been chatting to an engineering buddy about it. It's also due to the cost of the smoothing capacitor that stops the flicker, apparently there's a threshold of people who simply can't see the flickering and over a certain number and the flashing is deemed acceptable. It doesn't matter about everyone else who notices ot it irritates. Ergo they save their 0.01p per unit and save the company thousands over the production run.