Dimming my LED mirror

LichtAn · 2018-08-14T20:39:47.000Z

So we got this LED mirror in the bathroom which is way too bright. You get afterimages of the LED ring for 10 minutes straight. I opned it up and found a LED strip. It is powered by 3xAAA batteries. Can I just put a resistor in there to make it dimmer? If yes, how to find the right resistor?

Here are the pictures: https://imgur.com/a/FKBPFsC

Ulrich · 2018-08-14T21:01:21.000Z

In this simple circuit a resistor in line with the batteries could do it. You can try some resistor from old electronic device or an adjustable one to find the right value. Or you try to put only two batteries inside and bridge the third ones place.

Regards Ulrich

LichtAn · 2018-08-14T21:04:30.000Z

In what range would the variable resistor be? Any estimates possible?

Ulrich · 2018-08-14T21:11:05.000Z

No chance without more information about the existing system, but I am not a electronic pro.
Try first to leave one battery away.

LichtAn · 2018-08-14T21:16:42.000Z

That’ll be too low. The batteries come out with ~1V each when it shuts off.

LichtAn · 2018-08-15T11:57:34.000Z

I got the LED strip with 16 LEDs in parallel and every LED has a 300 ohm resistor in series, so my whole strip has 18.75 ohm.
My 3xAAA batteries give me roughly 4.5V when fully loaded. This equals to 15mA to every LED or 240mA to the whole strip.

If I put a 2.2 ohm resistor in series to the whole LED strip, I end up with 20.95 ohm and the 2.2 Ohm resistor should drop the voltage by ~0.47V and uses ~100mW of power?
I hope anyone can follow me and tell me if I’m the right ballpark.

P.S.: If it is not welcome to discuss such “newbie” things here, feel free to tell me. I don’t want to be that guy…