Electronic – How to determine the nominal current of an LED

currentcurrent measurementcurrent-ratingledmaximum-ratings

I salvaged the LED disk from a defunct LED light bulb. (The problem was an arced transformer, the LEDs are intact.) It has several unmarked white SMD LEDs soldered on it: 5 lines parallel, with 3 LEDs in series on each line.

I want to use this disk in a strobe. My aim is to get the maximum brightness out of it without damaging the LEDs. Is there any way I can determine (vaguely) its nominal current rating, rather than guessing it?

Best Answer

It has several unmarked white SMD LEDs ...

... without marking you cannot get a datasheet and without datasheet there you don't have a chance of finding out the real current.

However there is a possibility of getting a rough impression of the current needed by the LEDs:

Attach a current source and a voltage meter to the LEDs (the current source may be a voltage source with a resistor in series).

Slowly increase the current from 0A until the product of current and voltage is the power you estimate (the nominal power of the bulb multiplied by the efficiency of the transformer; maybe 5W for a 7W bulb).