Presumably you didn't see any light emission from them during testing. LEDs can also exhibit a photo-voltaic effect. Is it possible that your diodes are infra-red LEDs? Or did your tests eliminate that possibility?They are, by testing them , photo-voltaic diodes
Most don't. That's a high reliability package. If you have phototransistors, you can use them to see if the components emit light in the range that they're sensitive to. You might also be able to use your smartphone if they're UV.Absolutely nothing marked on them.
That is old-fashioned advice that works sometimes.If there is no visible output, use a smart phone in camera mode and look for output.
by Jake Hertz
by Jake Hertz
by Jake Hertz