I have salvaged, non-documented, IR LEDs. Without a datasheet I do not know how much current they can handle.
I have run into this before: I confirm the LED is good with by viewing it through a camera. I set up my circuit and begin troubleshooting. Only after eliminating all other possibilities, do I resort to a camera to discover that along the way the IR LED stopped emitting.
It would be great if I could be confident that I am using the right resistor but even then accidents happen. What I would like is a simple indicator that the IR LED is functioning without detecting its emissions.
I would prefer an "idiot" light such as a visible spectrum LED that is lit when the IR is functioning properly and can be relied on to go dark should the IR LED fail.
I was thinking that I could trigger this from a voltage drop using a transistor, pull-down resistor, and a variable pot that I could tune to toggle my visual indicator.
Is this feasible?