Why are my LEDs burning out?

The dynaohms I ordered from digikey Minnesota USA on Monday arrived at lunch today Friday. Great postal service!

Now in circuit instead of the conventional resistor I used before. See attachment for dynaohm voltage drop and led current. I will leave it on for 24 hours and then do the tests I mentioned a few posts ago.

For Brouhaha: After 24 hours all 4 LEDs lit and current steady at 23mA using a dynaohm.

I then varied the applied voltage from the psu and filmed the two meters measuring current flowing and voltage drop across the dynaohm. Current remains nice and constant at 23mA until dynaohm’s minimum voltage drop criteria is not met. See attachment.

I cannot find anything wrong with using a series circuit of 4 Leds in series with a 20mA dynaohm fed from a 24 V dc power supply.

I hope this gives you confidence in your project‘s lighting design.

(You could wire more LEDs in series and then in series with one dynaohm provided that you make sure 24V - (number of LEDs x Vforward) is a voltage greater than the minimum dynaohm voltage drop of 2.6V - assuming a 24V psu. Off the top of my head I would only design a circuit which ensured the dynaohm voltage drop is no less than say 6V to take into account variations in individual LED forward voltages and PSU output voltage. Always check first though before you assemble in your project. A 6V dynaohm volt drop would drive 6 LEDs each dropping 3V fed by a 24V psu. If the same LEDs each dropped 3.5V, then 6 would in total drop 21V leaving 3 volts across the dynaohm - greater than 2.6V but not by much margin. You get the idea. Probably best to stick at 4 or 5 LEDs in series maximum to ensure at least 6V across dynaohm if your LEDs all drop typical 3.5V.)