I am attempting to add a signal activity LED to my dummy load box. I have constructed the following circuit and so far it does what it is supposed to (lights an LED with signal applied and does not interfere with overall load impedance). I am now trying to tune the circuit to turn on at appropriate level and not over-current the LED at higher signals. I am using a 3mm red LED with max current of 30mA, which is what I get when the load box sees a 100V peak to peak signal, about the largest signal the load box will see. The LED currently does not turn on until load box sees ~12.6V peak to peak signal, I would like the LED to turn on at ~5V peak to peak. Is there a way to accomplish this while still allowing 100V peak to peak signals without toasting the LED?
This is my current circuit:
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simulate this circuit – Schematic created using CircuitLab
If possible the LED would need to come on at ~5V peak to peak and then increase in light intensity up until 100V peak to peak. My main issue as noted is that I’m already nearing the LEDs maximum current (30mA) at 100V peak to peak and the LED does not turn on until ~12.6V peak to peak.
