Just done a few tests at work on our Fluke 5520A calibrator with the led's with and without the series 1N4007 diode.
Ammeter used was a Fluke 75 DMM.
Circuit as per diagramme listed in this thread.
230 Volts 50 Hz 78 kilo ohms and 1N4007 1.27 mA 0.132 Watts.
230 Volts 50 Hz 78 kilo ohms 2.8mA 0.612 Watts.
117 Volts 60 Hz 39 kilo ohms and 1N4007 1.28 mA 0.064 Watts.
117 Volts 60 hz 39 kilo ohms 2.8mA 0.31 Watts.
formula P=I²R
It proves the fact that the 1N4007 series diode reduces current and power dissipation in the series resistors by a quarter with no loss of light output in the LED.
Frequency 50 or 60 hz does not affect the current drawn in the circuit because it is a resistive circuit.
Regards Raymond
