I am building a primitive optocoupler to sense if a bulb has blown/if current is flowing. It receives either 230VAC or 230VDC (rectified..) as supply.
I have calculated and built a voltage divider as pictured, but I am getting no LED action on 230AC tests, would dearly love any tips on how to get it working, but still keep it "primitive" simple as a design consideration :D So what's wrong with this picture?!
Details: The bulb measures 77 Ohm across the filament, and acts as a resistor (R2) in my calculations (and as the switch..).
R1 (two resistors in parralell) is 3 Ohm as measured-. I calculate 11V@230V AC and 17V@460DC, as the voltage across the LED (but measure nothing..)
I plan to buy a 5W, 1.7 Ohm to get a more manageable 5V / 10V combo, and choose the LED resistor accordingly.
I will put a rectifying diode in series with the led I think.. Is there any advantage crossing two LEDS to get a steady light on AC, or should I just smooth the 60hz signal with cap on the LDR side?