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It's quite easy to calculate resistor power when the applied voltage is a direct or rectified sine.
Resistor temperature at rated power may be much higher than assumed 70°C, depending on the type. It's usually not specified in datasheets, but you get an idea if they specify a derating curve.
If you finally achieve a waveform like in post #14, please check if it's maintained with parameter variation. LED intensity undergoes aging and transfer ratio is also temperature dependent.
Anotuer important point, mains waveform can be distorted. dV/dt at zero crossing can increase. Worst case the zero crossing pulse at OC output may disappear.
Resistor temperature at rated power may be much higher than assumed 70°C, depending on the type. It's usually not specified in datasheets, but you get an idea if they specify a derating curve.
If you finally achieve a waveform like in post #14, please check if it's maintained with parameter variation. LED intensity undergoes aging and transfer ratio is also temperature dependent.
Anotuer important point, mains waveform can be distorted. dV/dt at zero crossing can increase. Worst case the zero crossing pulse at OC output may disappear.
