Hi,
electronics works with voltage and current. you can´t calculate with "glow" or "faulty".
This is why there are datasheets. full of usueful values.
You need to specify at which input voltage RMS you want the LED safely to be OFF.
You need to specify at which input voltage RMS you want the LED safely to be ON.
(inbetween there is a grey area, LED might be OFF, dimmed, or ON)
*********
Input side resistors. Max current = min resistor value:
Optocoupler datasheets tells the max. input (LED) recommended operating current..
Input voltage is up to 280V RMS, this means 280V x 1.414 peak voltage.
Now it´s just ohm´s law: R = V / I --> R_L_min = peak_input_voltage / max_input_current.
Power dissipation of resistor: P = V^2 / R = 280V^2 / R_L
****
Go on this way.
Klaus
Hi,
sadly still no useful specifications.
Your calculation of the resistor is wrong.
You calculated 5.5kOhms.
this gives 280V/5500Ohms = 50.1mA
According datasheet 50mA is the absolute maximum limit. Once you cross this limit, just for a short moment - you risk to kill the device.
50mA is NOT the usual operating current.
Now you should know that 280V is the RMS voltage and thus the maximum voltage is 280V x 1.414 = 396V
at 5.5kOhms this gives a maximum current of about 72mA --> expect the PC814 to be killed sooner or later.
The dissipated of the resistor power is in the range of 14W --> thus the 2W resistor will be killed, too.
This is very basic electronics stuff. You really should know this .. especially when dealing with dangerous high voltage.
I expect there is even more lack of technical knowledge... thus you risk your and other´s lives.
Please learn how to calculate and deal with voltage, current, resistance, power, AC waveform.. and how to treat dangerous high voltage (circuits)...
Klaus
you could go for say 3mA opto LED current at mains peak (the minimum mains peak of the minimum mains that you want to bother detecting)
So mains peak at 160 vac is 226V.
So do 0.003 = 226/R
That gives you R.
Then be sure you size the opto transistor side pullup resistor to sucessfully get pulled down low enough when this 3mA flows...so you will have to see what is the min CTR at this 3mA current level.
Or are you doing a mains zero cross detector...if so, then you will have to do a bit of timing between highs and lows to get the zero cross.
You had a working configuration in post #3. Looks like you are trying hard to change it to non-working…
It's no problem to connect the controller input either to collector (inverting operation) or emitter (non-inverting). But there must be load resistor carrying the opto coupler output current. R17 in post #13 is an input series but no load resistor.
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