I have this design. By a possible mistake from user, the circuit would receive 12 V AC, and may destroy the optotransistor on reverse voltage cicle.
I can put a diode D1 before the resistor, but the diodes I already know, may have voltage drop or resist just small currents (300 mA), but the AC source can have 2000 mA.
I need a Diode with Low Voltage drop.
The low voltage drop is required to can handle the logical input at right side.
The 5.0 volts is not a source, it comes from a switch connected to a device sealed. When optocoupler gets on, the logical inputs receive a signal and the device acts.
Which diode can I use?