opto isolator - How to choose optocoupler - Electrical Engineering Stack Exchange
voltage - TLP280-4 Optocoupler on 12/24V inputs - Electrical Engineering Stack Exchange
3.3v To 5v/5v To 5v/12v To 5v 4 Channel Optocoupler Isolation Board Level Voltage Conversion Board Plc Signal - Integrated Circuits - AliExpress
Using Opto Couplers
80KHz 1-Channel Optocoupler Isolation Module Input 12V No Din Rail Holder PLC Processors - Pin Board - Arduino, Robotics, Raspberry Pi, ESP8266, Learning DIY, Development board ICStation
Optocoupler Isolation Board Voltage Converter 24v To 3.3v/5v To 24v/12v To 24v 4 Channel Isolated Module Plc Signal Level Board - Integrated Circuits - AliExpress