5V to 3.3V logic level translation/conversion/shifting: how to interface a 5V output to a 3.3V input. – next-hack.com
opto isolator - what is the reason behind DC level shift of the optoisolator ouput(collector of photo transistor) terminal? - Electrical Engineering Stack Exchange
logic level shifter - General Electronics - Arduino Forum
Optocouplers for TTL-CMOS Logic Level Shifting
4 Channel Voltage Level Shifter Translator Optocoupler Isolation Board PLC Signal 4Bit Converter Module 24V to 5V
4 Channel Voltage Level Shifter Translator Optocoupler Isolation Board PLC Signal 4Bit Converter Module 24V to 5V
esp8266 - Logic Level Shifter 24/12 V to 3.3 V - Electrical Engineering Stack Exchange
4 channel level shifter/optocoupler from ICStation.com - YouTube
Optocouplers for TTL-CMOS Logic Level Shifting
SOLVED] How to build level shifter 3.3v to 24v - General Electronics - Arduino Forum
5V to 3.3V logic level translation/conversion/shifting: how to interface a 5V output to a 3.3V input. – next-hack.com
Amazon.com: IS Icstation 24V to 5V 8 Channel PLC-PNP Signal Converter, Optocoupler Isolation Board, Voltage Level Converter Module : Industrial & Scientific
5V to 3.3V logic level translation/conversion/shifting: how to interface a 5V output to a 3.3V input. – next-hack.com
Optocoupler with isolation 3.3V/5V/12V/24V voltage converter – Techfun.sk – At least the Arduino shop