Current Loop to RS-232 Converter


I made 2 different types of current loop to RS-232 converters, but I ended up using this design, mainly because it uses true RS-232 signal levels (MAX-232) and uses opto-isolators especially made for current loop interfacing (even though opto-isolators are not really necessary). It uses a 12 VDC wall wart power supply. Here’s the schematic: