I am thinking about how to galvanic isolate a serial RS232 connection using 4N25 optocouplers.
The connection is 19k2 baud, so the 4N25 should be fast enough.
I know about the inverting problem if using them in the traditional way (output pulled LOW when input signal is HIGH), but here is some very interesting analysis about a non inverting circuit:
Has someone tried using this setup?
One could limit the current flow through R2 by increasing it (@5V it is around 15mA!), but that of course has side effects on the rise and fall flanks as well as the voltage levels.
LTspice shows that 1k2 ohm might just work if working with 3V3 on the receiving side.
Any reports? Ideas? Comments?