I would like to build Optoisolated RS232 interface. I’vesearched a little bit, and I came across your design:
However presented schematic is of poor quality – I’m not able to read all parts numbers and their values. Is it possible for you to send me a copy of this schematic, which is more readible?
Mail from M from Poland
You had written to me a few months back, I suggest this circuit (image in this post is a USB to rs232 isolated interface, makes more sense as RS232 have become obsolete in computers but are active in industrial interfaces)
This self powered interface circuit electrically isolates the TxD and RxD lines from the PC serial port and protect the PC from direct connection to hazardous voltages.
See also Isloated Interface to Microcontroller
See a Commercial Solution you can buy