As agreed with the author, Mike Virgiliev's RS232-TTY converter schematics is now available for download at "http://www.runmode.com/downloads/rs232_tty.zip":http://www.runmode.com/downloads/rs232_tty.zip
Thanks all guys here, who asked me for circuit diagram, and about performance details. It was nice chance to correct some small problems with Signal Ground/Earth designation. I corrected SG/Earth designation and have added some comments, hopefully important for all, who are not
circuit designers by nature or profession.