In message <199803262245.BAA13403@chat.ru>, Alex Torres <altor@CHAT.RU>
writes
>2 years ago I've posted here the schematic with single +5 power :
>                                  ______ +5v
>                            b |/e
>PIC--------/\/\/\/-------|       p-n-p tranzistor
>output                     |\c
>                                  \
>                                   |---------------------------  TxD  (to
>PC's RxD )
>                                   |       4k7      10-100mF
>                                    ---/\/\/\/\/--------||-----|
>                                                    _\/_  diode
>PIC                                                 |
>input -----/\/\/\/\---------------------------------------- RxD (to PC's
>TxD)
>

There is an 8-pin DIL chip that does all this, the Dallas DS1275. It's a
*lot* more expensive, but could be useful if space is limited, and you
need very low power consumption.

Leon
--
Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk
Amateur Radio Callsign G1HSM    Tel: +44 (0) 118 947 1424
See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850
DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.