Fig 1. Transceiver with 2 transistor
The circuit below
use MAX232 which is the MAXIM’s devices.This circuit is very stable and use for professional design. This device is inexpensive and it can provides 2 channel for RS232 .
The MAX232 line
drivers/receivers are designed for RS-232 and V.28
communications in harsh environments. Each
transmitter output and receiver input is protected
against ?15kV electrostatic discharge (ESD) shocks,
without latchup.It can operate from a Single +5V Power Supply.
Fig 2. Use MAX232 for RS232 transceiver
This RS232 transceiver circuit use DS275 which is a small half duplex transceiver chip.I Compatible with RS–232–E signals and suitible for Low–power serial transmitter/receiver for battery-
backed application.Requies no external devices.