A-D and D-A converters
Central Processing Units and Microcontrollers
Drivers and level shifters
MAX232, MAX232A5V RS232 transceiver.
To operate, connect two capacitors to the C1 and C2 pins, one between the V- and GND, and one between V+ and GND. For the MAX232, capacitors should be 10uF, for the MAX232A 100nF is enough.