MAX232 RS-232 Level Translator

An iconic charge-pump chip turns 5 V TTL UART into ±12 V RS-232 — talk to legacy GPS, modems, and industrial gear from any modern board.

Difficulty: Breadboard. Estimated build time: about 45 minutes. Estimated parts cost: about US$4.20. 3-part bill of materials with live supplier pricing. An RS-232 level translator built around the MAX232, the 1987 chip that single-handedly killed the dual ±12 V power supply in serial-port designs.