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Building your own level converter

To adapt 3.3 TTL logic from NAS to +15/-15 PC serial, you can build your own converter. This is the schema I used, from Sodoityourself with a two errors corrected and explicit pinout for DB-9 female.

Please note that MAX232 circuit cann't use 3.3 Vcc from serial Vcc, you must pick up 5V elsewhere (on board or from external power supply), or else use another level converter. The original schema came with Rx and Tx swapped one with each other, have a look to RS-232 datasheet if any doubt.

This schema is easy to apply on a evaluation board, so did I.


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