@dnar: Happy 47th, dnar! I'm only 4 years behind you
@solarfire: Some suggestions for the schematics:
v1/v2 - Shouldnt we be monitoring the state of the LMD18200's overtemp line with the micro, not just with a LED?
v1/v2 - Could we add support for an RTD temp sensor, as well as NTC? They are more accurate, and the small ones have VERY fast responses. Not that much more expensive than an NTC therm.
v2 - Better to use a 10 pin header instead of a DB9 connector
v2 - Suggest a MAX231 instead of 233.. Cheaper, very common, same DIP pinout as max232, and only needs 0.1uf caps.
v2 - Remember to tie unused rs232 driver TTL inputs to ground, and rs232 line side inputs to -9v
I have a PCR reactor (VERY fine temp control, better than 0.01C) kicking around at work, so I'll have a look at how it drives its peltier for some more ideas.
Cheers,
Pete