I just fired it up and it was registering a high level. Turned on TEMA with mixed air to settle down the levels. Gone from 2500 down to 1300 in about 30 min, so it is recalibrating itself.

In getting the connector figured out, man... I had to use a 10x scope to see if there was any traces on the board. Saw what was wired on the board and used my common sense to make a cable. No problem... nailed it the first time. pins 1,2,3 (l-r) on the sensor and 2,3,5 on the DB9 (not the right order)

I'm hoping that the sensor settles down to what should be about 500ppm in the room with outside/inside air mix.

I have actually built a controler that switches the fan, the lights, senses temprature swing of 10 degrees, switches the CO2 on/off, and detects darkness (no CO2 at night) for about 40 bucks... whats that a 350 dollar savings!! I should post the schematics for this... might be over the head of others, but some might be able to understand this. Now just have to get the CO2 tank filled.

Also - If I can't get it self-recalibrated, could I just use canned nitrogen as a zero point reference gas?

Thanks... All this to grow tomatoes :thumbsup:

Back to Bar-B-Barn for a drink!