Digital Data Aquisition and Control unit.
 

Happy days.

The DAQ PCB is complete. One cock-up, connected the LED backwards and it is now a short circuit.

http://w1.863.telia.com/~u86303493/C...m/daq_done.jpg


An evenings work of soldering.

First tests are very promising. I have connected two thermistors and started logging data.

http://w1.863.telia.com/~u86303493/C...irstDAQLog.jpg

This is a chart of the first log. The low spike is a squirt of butane, the high spikes are my finger-tip temperature. The thermistors are very sensitive.
The range of the High res channel is about 20 C/12bits resolution, quite linear. The low res channel range is about 200 C but the linear-ish part of the scale is between 0 and 70 degrees.

I'll post details of this with theoretical thermistor curves later. When I get some calibration going I will test the thermistor theory and get some idea of accuracy.

The noise is low. Very low in my opinion, ~1 or 2 LS bits 3*sigma, far better than I expected, this represents ~0.025-0.05 and 0.005-0.01 deg C of noise for the low and High res channels respectively. I will get an idea of repeatability over the coming days.

Very happy so far.

Haven't tested the PWM, ammeter or volt meter yet. It's late and work tomorrow.