Incoherent
10-07-2004, 06:12 PM
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/Computer/diesim/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/Computer/diesim/firstDAQLog.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.
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/Computer/diesim/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/Computer/diesim/firstDAQLog.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.