Mark Sims wrote: > For your temperature sensor and/or ADC consider the Analog Devices AD537 > voltage to frequency converter chip. It has an onboard temperature sensor or > could be interfaced to a thermistor, etc. The on chip sensor has a fairly > large thermal mass. If you need instantaneous response to temperature use a > very small thermistor. > > Since the output is frequency, any time nut worth his/her/its salt should be > able to come up with a suitable counter circuit. One system that I did had > the V/F freq set around 200 Hz. Counting a 16 MHz clock over 256 cycles of > V/F waveform yielded microdegree resolution. > ---------------------------------------- > > Mark
The AD537 has too much drift and too little sensitivity to reliably maintain the oven temperature (at the sensor) to within a few millidegrees. The internal dissipation of other circuitry within the chip will increase the sensor temperature offset from the temperature being measured. A thermistor bridge is a better idea as it can have high stability and sensitivity (about 10x that of an RTD). Bruce _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
