[time-nuts] Any experienced HP 2804A thermometer users outthere?

Mark Sims holrum at hotmail.com
Sun Jan 25 00:19:22 EST 2009

My favorite temperature measuring system is the AD537 voltage to frequency converter.  It has an on-chip temp sensor or it can be used with an external thermistor.  The chip is usually found in a TO5 can,  so the on-chip sensor has a fairly high thermal mass.  Thermistors can provide a near instantaneous response if you use a small enough device (you can get thermistors that are nearly microscopic in size).  You can easily get microdegree resolution with hardware any time nut has.  

The biggest problem is calibrating it if you need absolute accuracy.   You could do a comparison with the 2804A.  Or a three point calibration at the triple points of ice and gallium along with boiling water (compensated for air prerssure, etc)...  but then triple point cells are not in most pepole's bag 'o tricks...
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