Sorry for missing enough detail on the original thermoswitch. The original thermoswitch was a unique design that I have not seen elsewhere. The Princo thermoswitch was a modified mercury thermometer with two electrodes installed. When the temperature rises, the column of mercury comes into contact with both electrodes and completes the electric circuit. The inner oven stays within +/-0.05 degree C of 78C.
Since the design involved a mercury thermometer, the form factor is 0.25 by 4.25 inches. -----Original Message----- From: Mark Sims <[EMAIL PROTECTED]> To: time-nuts@febo.com Sent: Tue, 19 Aug 2008 1:54 pm Subject: [time-nuts] Restoring GR 1120-AB Frequency Standard - Need The original thermoswitch sounds like is is a mechanical switch, so it can't be all that accurate or stable. I would use something like one of those TO-92 temperature sensor chips. I would probably use a 8 pin micro with an A/D to read it and drive a reed relay (or transistor). Analog people would use a comparator and voltage reference chip/pot. ---------------------------------------- _________________________________________________________________ See what people are saying about Windows Live. Check out featured posts. http://www.windowslive.com/connect?ocid=TXT_TAGLM_WL_connect2_082008 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.