Browse Prior Art Database

Temperature Controller

IP.com Disclosure Number: IPCOM000095677D
Original Publication Date: 1964-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Halperin, A: AUTHOR [+2]

Abstract

The temperature of the environment of the heater element R1 is maintained constant as a result of the change in current from the controller due to the effect of thermistor Rth. This is located so as to be responsive to the temperature of R1.

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Temperature Controller

The temperature of the environment of the heater element R1 is maintained constant as a result of the change in current from the controller due to the effect of thermistor Rth. This is located so as to be responsive to the temperature of R1.

DC voltage for the temperature controller is provided across capacitor C1 from the AC line via transformer T and diodes D1 and D2. The base to emitter voltage of transistor Q2 provides a reference voltage. This is also used as the input to a feedback amplifier incorporating transistors Q1 and Q2. When there is a change in the temperature of R1, there is a simultaneous change in the resistance of the thermistor Rth. Such change tends to change the current through variable resistance R3 and thermistor Rth as well as the base to emitter voltage of transistor Q2.

This tends to change the base current in transistor Q2 and its collector current which, in turn, tends to change the base current in transistor Q1 with the resulting change in its collector current. The change in collector current of transistor Q1 is present in load resistance R1 in a manner to correct the initial temperature change. Thus, the effect of external influences on the temperature of load resistance R1 is reduced by a factor dependent on the gain of the feedback amplifier and the sensitivity of thermistor Rth.

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