Browse Prior Art Database

Heater Control Circuit

IP.com Disclosure Number: IPCOM000077954D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Ernst, LM: AUTHOR [+2]

Abstract

The temperature of a heated device is controlled by a triac 11, which is controlled by digital logic 12 in response to an over-temperature, under-temperature thermostatic switch 13 to selectively deliver complete half-waves of current to heating device 14. Digital logic 12 is isolated from the heater power circuitry by input pulse transformer 15 and output pulse transformer 16. Zero-crossing circuit 17 times the generation of output pulses from digital logic 12 through pulse transformer 16, to synchronize the output of digital logic 12 with the arrival of the current wave at the triac 11.

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Heater Control Circuit

The temperature of a heated device is controlled by a triac 11, which is controlled by digital logic 12 in response to an over-temperature, under- temperature thermostatic switch 13 to selectively deliver complete half-waves of current to heating device 14. Digital logic 12 is isolated from the heater power circuitry by input pulse transformer 15 and output pulse transformer 16. Zero- crossing circuit 17 times the generation of output pulses from digital logic 12 through pulse transformer 16, to synchronize the output of digital logic 12 with the arrival of the current wave at the triac 11.

An under-temperature condition sensed by switch 13 causes digital logic 12 to continuously deliver control pulses to triac 11, to thereby cause conduction of all half-waves presented to it. An over-temperature condition sensed by switch 13 combines with an n digit counter 18 in the machine logic 12, to deliver one complete half-wave of current through triac 11 to heater 14 out of each group of n half waves presented to the triac 11. Heater 14 thus operates either at a full power or a low-power level to either heat or cool the control temperature of the control device about a predetermined temperature.

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