PHASE_FIRED_SCR_CONTROL

Published:2009/7/8 1:49:00 Author:May | From:SeekIC

Can provide linear thermal control to 0.001℃ at high power with good efficiency. Band-gap voltage reference of AD580 IC temperature transducer furnishes power to bridge circuit, while platinum sensor provides sensing function, AD504 opamp amplifies bridge output for biasing 2N2907 transistor which in turn controis 60-Hz synchronized UJT oscillator that drives gate of SCR through isolation transformer. Biasing action makes SCR fire at different points on AC waveform as required for precise control of oven heater. Possibledrawback is RF noise generated because SCR chops in middle of wave-form,-J. Williams, Designer's Guide to: Temperature Control, EDNMagazine, June 20, 1977, p87-95.



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