FEEDBACK_CONTROL

Published:2009/7/14 0:22:00 Author:May | From:SeekIC

Replacement of manual phase control pot with sensor and transistor provides automatic control of load power in response to stimuli such as heat, light, pressure, or magnetic fields. Output of feedback control circuit goes to thyristor in series with load. RC establishes desired operating point for sensing resistor RS. As RS increases in resistance, more current flows into CT and makes 2N4870 UJT trigger at smaller phase angle so more power is applied to load. For opposite effect, interchange RS and RC.-D. A. Zinder, Unijunction Trigger Circuits for Gated Thyristors, Motorola, Phoenix, AZ, 1974, AN-413, p 4.



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