| 摘要 |
PURPOSE:To protect a call signal equipment from destruction by monitoring an auxiliary winding voltage at the secondary side of a ring choke converter, driving a stop control means through optical coupling when the voltage reaches an overvoltage so as to drive a control transistor(TR) thereby stopping the operation of a main TR. CONSTITUTION:A main TR 12 is subjected to ON/OFF operation at a prescribed period by a feedback voltage of a transformer 15 and the control of a control TR, a high DC voltage as an output is fed to a call signal generating section 17, which is controlled by a 20Hz input signal to generate a call signal. When an overvoltage detection means 16 coupled with an auxiliary winding of the secondary side of the control TR 13 detects an output voltage of a prescribed value or over, an optical output is generated and a stop control means 14 receives a light to turn on the control TR 13. Thus, no output voltage is generated from the transformer 15 and no overvoltage is fed to a load.
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