Line-Output Transformer Short-Circuit Detection Circuit Diagram

Published:2011/7/4 10:06:00 Author:Vicky | Keyword: Line-OutputTransformer, Short-Circuit Detection | From:SeekIC

As part of the line-output transformer short-cut detection circuit, dropout pulse is composed of 555, BG4, C6, and R9 etc. When the transformer works normally, the timing cycle of monostable timing circuit which is made of 555, R9 and C6 is longer than the cycle of input trigger pulse. Therefore, under continuous triggering, pin 3 of 555 presents high level (about +5V) continuously, luminous diode LED2 (green) is lighted to the line-out transformer works well without short circuit or punch-through. If there is short circuit of punch-through, then because of mutual-inductor among the transformer windings, the transformer presents low impedance, high-damping, and the oscillator stops working. The correspondent 555 gives out low level through pin ③ for pin ② cannot receive trigger signal. Then the luminous diode LED1 (red) is lightened to indicate the abnormality of the transformer.



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