| 摘要 |
PURPOSE:To increase the noise resistance and at the same time to lower the modulus of faults, by detecting the voltage drop of the terminal of a capacitor after rectifying the output pulse of a transformer and then charging the capacitor with the output of rectification. CONSTITUTION:A dial pulse train supplied to an input terminal I is applied to the primary winding of a transformer T via a gate G, and the periodical transient voltage is generated at the secondary side. Diodes D1 and D2 give the full- wave rectification to the transient voltage, and the transient voltage charges a capacitor C2 via a resistance 3. As a result, the terminal voltage of the C2 rises up. Thus a transistor Q conducts, and the level of an output terminal O is lowered down approximately to a ground potential. Therefore the continuation of the dial pulse train can be known by monitoring the fact that the terminal O is at the ground potential. |
