| 摘要 |
The circuit for stopping the video system when the vertical synchronous signal is unstable or the image signal is not received during certain time comprises an amplifier (1), a synchronous signal separator (2), a filter (3), a switching circuit (4), a comparator (5), a delay circuit (6), a vertical synchronous signal separator (7) , a recording control signal generator (8), and a mono/multy (9). If the circuit (7) does not separate the vertical synchronous signal, the generator (8) provides low level signal to the mono/multy (9) and this low level signal is inverted in an inverter (I1) and then applied to the temporary stop tap (PAH) so that the video system stops the operation.
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