| 摘要 |
PURPOSE:To simplify the circuit constitution, by constituting frequency discriminating circuit as a circuit without hysteresis characteristics at recording, in a device automatically recroding and reproducing video signals with different frequency in vertical synchronizing signal. CONSTITUTION:A switch circuit 5 is provided for a frequency discriminating circuit 4 having a hysteresis characteristic, and the switch circuit 5 is conductive at reproduction, an output of the circuit 4 is fed back, the check characteristic is provided with the hysteresis characteristic, and the switch circuit 5 is cut off at recording to avoid the hysteresis characteristic for the check characteristic, allowing to discriminate video signals at recording easily. Thus, the frequency discriminating circuit for recording signals can be omitted. |
