| 摘要 |
PURPOSE:To output a signal having a certain amplitude by including a control voltage generating circuit which generates a control voltage based on a video signal and a control circuit which varies the degree of amplification of the video signal based on the control voltage. CONSTITUTION:The video signal inputted from a video signal input terminal 1 passes a buffer circuit 7 and is inputted to a resonance circuit 9a. The magnitude of a horizontal synchronizing signal component of the video signal is proportional to that of the video signal, and a voltage proportional to the magnitude of the synchronizing signal is generated in the resonance circuit 9a. This voltage is rectified by a diode 10 and is smoothed through a smoothing circuit 12a to generate the control voltage. This control voltage is supplied to a control circuit 13 to synchronously vary the degree of amplification of the video signal in relation to the control voltage. Thus, the magnitude of the video signal is made constant at the signal output point 14 of the control circuit 13.
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