| 摘要 |
PURPOSE:To eliminate the trouble of a switching operation and an inconvenience accompanied with a cable wiring by switching a change-over switch from the receiving signal of a TV antenna to the output side of an RF modulation circuit by means of a power supply from a video apparatus. CONSTITUTION:The power supply voltage Vcc, which is supplied from a VTR 1 to an RF modulator unit 2, is the switching control signal of an electronic switch 4 as well. When the unit 2 is connected to the VTR 1 and the power supply of the VTR 1 is turned on, the power supply voltage Vcc is supplied to the electronic switch 4, and its change-over contact 4c is switched to the side of a terminal 4a, and the output of the RF modulator 3, i.e., the regenerated signal of the VTR 1 is selected by the change-over switch 4, and is led to a monitor TV 6. When the power supply of the VTR 1 is disconnected or the unit 2 is detached from the VTR 1, the power supply voltage Vcc disappears, and the change-over contact 4c of the electronic change-over switch 4 is automatically reset to the side of the change-over terminal 4b, i.e., the output side of the TV antenna 5.
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