| 摘要 |
The invention relates to a device for preventing the oscillation when no signals are supplied to a VCR. A switching circuit is designed to prevent any oscillation from occurring even though a noise signal due to a signal not being supplied is generated i na feedback loop formed between the aural signal input and output terminals of the VCR and the TV. According to the invention, the transmission line of the buffer operated by the emitter follower is formed between the aural signal input and output terminals of the VCR separately from the transmission line passing through the tuner/line transfer switch and the amplifier. In the normal condition under which the vertical synchronizing signal is detected, a feedback loop is formed through the transmission line passing through the tuner/line transfer switch and the amplifier. In the no signal state in which the vertical synchronizing signal is note detected, a feedback loop is formed through the transmission line of the buffer, so that oscillation does not occur when a signal is not supplied and thereby the oscillating noise signal is prevented from being output.
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