| 摘要 |
An amplifier provides a complete video and sound I.F. signal to a synchronous detector switching circuit, and the switching signal to be applied to the switching circuit is obtained from the same amplifier by connecting a grounded base stage, with its emitter impedance, in series with the amplifier load. The grounded base stage has a load tuned to the I.F. carrier frequency, and the filtered signal from the grounded base is the signal applied as the switching signal to the synchronous detector switching circuit.
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