Scanner squelch (CB9424E)

Found in Popular Electronics from the 90s, this circuit mutes a scanner's speaker in the absence of a voice signal, thus eliminating the hiss.

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Amplifier with the TAA370 (CB6277E)
This amplifier for hearing aid was found in a 1968 documentation using an integrated of the time....
9-Band Current Meter with the CA3140 (CB12315E)
We obtained this circuit from a 1993 documentation. The circuit has 9 current ranges that are...
Simplex Optical Data Transmitter (CB15958E)
In the figure we have the transmitter of a data transmission system with optical fiber suggested by...