Phone Patch (CB9398E)

This circuit was found in a 1969 CQ magazine. It is intended for coupling telephones to radio amateur equipment

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Two-tone decoder (CB8719E)
Found in a 90s 73 magazine, this circuit uses an unusual component today which is the XR2206. |...
Noise generator (CB23830E)
This random noise or white noise generator was published in Radio Electronics magazine in July...
Low current in the dark light sensor (CB8311E)
This circuit was found in Philips documentation from 1967. The phototransistor is from that time,...