Audible warning for answering machine (CB9295E)

Found in a Popular Electronics from the 90s, it applies to the old answering machines that used tapes. It emits a warning beep on the drive.

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2 transistor radio (CB20517E)
This circuit with germanium transistors was found in documentation from the 50's. The transistors are...
Old Phase Shift Oscillator (CB13956E)
The circuit presented was found in a documentation from the 1950s, generating a sinusoidal signal...
VHF Preamplifier (CB19599E)
This circuit was originally indicated as a signal reinforcement step for the previous receiver...