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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Pulse motor control (CB20554E)
This circuit was found in the PC documentation from 1996. The maximum current of the motor is...
Audio generator with the 741 (CB24106E)
This circuit is from the time when the 741 was first introduced. It was published in the February 1971...
General Purpose Audio Preamplifier (CB15656E)
Only two transistors are used in this preamp for low-sensitive transducers, such as guitar and...