Telephone Off-Hook Alarm (CB24903E)

This circuit for old telephones was found in July 1985 Radio Electronics magazine. It activates an alarm if the telephone is left off the hook.

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Multitester (CB17090E)
This sensitive multi-circuit and component prover uses two transistors and has a switch position where...
Action Video Game (CB24648E)
This video game is another of the AY3 series with the AY3-3606 integrated circuit. The circuit was found...
Two transistors power stage (CB23532E)
This power stage with two transistors was found in Radio Electronics magazine from October 1963....