Refrigerator Monitor (CB26012E)

This circuit that detects when the refrigerator is not working properly was found in the February 1997 Electronics Now magazine.

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Stable voltmeter (CB23664E)
This sensitive two-transistor circuit was found in the June 1965 Radio Electronics magazine. The...
Remote Phone Ring (CB1349E )
This circuit, obtained in an old publication, causes a second telephone bell to be played in a...
Neon high voltage regulator (CB8804E)
Found in a1969’s neon lamp documentation, this circuit uses a high voltage transistor. The output...