AC Tachometer (CB9353E)

This circuit was found in a 1969 EEE. It detects when there is a phase failure in a circuit using an inductive sensor.

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Flood Alarm (CB12183E)
This circuit activates a relay when the water reaches the sensors. The circuit is from a magazine...
White Noise Generator (CB412E)
The noise comes from the PN junction of a common silicon diode. Since no gain is given by the...
Audio Preamplifier (CB16297E)
We have here an interesting audio preamplifier, which can be useful to those who are looking to...