Power Failure Alarm (CB25348E)

This circuit triggers an alarm when the mains power is cut off. The circuit was found in the July 1990 issue of Radio Electronics magazine.

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Guitar preamp (CB22146E) Found in an English publication from 1989, this circuit uses a still common operational amplifier. The power supply does not have to be symmetrical. a href="images/stories/bc/04291029"
Guitar preamp (CB22146E) Found in an English publication from 1989, this circuit uses a still...