This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay is 12 V. The circuit is from Radio Electronics magazine, April 1975.
Found in a Raytheon circuit manual from the 1960s, this circuit uses the CK722 and a...
With this circuit it is possible to measure RF signals with a common multimeter. Signals up to 200...
This circuit was found in a 1967 US publication. In it we have the implementation of a ring...