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.
We have already presented this circuit elsewhere on our website. This version of an English...
With this circuit it is possible to obtain an intermediate voltage of 6 V from a 12 V battery with...
This 9 V battery eliminator was found in Radio Electronics magazine from June 1966. The transistor is of...