This circuit was published in an article in Radio Electronics magazine in October 1988. It uses components that are still common today, except for the sensor, which is a special type from that time.
This circuit is from the time when cars used contact breakers. This 80's version measures the dwell...
In the fist circuit the alarm triggers on when any sensor is CUT. In the second circuit the alarm...
We found this Vox in a 1969 Motorola documentation. Transistors support modern equivalents and the SCR can...