This circuit was published in the July 1993 issue of Electronics Now magazine. It uses a sensor from the time and triggers a buzzer with a Sonalert-type oscillator.
The circuit shown consists of a simple tester for general purpose silicon or germanium diodes and...
This circuit was published in an English magazine from 1972, but it can be easily implemented...
This automotive alarm uses common components and is suitable for old vehicles. The circuit was...