This 3-transistor buzzer or buzzer is a classic type found in the July 1998 issue of Electronics Now magazine. The power rating depends on the output transistor.
If the battery is good, the LED flashes. This simple tester uses an LM3909 integrated circuit. We found...
This circuit is from an old publication by A. Fanzeres. To use a unit, it is sometimes necessary to...
An interesting type of sensor for specific applications is the sensor formed by piezoelectric...