Indicated for activation by microcontrollers, this circuit was found in the Radio Electronics magazine of December 1987. The MOSFET can be of any type according to the buzzer.
We found this circuit in a 1998 documentation. It senses the passage of people or objects through an...
This circuit is from a Linear datasheet. The circuit provides a 5 m voltage with 40 mA from an AA...
We found this circuit in a 1995 paper. The reed switches are surrounded by a few coils of coarse...