This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even adapted to act as a shield. The circuit has the frequency given by C1 and adjusted in R1.
This configuration enables the use of low current switches or sensors to control high power loads...
This circuit is from an April 1988 Radio Electronics magazine. The circuit is retriggerable and...
Mouser Electronics is offering the new INA3221 integrated circuit consisting of an amplifier for...