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.
The gain of this amplifier depends on the component values as well as the operating range and the...
This biestable vox circuit was found in an old documentation. The circuit makes use of components of...
This circuit is from 2001 documentation with the purpose of controlling a pump that fills a water...