This circuit was found in a British documentation from 1969. It can be implemented with modern transistors. The pass band is 6 MHz.
This circuit warms a light bulb slightly so that the wind through it alters the filament...
This circuit is based on the Linear Technology LT1495 and was found in a 2005 manual. The circuit...
The circuit illustrated in the figure can be used to detect earthquakes or vibrations of...