Found in the February 1983 Radio Electronics magazine, this circuit uses a FET and has good gain at the frequencies determined by the components. The FET is any general-purpose FET.
Vishay's VCNL4200 integrated circuit consists of a fully integrated proximity detector containing...
This circuit samples the current in a load and in case of excessive value it activates a...
The frequency of this oscillator depends on the crystal used and the transistors. The circuit was...