This capacitive sensor that operates with a high frequency oscillator was found in Radio Electronics from the 90's. The circuit operates around 300 kHz.
This circuit is from a Linear Technology integrated circuit manual from the 1990s. The circuit...
The IC used in this project is not common these days, but if you have one you can build a high...
With this circuit, it is possible to excite a white LED or another type of high brightness with...