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.
With this circuit published in Radio Electronics magazine in September 1959, it is possible to use a...
This variable bandpass filter was found in an American 1980s documentation. The power supply must be...
A four-bit analog-to-digital converter [A/ D or ADC] can be built using one 4066. An 8-bit...