This circuit found in the February 1992 issue of Radio Electronics magazine is designed to adapt an audio signal for use in a computer's ADC. It can be adapted to operate with microcontrollers.
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...
In the figure we have a circuit that uses unusual components, being indicated for low frequency...
The sensor of this circuit found in Popular Electronics can be formed by a piece of fabric between two...