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 circuit monitors the voltage of a 12 V battery. The indicated levels let you know if the...
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even...