This circuit was found in Radio Electronics from the 90s. It converts capacitance into frequency in order to obtain a proportional voltage that can be measured in a common multimeter.
This Motorola circuit uses only one transistor. The circuit is from 1965 documentation. The...
This circuit uses a piezoelectric transducer to produce sounds like a buzzer. Frequency is...
This circuit was suggested by General Electric in a 1965 documentation. The circuit can be...