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 two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The...
This blocking oscillator was found in a publication from the 50's. The coils determine the...
The TPA3100D2 integrated circuit from Texas Instruments (www.ti.com) consists of an efficient...