This circuit was found in a Popular Electronics of the 1990s. The sensor is a rotating mechanical system with a propeller-driven magnet to count pulses with a reedswitch.
This timebase was found in a European 1980s documentation. The circuit uses well-known components...
This circuit was obtained in an old US 1974 documentation when Nixie tube displays were common. The...
This circuit generates low-frequency sinusoidal signals. The variable capacitor is dual and the...