Volume expander amplifier (T364E)

This circuit was found in the 1961 RCA tube manual. The circuit includes a power supply stage.

Bicycle Speed Alarm (CB13735E)
This circuit was found in an American magazine in 1978. It activates a relay when the speed of a...
Salen Key Low Pass Filter (CB4865E)
This second-order low-pass Salen-Key filter was obtained from an American 1980s documentation. Formulas...
Siren with Touch Sensor (CB23790E)
The circuit shown in figure 1 generates an intermittent tone in a piezoelectric transducer when...