This circuit was found in a Hands On Electronics from the 80's. The circuit emits an audible alert when dawn and the sensor receives solar illumination.
This variable oscillator with crystal was found in a Popular Electronics of the 90s. The circuit uses...
This fuzz effect for guitars was found in an American 1980s documentation. The transistors may be the BC549...
The oscillator shown in the figure emits sound when or another input is taken to a high level and...