Found in Radio Electronics from the 90s, this siren finds many variations on this site. The transistor must be equipped with a heat radiator.
This circuit converts a high impedance signal into low impedance. The circuit has unit gain and...
This project came out in an article of mine (Newton C. Braga) in the Popular Electronics magazine of...
This variable oscillator with crystal was found in a Popular Electronics of the 90s. The circuit uses...