This filter was found in an 80's English publication. However, it can be implemented with modern operating systems. The circuit can tune frequencies in a range from 10,000 to 1.
This siren circuit was found in 1987. The components are common, and power is provided by standard...
This circuit was found in specialized microwave documentation from the 1960s. The circuit makes use...
Found in Popular Electronics from the 90s, this circuit powers a warning lamp when the load is...