This circuit was found in a 90s Popular Electronics. The integrated circuit used is uncommon today. The power is about of 2 W.
This circuit was found in Japanese documentation from the 1960s. It is a commercial circuit with...
This tone control was obtained in the Audio Handbook of the National Semiconductor of 1977. The...
This simple receiver for listening on the phone was obtained in a 1960 documentation. The circuit is...