This circuit was obtained from an 80's Radio Electronics. The circuit decodes “scrambled” or sinusoidal encoded signals by providing an audio signal at the output.
This circuit can be used to test continuity or even semiconductors. We found the configuration in a 1987...
This circuit serves as a reference for the components used and the time. The circuit is from 1967...
The integrated circuit used in this filter is not very common today, but the configuration can be implemented...