This circuit was obtained from an 80's EDN. The components used are still common. The circuit can be used as a shield and the frequency is approximately 775 Hz.
The integrated circuits in this application are not very common today. One consists of an A / D...
This CMOS oscillator circuit generates signals up to a few megahertz, depending on the capacitor value....
This circuit was found in a 1977 American manual. The integrated circuit is from the time....