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.
For reference only, this is the first IF amplifier stage of a common transistor radio from the...
This oscillator employs a Motorola operational amplifier common in the 70s. We can implement the...
This circuit came out in a publication called Electronics Handbook of 1993. The circuit activates a...