This filter was found in a Texas Instruments manual based on an operational amplifier 741. Other operational can be used and, with the indicated components, the rejection frequency is 2 kHz.
This is a possible setting for a Colpitts oscillator operating in the audio track. The shunt coil...
With this circuit, three LEDs of different colors can be controlled sequentially. Adjustments of...
We found this circuit in an old English publication. The resistor not indicated can be 2k2 and the...