Selectable bandwidth notch filter

This circuit features adjustable bandwidth with a center frequency of approximately 800 Hz. A 10 kΩ potentiometer is used to adjust the bandwidth, varying from approximately ±350 Hz to ±140 Hz at the 3 dB down points. The circuit operates...

This narrowband filter utilizing the 741 operational amplifier can achieve a rejection level of up to 60 dB. By employing resistors with a value of 100 K ohms and capacitors of 320 pF, the circuit effectively rejects frequencies at...

The RF amplifiers utilize noiseless feedback through the drain-gate capacitance, incorporating an inductor in the source lead to achieve the necessary 90-degree phase shift between the gate voltage and channel current. The first RF amplifier provides approximately 4 dB...

This nonlinear, passive filter circuit rejects ripple (or unwanted but fairly steady-voltage) without appreciably affecting the rise time of a signal. The circuit works best when the signal level is considerably lower than the unwanted ripple, provided the ripple...

This circuit will filter out interference signals and ensure that the signal received from the Morse code station stands out. The described circuit functions as a signal processing system specifically designed to enhance the clarity of Morse code transmissions by...

A twin-T network is connected to an LM102 to create a high-Q, 60 Hz notch filter. The junction of R3 and C3, typically grounded, is bootstrapped to the follower's output. The low impedance of the follower ensures that neither...