Adjustable notch filter. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Radio amateur designer

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Robert Pease's adjustable notch filter (Fig. 22) allows you to remove unwanted components from the audio signal, for example, background with a mains frequency of 50 Hz.

Along with simplicity and the absence of inductors, the circuit has a number of unique properties - the rejection frequency controller R2 does not affect either the transmission coefficient K=R3/2R1 or the rejection bandwidth df=1/pCoR3. The rejection frequency itself is determined by the expression

Literature

1. "Electronics World incorporating' Wireless World" No. 2/2000, pp. 120-125.

Publication: N. Bolshakov, rf.atnn.ru

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