Power frequency noise filter PC822 schematic

Posted on Mar 28, 2007

As shown in FIG frequency power supply noise filter circuit. The circuit is a double-T filter, can be used to amplify (such as sensors) weak signal, to mixed 50Hz (or 60Hz) pow

Power frequency noise filter PC822 schematic
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er supply frequency noise will be filtered out. If using only the RC element composed of such filter, the Q value is generally low, and the attenuation characteristic having broadband characteristics. Using op amps and add positive feedback can improve the Q value. Let Q value at this time is Q, then Q Q/(1 a K), where, K RA/(RA + RB). Changing the coefficient K can make Q value increases. The resonant frequency of the circuit is fo 1/2 RC, positive feedback element of R/2 and 2C. Taking into account the characteristics of using a capacitive decentralization, the resonant frequency to be set lower, then the potentiometer PR1 and PR2 to adjust the frequency to 50Hz (or 60Hz). When adjusting the input 50Hz (or 60Hz) sinusoidal voltage, filter it through PR adjust the output voltage to a minimum. With this filter, if the input power supply noise is not a sine wave, there will be a high-frequency component by the filter. AC power is generally higher harmonics 3,5,7 and other odd harmonics can be filtered by low-pass filter access to these harmonics.

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