The outputs of all these rectifier circuits contains some ripple factor. We have also observed that the ripple factor of a half wave rectifier is greater than that of a full wave rectifier. The ripple in the signal denotes the presence of some AC component. This ac component has to be completely removed in order to get pure dc output. So, we need a circuit that smoothens the rectified output into a pure dc signal. A filter circuit is one which removes the ac component present in the rectified output and allows the dc component to reach the load.
A filter circuit is constructed using two main components, inductor and capacitor. We have already studied in Basic Electronics tutorial that. As an inductor allows dc and blocks ac, a filter called Series Inductor Filter can be constructed by connecting the inductor in series, between the rectifier and the load. The figure below shows the circuit of a series inductor filter. The rectified output when passed through this filter, the inductor blocks the ac components that are present in the signal, in order to provide a pure dc.
This is a simple primary filter. As a capacitor allows ac through it and blocks dc, a filter called Shunt Capacitor Filter can be constructed using a capacitor, connected in shunt, as shown in the following figure.
The rectified output when passed through this filter, the ac components present in the signal are grounded through the capacitor which allows ac components. About us Contatti. Facebook Twitter YouTube. Donaldson PDF catalogues. Donaldson catalogues. Agricultural Catalogue. Bobcat Vehicle Card.
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It can easily filter a high-frequency signal but it cannot process any low frequencies. Although its design is simple but connecting a load to this filter impacts on its characteristics.
Cascading the passive filters for higher order filter affects the characteristics of the filter. The downside is that it needs an external source of power, but it provides a high voltage gain. This gain is used for amplifying any weak input signals.
The active filter can filter very low-frequency signals but it cannot process very high-frequency signal. That is why; the load impedance does not affect the characteristics of the active filters.
The filters are classified based on the frequency response into the following four categories. Low Pass filter allow low-frequency signals without any attenuation decrease in power but it rejects any high-frequency signals. The low pass filter has a reactive component, whose reactance varies with the input frequency. The variation in the reactance causes the voltage drop to increase or decrease inside the circuit. Any frequency less than the cutoff frequency is passed without any attenuation.
While any other higher frequency signal then the cutoff frequency will be blocked. Any signal with a frequency lower than the cutoff frequency of the filter gets blocked. While any signal with a frequency higher than the cutoff frequency passes with full amplitude. This type of filter has two cutoff frequencies i. Any input signal having frequency belonging to the passband frequencies will get passed without any attenuation.
This type of filter attenuates the signal whose frequencies lies in a fixed band of frequencies. It is also known as Band Stop filter or Notch Filter.
It works completely opposite to the bandpass filter. But it does not allow a fixed band of frequencies in between.
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