 Hello everyone. Welcome to this video lecture. Myself Deepali Vardhakar, working as assistant professor at WIT Solapur. In this video lecture, we will study filter circuits. At the end of this video lecture, student will be able to illustrate working of filter circuit. Student will be able to illustrate the working of half wire rectifier with capacitor filter. Student will be able to illustrate the working of full wire rectifier with capacitor filter. The filter, it is the one which removes the AC component present in a rectifier output and allows the DC component to reach the load. So, the basic working of filter that is to remove the AC component from the input and allows only DC component at the output. There are different types of filter like capacitor filter, fire filter, choke filter. So, out of that in this video lecture, we will study shunt capacitor filter. Here the capacitor is placed across the load. The rectifier output is given input to the capacitor filter and this will be the output at the capacitor filter. The capacitor offers infinite reactance to DC because the DC having zero frequency. So, reactance of capacitance is equal to 1 upon 2 pi fc which is equal to 1 upon 2 pi into frequency 0 into capacitance which is equal to infinite. Hence, the capacitor does not allow DC to pass through it. So, before going to capacitor filter, let us see the working of capacitor. So, when we connect the key in position A, then this power supply is get connected to this capacitor and both the plates of this capacitor get the equal and opposite charges that is plus q and minus q and the potential difference vc start increasing while the capacitor is charging. Once the voltage at the terminal of capacitor vc is equal to the supply voltage that is v is equal to vc, then the capacitor is fully charged and the current stop flowing through the circuit. This completes the charging phase. Now, let us see the discharging process of capacitor. In the next step, when we replace the key from position A to position B the capacitor will start discharging. When key is connected to position B, bulk will glow. Intensity of bulk and voltage between the capacitor plates drops down gradually to zero which completes the discharging. Now, let us see the rectifier circuit with capacitor. So, first that is the half-way rectifier with capacitor filter. So, we know that half-way rectifier consists input AC source diode. In the half-way rectifier with capacitor filter the capacitor is placed across the load resistance REL and it is placed across the rectifier circuit. So, let us see the working of half-way rectifier with capacitor filter. During the positive half-cycle of input AC signal the initial at the initial condition the voltage across the capacitor that is the vc is assumed to be zero. So, whenever the positive half-cycle of input AC signal then the vc is less than vin. So, this capacitor starts charging. This capacitor charges up to peak voltage that is up to 0.7 volt. Once the voltage across the capacitor vc is becomes equal to the input voltage vin then capacitor starts to stop at that point the capacitor stops charging. When input voltage starts decreasing that is when vin starts decreasing then the diode becomes reverse bias and this capacitor starts discharging because here voltage across capacitor vc becomes greater than vin. So, this capacitor starts discharging through this load REL. So, these are the input output characteristics. The input sinusoidal voltage this is the charging and discharging of capacitor. When diode is forward bias the capacitor charges. When diode is in reverse bias the capacitor discharges. Again this discharges up to next positive half-cycle of rectifier input. Now next center tap full-way rectifier with capacitor field. Center tap rectifier consists center tap transformer. Here two diodes use diode D1 and diode D2 both are connected to the load REL. So, changes here that is the capacitor is placed across this load REL. In the positive half-cycle of input AC diode D1 becomes forward bias and diode D2 is in reverse bias. So, diode D1 act as a closed switch, diode D2 act as a open switch. So, diode D1 conduct the current which charge this capacitor. So, in the positive half-cycle the capacitors start charging. Now these capacitors charge up to peak value of this input. After the peak value as the input voltage start decreasing then this diode becomes reverse bias and the voltage across capacitor is greater than the input voltage. So, these capacitors start discharging. In negative half-cycle the diode D1 becomes reverse bias and diode D2 is in forward bias. So, diode D2 conducts in the negative half-cycle. So, the current charging current of this capacitor flows through this diode D2. So, again here capacitor charges up to positive peak value. Once this reverse voltage start decreasing input voltage then the voltage across capacitor becomes greater than input voltage and capacitor again start discharging. So, in the positive as well as negative half-cycle of input AC signal here charging and discharging of capacitor takes place. Now, next that is the bridge-fullway rectifier with capacitor filter. So, in the bridge-fullway rectifier 4 diodes use D1, D2, D3 and D4. All these diodes are connected in bridge configuration that is in closed loop. Across these two terminals input AC signal is connected across these two terminals load is connected. So, in capacitor filter with bridge-fullway rectifier the capacitor is connected across the load resistance RL. So, we know that working of full-way rectifier during the positive half-cycle diode D1 and diode D2 becomes forward bias and hence the current flows through the load and through the diode D1 and D2. And during the negative half-cycle diode D1 and D2 both are in reverse bias and D3 and D4 are in forward bias. So, during the negative half-cycle of input AC signal D3 and D4 diodes conducts the current through the load. So, here the capacitor is connected across the load. So, whenever the positive half-cycle of input AC signal at that time D1 and D2 becomes forward bias and the current flows through the D1 and D2. So, which is shown here. So, whenever the positive half-cycle of this rectifier the capacitors start charging. This capacitor charge up to positive peak. After that the voltage across capacitor becomes greater than input voltage. So, as the rectifier output decreases the input voltage also input voltage to the capacitor filter also decreases. So, this capacitor start discharging. This capacitor discharge up to next positive half-cycle. So, in this way charging and discharging voltage present across this capacitor and hence across the load. So, these are the waveforms without the capacitor filter and these are the waveforms with the capacitor filter. So, most of the ripples get removed due to this capacitor filter. Now question which rectifier having more efficiency. So, we have studied the half-wave rectifier as well as full wave rectifier working with capacitor filter. So, from the observation explain which rectifier having more efficiency. Pause the video for a while and think. Okay. So, in half-wave rectifier this is the charging and discharging waveforms of the capacitor rectifier. These are the charging, discharging of capacitor. Okay. So, from this we observe that the half-wave, full wave rectifier having more efficiency than the half-wave rectifier. So, more ripples are get removed by using full wave rectifier with capacitor filter. So, it is more efficient than the half-wave rectifier with capacitor filter. So, these are the references. Thank you.