 In today's session, we are going to see one of the basic applications of pain junction diode, diode clipper circuits. At the end of this session, students will be able to explain basic types of diode clipper circuits and describe operation of different clipper circuits. These are the contents of my presentation. Now students should pause the video here for some time and recall how pain junction diode works as electronic switch. When anode of diode is at higher potential with respect to cathode by minimum voltage of barrier potential of pain junction diode, diode conducts, acts as a short circuit from anode to cathode and operates as an on switch. When voltage at anode is lower than the voltage at cathode, diode does not conducts, acts as an open circuit from anode to cathode, diode operates as off switch, diode clipper circuits. Let us define clipper circuit, clipper circuit is an electronic circuit which clips off certain part of input AC voltage signal waveform above or below certain reference level without changing remaining part of input AC voltage signal waveform and its frequency. Design components, diode clipper circuit can be designed using diode as an electronic switch and resistor and DC voltage source. resistor is current limiting resistor, it limits the amount of current flowing through on switch diode and DC voltage source is used to set desired DC reference level that is clipping level. Clipper circuits are also known as DC limiting circuits, DC limiters because output signal voltage waveform is limited to certain DC voltage level after clipping operation. So, diode clippers are used for wave shipping in wave shaping circuits and wave shaping circuits are commonly used in various electronics systems like radar system, television system, radio system, computer system, etc. Now, let us classify the clipper circuits, basically clipper circuits are categorized as positive clipper, negative clipper, biased clipper and combinational clipper. Let us start with the first type of clipper circuit that is simple positive clipper circuit. Diode positive clipper circuit either series or shunt clipper circuit removes input AC voltage signal waveform above zero reference level that is positive part of input AC voltage signal waveform is removed. Consider figure 1.1 it is a positive shunt or parallel clipper circuit in which diode is connected in parallel or shunt with input and output. Figure 1.2 is a positive series clipper in this diode is connected in series with input signal source. Positive clipper clips off positive part of input signal and all negative part remains same. Now, let us analyze working of this positive clipper circuit assuming diode is ideal that is voltage drop Vd across conducting diode is zero volt that is barrier potential of diode is zero volt. Consider figure 1.1 that is positive shunt parallel or parallel clipper when input is positive that is input voltage Vi is greater than zero volt then diode is start on starts conducting acts as a short circuit from anode to cathode so voltage across diode Vd is zero volt so output voltage is equal to zero volt so in this way positive part of input signal is clipped off removed at the output when input voltage is less than zero volt that is when input signal is negative then diode is turn off does not conduct acts as a open circuit from anode to cathode. So output voltage is equal to the input voltage Vi output voltage is exactly same as the input voltage output voltage follows the input voltage so thus positive clipper simple positive clipper clips off a positive part of input AC voltage signal waveform now let us go for second type of basic clipper circuit negative clipper simple negative clipper series or shunt clipper removes input AC voltage signal waveform below zero reference level that is negative part of input AC voltage signal waveform is clipped off. Using idle diode let us analyze working of negative clipper consider figure 2.2 that is negative shunt clipper diode is connected in shunt or parallel with input and output when input voltage signal waveform is above zero volt reference level that is when input is positive then diode is turn off it does not conduct acts as a open circuit so output voltage V o is equal to input voltage Vi so output voltage follows the input voltage when input voltage becomes negative less than that is less than zero volt then diode is turned on acts as a short circuit so output voltage is equal to zero volt since the voltage across connecting diode is zero so in this way so negative part of input AC voltage signal waveform is clipped off or removed now let us go for third type of clipper circuit that is biased clipper in biased clippers DC voltage source like battery is connected in series with a diode is used to set desired DC reference level clipping level sometimes it is required to clip off input AC voltage signal waveform above or below certain positive or negative at DC voltage level so in that case biased clippers circuit is used figure 3.1 is biased positive clipper and figure 3.2 is biased negative clipper consider figure 3.1 when input voltage Vi is less than a DC voltage V that is connected in series with diode then diode does not conduct it remains off acts as a open circuit from anode to cathode as long as input voltage is less than a DC voltage V diode remains off so DC voltage V is disconnected from output line so output voltage follows the input voltage so output voltage is equal to the input voltage when input voltage just exits the DC voltage connected in series with diode that is when Vi is greater than V then diode is turned on acts as a short circuit from anode to cathode so DC voltage V is connected to the output line so output voltage is limited restricted equals a DC voltage V so as long as input AC voltage signal waveform is greater than DC voltage V output remains at equals to a DC voltage level V so in this way the input signal voltage waveform above DC voltage level V is clipped off again when the input voltage falls below the DC voltage V again diode is turned off and output voltage follows the input voltage figure 3.2 is biased negative clipper so this clips off some part of negative half cycle of input AC voltage signal waveform below the negative clipping level or reference level V now next final type of a clipper circuit is a combinational clipper circuit the combinational clipper circuit is the combination of biased positive clipper and biased negative clipper with the use of DC voltages V1 and V2 to set clipping levels the clipper removes AC voltage signal waveform above or below a DC voltage level V1 and V2 now consider figure 4 that is combinational clipper the two diodes D1 and D2 are connected in parallel to input and output with DC voltages V1 and V2 are connected in series with the two diodes D1 and D2 when input voltage is less than V1 and greater than V2 that is input signal voltage is in between the voltage level V1 and V2 both diodes does not conduct remains off acts as a open circuit so DC voltages V1 and V2 are disconnected from output line so output voltage follows the input voltage output voltage is exactly same as input voltage so V1 is equal to VI when input voltage becomes greater than V1 then diode D1 is turned on acts as a short circuit and DC voltage V1 is connected with output line and output voltage is equal to a DC voltage V1 when input voltage VI becomes less than V2 diode D2 is turned on and D1 remains off so output voltage is equal to the DC voltage V2 as long as the input voltage is less than V2 output voltage is limited to a DC voltage level V2 so the signal voltage below DC voltage level V2 is clipped off these are the references thank you