Full Wave Rectifier With and Without Filters
Objective:
To study the operation of Full Wave Rectifier with and without filter and to find its:
 Percentage Regulation
 Ripple Factor
 Efficiency
Components:
S.No.  Name  Quantity 

1  Bread board  1 (One) No. 
2  Diodes (1N4007)  2 (Two) No. 
3  Resistor (1K)  1 (One) No. 
4  Capacitor (1000F)  1 (One) No. 
Equipment:
S.No.  Name  Quantity 

1  Transformer with Center Tapped Secondary ( 9  0  9 )V  1 (One) No. 
2  Digital Multimeter  1 (One) No. 
3  Cathode Ray Oscilloscope (CRO) (020MHz)  1 (One) No. 
4  Connecting wires (Single Strand) 
Operation:
The conversion of AC into pulsating DC is called Rectification. Electronic Devices can convert AC power into DC power with high efficiency.
The fullwave rectifier consists of a centertapped transformer, which results in equal voltages above and below the centertap. During the positive half cycle, a positive voltage appears at the anode of D1 while a negative voltage appears at the anode of D2. Due to this diode D1 is forward biased. It results a current Id1 through the load R.
During the negative half cycle, a positive voltage appears at the anode of D2 and hence it is forward biased, resulting a current Id2 through the load. At the same instant a negative voltage appears at the anode of D1, reverse biasing it and hence it doesn’t conduct.
Ripple Factor:
Ripple factor is defined as the ratio of the effective value of AC components to the average DC value. It is denoted by the symbol ''.
Rectification Factor:
The ratio of output DC power to input AC power is defined as efficiency.
= 81% (if R >> R_{f}, then R_{f} can be neglected).
Percentage of Regulation:
It is a measure of the variation of DC output voltage as a function of DC output current (i.e., variation in load).
Percentage of regulation = %
V_{NL} = Voltage across load resistance, when minimum current flows through it.
V_{FL} = Voltage across load resistance, when maximum current flows through.
For an ideal Fullwave rectifier, the percentage regulation is 0 percent. The percentage of regulation is very small for a practical full wave rectifier.
Peak Inverse  Voltage (PIV):
It is the maximum voltage that the diode has to withstand when it is reverse biased.
PIV = 2V_{m}
Advantages of Full wave Rectifier:
 is reduced.
 is improved.
Disadvantages of Full wave Rectifier:
 Output voltage is half of the full secondary voltage.
 Diodes with high PIV rating are to be used.
 Manufacturing of the centertapped transformer is quite expensive and so Full wave rectifier with centertapped transformer is costly.
Circuit Diagram:
Full Wave Rectifier (without filter):
Full Wave Rectifier (with filter):
Procedure:
 Connect the circuit as shown in the circuit diagram.
 Connect the primary side of the transformer to AC mains and the secondary side to rectifier input.
 Using a CRO, measure the maximum voltage V_{m} of the AC input voltage of the rectifier and AC voltage at the output of the rectifier.
 Using a DC voltmeter, measure the DC voltage at the load resistance.
 Observe the Waveforms at the secondary windings of transformer and across load resistance for a load of 1K.
 Calculate the ripple factor (), percentage of regulation and efficiency () as per the below given formulae.
Observations:
 Peak Voltage, V_{m} = (From CRO for HWR with and without filter)
 DC Voltage, V_{DC(full load)} = (From Voltmeter/ Multimeter for HWR with and without filter)
 No Load DC Voltage, V_{DC(No load)} = (From Voltmeter/ Multimeter for HWR with and without filter)
 Ripple Voltage, V_{r} = (From CRO for HWR with filter)
Calculations:
Without filter:
Ripple factor (Theoretical) =
Ripple Factor (Practical)
With filter:
Ripple factor (Theoretical)
Where f = 50Hz, R =1K, C = 1000F.
Ripple Factor
Percentage Regulation = %
V_{NL} = DC voltage at the load without connecting the load (Minimum current).
V_{FL} = DC voltage at the load with load connected.
Efficiency %u200B
P_{AC} = V^{2}_{rms} / R_{L}
P_{DC} = V_{dc} / R_{L}
Expected Waveforms:
Result:
The operation of Full Wave rectifier is studied and the following are calculated.
Type of Rectifier  Ripple factor  Efficiency  % Regulation  
Theoretical  Practical  
FWR without filter  
FWR with filter 
Outcomes: Students are able to
 analyze the operation of Full Wave rectifier with and without filter.
 calculate its performance parametersripple factor, percentage regulation, efficiency with and without filter.
Viva Questions:
1. What is filter?
Ans: Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal.
2. Give some rectifications technologies?
Ans: Synchronous rectifier, Vibrator, Motorgenerator set , Electrolytic ,Mercury arc, and Argon gas electron tube.
3. What is the efficiency of bridge rectifier?
Ans: %
4. What is the value of PIV of a center tapped FWR?
Ans: 2V_{m.}
5. In filters capacitor is always connected in parallel, why?
Ans: Capacitor allows AC and blocks DC signal.in rectifier for converting AC to DC, capacitor placed in parallel with output, where output is capacitor blocked voltage.If capacitance value increases its capacity also increases which increases efficiency of rectifier.
6. What is the purpose of Center Tapped transformer?
Ans: Center tapped transformer in FWR produce the voltages are in phase with each other,we can produce the current in only one direction.It reduces the voltage drop across the load.
7. What is Regulation?
Ans:Line regulation is the ability to maintain specified output voltage over changes in the input line voltage.
Load regulation is the ability to maintain specified output voltage given changes in the load.
8. What is the location of poles of filter in Splane?
Ans:The Splane is a complex plane with an imaginary and real axis referring to the complexvalued variable z. The position on the complex plane is given
by re^{iθ} and the angle from the positive, real axis around the plane is denoted by θ. When mapping poles and zeros onto the plane, poles are denoted by an
"x" zeros are denoted by"o".
(image from http://pilot.cnxproject.org)
9. What is the output of FWR with filter? Is it unidirectional?
Ans: FWR with filter output is
It is unidirectional output.
10. What are the advantages and disadvantages of center tapped fullwave rectifiers compared with Bridge rectifiers?
Ans:
Center tapped FWR  Bridge Recticfier 
One diode conducts in each half cycle of input  Two diodes conduct in each half cycle of input 
The output voltage is more  The output voltage is less 
PIV rating of the diode is 2V_{sm}  PIV rating of the diode is V_{sm} 
The transformer is less effectively used T.U.F is 0.693.  The transformer is more effectively used T.U.F is 0.812. 
11. Define Ripple factor ‘γ’ and its values for the three types of rectifiers.
Ans:Ripple factor can be defined as the variation of the amplitude of DC (Direct current) due to improper filtering of AC power supply. it can be measured by RF = v_{rms} / v_{dc}
Ripple factor for Half wave recifier is 1.21, FWR is 0.482 and Bridge recifier is 0.482
12. What is the value of No load voltage for all the three types of the rectifiers?
Ans: For HWR V_{NL} is V_{sm}/ , For FWR V_{NL} is (2V_{sm })/ and For bridge rectifier is (2V_{sm })/
13. What are the different types of filters used for the rectifiers?
Ans:Capacitor filter, Inductor filter, LC filter and CLC() filter .

UpdatedOct 31, 2019

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