Diode Based Circuits



Case Study



Aim:


To design and simulate a Full Wave Rectifier circuit.

Components required:


   Function generator, CRO, Regulated Power supply, resistor, diode, connecting wires.


Vlab Specifications Taken:


Full wave circuit design has been implemented on the virtual breadboard using following specifications:

  • Power Supply: +10v and -10v
  • Function generator: Selected wave with following specifications:
Frequency = 1KHz.
Amplitude: 5V
Duty cycle = 50%
  • Resistor R1: 10.36K



Theory:


The conversion of AC into DC is called Rectification. Electronic devices can convert AC power into DC power with high efficiency. A drawing of a full-wave bridge rectifier is given below. The bridge is composed of four diodes in a diamond shape. During the positive half-cycle of input voltage vin the terminal A is at positive potential with respect to the terminal B and because if this diodes D1 and D2 are forward biased whereas diodes D3 and D4 are reverse biased. The current therefore flows through diodes D1, D2 and load resistor RL. During the negative half-cycle of input voltage waveform, on the other hand, the diodes D3 and D4 are forward biased whereas the diodes D1 and D2 are reverse biased. As a consequence, current flows through diodes D3 and D4. The input and output voltage waveform may be analytically written as:

and
where

Circuit Diagram

The average (dc) value of full wave rectified sine wave voltage is represented by
RMS voltage at the load resistance can be calculated as


Procedure:


  1. Connect the circuit as shown in the circuit diagram.
  2. Give the input signal as specified.
  3. Switch on the power supply.
  4. Note down the value of AC and DC voltages from the CRO
  5. Draw the necessary waveforms on the graph sheet.


Observations:


  1. Observe the output waveform from CRO.
  2. Measure the value of AC and DC voltages of the output waveform from the CRO.
  3. Calculate
    1. Ripple Factor

      2. Ripple factor is defined as the ratio of effective value of AC component to the average DC value.
      Ripple Factor (r),

    2. Efficiency
      3. Efficiency, eta is the ratio of the dc output power to ac input power:

      The maximum efficiency of a Full Wave Rectifier is 81.2%.
    3. Form Factor
      4. Form factor is defined as the ratio of the RMS value of the output voltage to the average value of the output voltage.

    4. Peak Factor
      5. Peak factor is defined as the ratio of the peak value of the output voltage to the rms value of the output voltage.



VLab Observations Obtained:


    1. After Clicking on Open function generator icon on the left of the Vlab live environment page, set the frequency, amplitude and the type of waveform on function generator.
    1. Select sine wave and then set frequency 1KHz



    1. Set the peak to peak voltage Vpp = 5v i.e. amplitude = 5v.




    1. Check graph



    1. Circuit has been designed on the virtual breadboard with the help of procedure.



    1. Then on clicking on Run icon, the output waveform generated and the input can be observed on the CRO. CRO web page can be opened using icon oscilloscope at top left on the live experiment page.




    1. Click on measure.Then one can observe options like source, select, measure.


      • Click on source and select 1 i.e. the output wave.


      • Click on select and select the parameter to be measured for example select frequency or amplitude.


      • Click on measure to get the frequency and amplitude of the output waveform.

      It comes out to be Frequency: 1KHz, amplitude: 1.02V






Calculations:



From the Output waveform, the following parameters can be obsereved which can be used for calculations below:
    1. output waveform frequency =1KHz
    2. Oupur Voltage Vpl = 1.02V
    3. Vrms = Vpl/squareroot2 = 0.721V
    4. Vdc = 2Vpl/pi = 0.649V
  1. Ripple Factor

    2. Ripple factor is defined as the ratio of effective value of AC component to the average DC value.
    Ripple Factor (r),

    Experimentally,

  2. Efficiency
    3. Efficiency, eta is the ratio of the dc output power to ac input power:

    Experimentally,

  3. Form Factor
    4. Form Factor is given by,

    Experimentally,

  4. Peak Factor
    5. Peak Factor is given by,

    Experimentally,



    Result:


    The Full Wave Rectifier circuit design output waveforms have been studied and the required parameters are calculated.

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