Diode Based Circuits



Case Study



Aim:


To design and simulate a Half Wave Rectifier circuit.

Components required:


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


Vlab Specifications Taken:


Half 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. During the positive half cycle, the diode is forward biased and it conducts and hence a current flow through the load resistor. During the negative half cycle, the diode is reverse biased and it is equivalent to an open circuit, hence the current through the load resistance is zero. Thus the diode conducts only for one half cycle and results in half wave rectification. The input and output voltage waveform may be analytically written as:

and
where
and Vt is cut-in voltage of the diode.

Circuit Diagram

The average (dc) value of half 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
  • Ripple Factor

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

  • Efficiency
  • Efficiency, eta is the ratio of the dc output power to ac input power:

  • Form Factor
  • Form Factor is given by,

  • Peak Factor
  • Peak Factor is given by,



    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.
      2. 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: 1.91V






    Calculations:



    From the Output waveform the following parameters has been observed whcih can be used for the calculations below:
    1. output waveform frequency =1KHz
    2. Oupur Voltage Vpl = 1.91V
    3. Vrms = Vpl/2 = 0.955V
    4. Vdc = Vpl/pi = 0.608V
    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,

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

      Experimentally,

    5. Form Factor
    6. Form Factor is given by,

      Experimentally,

    7. Peak Factor
    8. Peak Factor is given by,

      Experimentally,



      Result:


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