Practical - 26 :- To Construct And Test A Half-Wave Rectifier (HWR) And A Full-Wave Bridge Rectifier (FWR).

Aim :- To Construct And Test A Half-Wave Rectifier (HWR)

And A Full-Wave Bridge Rectifier (FWR).

🛠️ Components and Equipment

AC Power Source: A function generator (recommended) or a step-down transformer (e.g., 220V/12V or 110V/6V, depending on your region and components) to provide a low-voltage AC input.
Diodes: General-purpose rectifier diodes (e.g., 1N4001 or similar).
- HWR: 1 Diode
- FWR (Bridge): 4 Diodes
Load Resistor ( $\mathbf{R_L}$ ): A carbon film resistor (e.g., 1 k$\Omega$ or similar).
Capacitor (for filtering): An electrolytic capacitor (e.g., 100 $\mu$ F to 1000 $\mu$ F) to observe the smoothing effect.
Measurement Tools:
- Oscilloscope (CRO): Essential for viewing the AC input and pulsating DC output waveforms.
- Digital Multimeter (DMM): For measuring AC RMS voltage and DC average voltage.
Other: Breadboard, connecting wires.

Circuit Diagram: The circuit is a series connection of the AC source, a diode ( $\mathbf{D_1}$ ), and the load resistor ( $\mathbf{R_L}$ ).
Steps:
- Connect the AC source to the anode of the diode ( $\mathbf{D_1}$ ).
- Connect the cathode of the diode to one end of the load resistor ( $\mathbf{R_L}$ ). (The cathode is usually marked with a band/line).
- Connect the other end of $\mathbf{R_L}$ back to the other terminal of the AC source to complete the loop.

Input Waveform: Connect Channel 1 of the oscilloscope across the AC source terminals. Observe and record the waveform (a sine wave) and its measurements (Peak Voltage ( $\mathbf{V_{p,in}}$ ) and Frequency ( $\mathbf{f_{in}}$ ).
Output Waveform: Connect Channel 2 of the oscilloscope across the load resistor ( $\mathbf{R_L}$ ).
Observation: Observe and record the output waveform. You should see only the positive half-cycles of the input sine wave, with a slight drop in peak voltage due to the diode's forward voltage drop ( $\mathbf{V_{p,out} \approx V_{p,in} - 0.7V}$ for a silicon diode). The negative half-cycles should be clipped off (zero output).
Measurement: Use the DMM to measure the AC RMS voltage ( $\mathbf{V_{rms,out}}$ ) and DC Average voltage ( $\mathbf{V_{avg,out}}$ ) across $\mathbf{R_L}$ .

Add Filter: Connect the electrolytic capacitor ( $\mathbf{C}$ ) in parallel with the load resistor ( $\mathbf{R_L}$ ). Ensure the correct polarity (negative side to ground/negative line of the rectifier output).
Observation: Observe the output waveform across $\mathbf{R_L}$ on the oscilloscope. The pulsating DC will now be smoothed out, resembling a higher DC level with a small ripple voltage.
Measurement: Measure and record the new DC Average voltage ( $\mathbf{V_{avg,out,filtered}}$ ) and the Peak-to-Peak Ripple Voltage ( $\mathbf{V_{r,p-p}}$ ) from the oscilloscope.

Bridge Rectifier

Circuit Diagram: Connect the four diodes ( $\mathbf{D_1, D_2, D_3, D_4}$ ) in a bridge configuration.
Steps:

Connect the AC source to the two opposite nodes in the bridge structure (the junction of D1 cathode/ $\mathbf{D_4}$ anode and the junction of $\mathbf{D_2}$ cathode/ $\mathbf{D_3}$ anode).
The positive output (pulsating DC) is at the junction of the two diode cathodes ( $\mathbf{D_1}$ and $\mathbf{D_3}$ ).
The negative output (ground reference) is at the junction of the two diode anodes ( $\mathbf{D_2}$ and $\mathbf{D_4}$ ).
Connect the load resistor ( $\mathbf{R_L}$ ) between the positive and negative output terminals.

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