Experiment 2 - Zener Diode AND Power Supply PDF

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EXPERIMENT 2 : ZENER DIODE AND POWER SUPPLYLECTURER :SIR MASNAWI MUSTAFFASTUDENT’S NAME :NURINA IZZATI BINTI MD RAPI(2020853716)DATE OF EXPERIMENT :18 thNOVEMBER 2021DATE OF SUBMISSION :4 thDECEMBER 2021EXPERIMENT 2 : ZENER DIODE AND POWER SUPPLYObjectives : Constructing a 5-V power supply.Apparatus...

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EXPERIMENT 2 : ZENER DIODE AND POWER SUPPLY

LECTURER : SIR MASNAWI MUSTAFFA

STUDENT’S NAME : NURINA IZZATI BINTI MD RAPI (2020853716)

DATE OF EXPERIMENT : 18th NOVEMBER 2021

DATE OF SUBMISSION : 4th DECEMBER 2021

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EXPERIMENT 2 : ZENER DIODE AND POWER SUPPLY

Objectives : Constructing a 5-V power supply. Apparatus : Livewire application 1. 6-V AC power supply 2. Bridge Rectifier (BR3) 3. Capacitors (1000 µ𝐹) 4. Multimeter 5. Oscilloscope

Theory : The Zener diode is like a general-purpose signal diode consisting of a silicon PN junction. When biased in the forward direction it behaves just like a normal signal diode passing the rated current, but as soon as a reverse voltage applied across the Zener Diode exceeds the rated voltage of the device, the diode breakdown voltage is reached at which point a process called Avalanche Breakdown occurs in the semiconductors depletion layer and a current starts to flow through the diode to limit this increase in voltage. Zener diodes can be used to produce a stabilised voltage output with low ripple under varying load current condition. By passing a small current through the diode from a voltage source, via a suitable current limiting resistor ( 𝑅 ), the zener diode will conduct sufficient current to maintain a voltage drop of 𝑉 𝑠

.

𝑜𝑢𝑡

A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Electronic circuits need energy to work. In most cases the energy is provided by a circuit called the power supply. A power supply failure will affect all the other circuits. The supply is the key part of an electronic system. Power supplies used rectifier diodes to convert alternating current to direct current. They also use special IC for voltage regulation. The 7805 series of IC regulators operate at a fixed output voltage. The 7805 provides 5-V, the 7812 provides 12-V and 7815 provides 15-V.

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Procedures : Livewire was opened on my laptop. a) Power supply 1. New blank project or file was created. 2. The bridge rectifier connected to the AC power supply. 𝑉

𝑅𝑀𝑆

and frequency was setted to 6-V and

1Hz respectively. 3. An oscilloscope Channel 1 was connected across the + and - terminal of the bridge rectifier and the waveform displayed was observed on the OSK screen as shown in figure below. Maximum and minimum voltage was setted to 9V and -9V respectively, Time to 200ms. The waveform was captured or sketched.

Figure 1: Circuit without Smoothing Capacitor and Voltage Regulator

4. Capacitor was connected to the + and - terminal of the bridge rectifier and the waveform displayed was observed on the OSK screen or graph as shown in figure below. Different values of capacitor were tried. The waveform was sketch and record.

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Figure 2: Circuit with Smoothing Capacitor or Filter

5. The connection of the whole circuit was completed as in the diagram and the waveform was observed across C6.

Figure 3: Circuit with Simple 5V DC Regulated Power-Supply

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Data and Results : From figure 1;

From figure 2; a) Using Capacitor 1000µ𝐹

b) Using Capacitor 2000µ𝐹

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c) Using Capacitor 5000µ𝐹

Figure 3;

Discussion : 1. The graph from Channel 1 (in red) in figure 1, 2 and 3 shows that the waveform displayed on the OSK screen remains the same as shown in the discussion part. This is because input in all figures is the same so that the waveform does not change. 2. The graph From Channel 2 (in blue) in figure 1, 2 and 3 shows that the waveform displayed on the OSK screen is different from each other waveform. This is because output in all figures are different. For example, in figure 1 the circuit without smoothing capacitor and voltage regulator, in figure 2 the circuit contains only smoothing capacitor while in figure 3 it contains smoothing capacitor and voltage regulator. 3. Graph of XSC1 shows sine wave for the input when sine wave passes through a bridge rectifier the graph shows half wave, bridge rectifier allows electric current during both positive and negative half cycles of the input.

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4. Graphs of XSC2 use three different values of capacitor which is 1000µ𝐹, 2000µ𝐹 and 5000, all the graph shows different ripple. The higher values of the capacitor, the output waveform show less ripple. Capacitors are energy storage devices. This shows the effect of capacitors. 5. Graph of XSC3 output shows a straight line because the voltage regulator was connected to regular or stabilize the output voltage.

Conclusion : A 5-V power supply was constructed using a bridge rectifier, a filter and a regulator. A bridge rectifier consists of diodes to convert voltage from AC to DC but the voltage was not pure direct current because it still contains an AC component called ripple. A capacitor or filter was used to clean the voltage from the ripple. The higher capacitor values, less ripple waveform shows. A voltage regulator was used to regularize and provide the constant DC voltage. Thus, a 5-V power supply was built.

References : 1. Laboratory Manual PHY547 (Vol. 1). (2020). Masnawi Mustaffa [Print]. 2. Admin. (2021, January 23). Bridge rectifier – construction, working, advantages. BYJUS., from https://byjus.com/physics/bridge-rectifier/. 3. Yaman Electronics. 2021. Design 5V DC Power Supply (Easy Step By Step Guide). [online] Available

at:

https://www.yamanelectronics.com/design-5v-500ma-dc-power-supply/#Conclusion.

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