Zener diode-To plot the forward and reverse characteristics of zener diode b. To study the voltage regulation action of a zener diode. Skip to main content

Zener diode-To plot the forward and reverse characteristics of zener diode b. To study the voltage regulation action of a zener diode.

AIM:  a.   To plot the forward and reverse characteristics of zener diode
            b.   To study the voltage regulation action of a zener diode.

zener diode
zener diode
These diodes are special purpose diodes. They are heavily doped p-n diode due to which the width of the depletion region is very small. The breakdown voltage of these diodes is very precise and can be fixed to the desired value. Beyond the breakdown; the voltage across the diode remains constant. Hence these diodes are specially used as voltage regulators in d.c. power supplies. As it acts as a constant voltage source, it is often used as a voltage reference diode.

APPARATUS
                          a o to 15 V dc power supply, zener diode, voltmeters,  milliammeter
FORMULAE
               The dynamic resistance of the diode is given by           rz= ∆Vz /∆Iz

THEORY

ZENER DIODE :

These diodes are special purpose diodes. They are heavily doped p-n diode due to which the width of the depletion region is very small. The breakdown voltage of these diodes is very precise and can be fixed to the desired value. Beyond the breakdown; the voltage across the diode remains constant. Hence these diodes are specially used as voltage regulators in d.c. power supplies. As it acts as a constant voltage source, it is often used as a voltage reference diode.

The breakdown voltage depends on the width of the depletion region which in turn depends upon the doping level of the p-and n-regions. The large current at the breakdown is caused by two mechanisms, namely, zener effect and avalanche effect. Zener effect is predominant for breakdown voltages less than about 8V. The avalanche breakdown is predominant for the voltage greater than 8V. around 8 volts both the effects are predominant.
Zener breakdown does not result in the damage of the junction. Usually, a series resistor Rs, called a limiting resistor, is connected in series with the diode to avoid passing of very large current through the diode. As the zener diode is most often used in the reverse bias condition, the dynamic resistance of the diode in the breakdown region is an important parameter which is to be calculated by using the formula
 Rz = ∆Vz/ ∆ Iz.

PROCEDURE

1. TO PLOT FORWARD CHARACTERISTICS OF ZENER DIODE:

   1. Make the connections as shown in fig for respective diodes (Z1&Z2).
   2. Vary the voltage in steps of 0.25V/0.2V carefully till mA shows deflection.    
   3. Find voltage required for current of 1mA.
   4. Now vary the current in steps of 1mA till 10mA and note down the corresponding value of voltage.

   2. TO PLOT THE REVERSE CHARACTERISTICS:

   1.  Make the connections as shown in the fig.
   2. Vary the i/p voltage in steps of 0.5 V and note down the o/p  voltage(VZ) and  corresponding
       current in mA.
   3.  Observe breakdown voltage carefully at which suddenly current starts flowing.
        Now vary current by 1 mA till 10mA and note down i/p and o/p voltages.

RESULT

1. The forward and reverse characteristics of Zener diode has been studied and shown in Graph.
2. From the characteristics graph and voltage regulation curve, the breakdown voltage is found to be ------------------------------------
3. The voltage regulation using zener diode occurs beyond -------------
                                                       
Answer the followings:

1)      What is the aim of the experiment?
2)      What happens when the reverse bias of the diode is increased?
3)      What is meant by breakdown?
4)      How does the process of breakdown occur in diodes?
5)      What is meant by Zener breakdown?
6)      Under what conditions does zener breakdown occur?
7)      What are the applications of zener diodes?
8)      Which zener is used in the experiment? What is its breakdown voltage?
9)      What happens to the current through the diode if the reverse bias voltage is increased?
      What happens to the voltage?
10)  How does a zener diode behave under forward bias condition?
11)  How much forward voltage is needed to cause current through the diode?
12)  If a zener is rated at 6V, 1/2W, what is the maximum current that can be allowed through it?
13)  What is the need of voltage regulation?
14)  What happens when the input voltage to the regulation section increases?

15)  Interpret the voltage regulation curve with one of its practical application?
Labels:

Comments

Post a Comment

Popular posts from this blog

diwali meaning

दिवाली          दिवाली सिर्फ हिंदू त्यौहार नहीं है बल्कि यह प्रकाश का त्यौहार है। इस त्योहार की रोशनी जो पूरे परिवार के सदस्य को एक साथ लाती है, परिवार के प्रत्येक सदस्य के दिल में शामिल हो जाती है। न सिर्फ परिवार जो आपके और दुनिया भर में रहता है। दिवाली का संदेश खुश रहना और प्यार, देखभाल और दयालुता के साथ साथ रहना और खुशी से जीवन का आनंद लेना है      इस नाम में, दिवाली का दीपक दीपक का अस्तित्व है। लाखों दियो के प्रकाश की उज्ज्वल रोशनी नीली रोशनी के साथ आकाश को सजाया गया है। अंधेरा दियो की प्रकाश की पीले रोशनी से दूर हो रहा है । दीवाली महाकाली , महालक्ष्मी और महासरस्वती के त्योहार के रूप में मनाई जाती है। यही कारण है कि महिलाओं को घर की लक्ष्मी कहा जाता है। भाय्यादुज के दिन, बहन अपने भाई के जीवन वृध्दि की कामना करती थी। दिवाली क्या है? दिवाली रोशनी का पांच दिवसीय त्योहार है, जो दुनिया भर में लाखों हिंदुओं, सिखों और जैनों द्वारा मनाया जाता है। त्यौहार, जो हिंदू नव वर्ष के साथ मेल खाता है, नई शुरुआत और बुराई पर अच्छाई की जीत, और अंधेरे पर प्रकाश मनाता है। दिवाली कब है?
1 comment
Read more

Thomson method-To determine the value of e/m of electron using the bar magnet method.

AIM:  To determine the value of e/m of electron using the bar magnet method. To determine the value of e/m of  electron  using the bar magnet method.   J.J. Thomson, the discoverer of the electron, first determined in 1897 the ratio of the charge  e  of the electron to its mass  m  by applying electric and magnetic fields to a narrow beam of cathode rays. A Cathode Ray Tube (CRT) is a convenient device for determining e/m ratio of the electron. A narrow electron beam is produced in it and the beam can be manipulated by impressed electrical and magnetic fields over a small length of the electron path. The electric field produced by a short length of deflection plates and the magnetic field is applied from outside over the same length. APPARATUS:  A cathode ray tube (CRT), a power supply, two bar magnets, deflection magnetometer, and wooden frame with scales fixed on its arms. FORMULA                                     VD e/m =   ----------------     x 10 11 C/Kg
10 comments
Read more

Best Solar Panels in India for 2019 – Buy Solar Panels for Home & Business Online

Best Solar Panels in India                                                                         Summary: Solar panels also are known as Photovoltaic solar panels, solar modules, solar plates or सौरऊर्जा are made of silicon cells which convert sunlight into electricity. Thus generating clean energy free of cost for a period of 25 years. The best solar panels in India available in the market are classified into two types: polycrystalline and monocrystalline solar panel. Solar panel cost ranges from ₹25 to ₹35 per watt depending on the size of the solar power system. Here's the list of best solar panels you can buy in India right now. These solar panels offer the latest technology combined with premium design and cutting edge features. 1. Luminous Mono Crystalline Solar Panel 335 Watt - 24 Volt Luminous mono crystalline solar panel 335 Watt - 24 Volt is used to generate electricity from sun. It is the maximum wattage solar panels in Luminous. If you ar
4 comments
Read more