Identification of Resistor Color Codes and Capacitor Markings
AIM:
To determine the value of the given resistors and Capacitors using standard color Codes.
APPARATUS REQUIRED:
S.No | Components Required | Specification | Quantity |
1 | Resistors | 4 Band | 3 |
2 | Resistors | 5 Band | 3 |
3 | Capacitors | Ceramic | 3 |
4 | Capacitors | Electrolytic | 3 |
THEORY:
Resistors
Resistors are electrical devices that act to reduce current flow and at the same time act to lower voltage levels within circuits. The relationship between the voltage applied across a resistor and the current through it is given by V = IR.
There are numerous applications for resistors. Resistors are used to set operating current and signal levels, provide voltage reduction, set precise gain values in precision circuits, act as shunts in ammeters and voltage meters, behave as damping agents in oscillators, act as bus and line terminators in digital circuits, and provide feedback networks for amplifiers.
Resistors may have fixed resistances, or they may be designed to have variable resistances. They also may have resistances that change with light or heat exposure.
Capacitors
Capacitors act as temporary charge-storage units, whose behavior can be described by I = CdV/dt. This equation states that a capacitor “likes” to pass current when the voltage across its leads is changing with time (e.g., high-frequency ac signals) but “hates” to pass current when the applied voltage is constant (e.g., dc signals). A capacitor’s “dislike” for passing a current is given by its capacitive reactance Xc = 1/ωC (or Zc =−j/ωC in complex form). As the applied voltage’s frequency approaches infinity, the capacitor’s reactance goes to zero, and it acts like a perfect conductor. However, as the frequency approaches zero, the capacitor’s reactance goes to infinity, and it acts like an infinitely large resistor. Changing the value of C also affects the reactance. As C gets large, the reactance decreases, and the displacement current increases.
PROCEDURE:
Resistor
1. Keep the given resistor in an appropriate position.
2. Identify the colors in the given resistor.
3. Apply standard color code technique to determine the unknown resistor
value.
Capacitor
1. Identify the value written over the given Capacitor.
2. Convert the identified value into Capacitor Value using a Standard rule.
RESULT:
Thus the given resistor and capacitor values are identified using the Standard Color Code Technique.
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Characteristics of PN Junction Diode
AIM:
To determine the forward and reverse characteristics of a PN Junction Diode.
APPARATUS REQUIRED:
S.No | Components | Specification | quantity |
1 | Diode | 1N 4007 | 1 |
2 | Resistor | 1kohm | 1 |
3 | Ammeter | (0-30)mA | 1 |
4 | Voltmeter | (0-30)V | 1 |
5 | Bread Board | 1 | |
5 | Regulated Power Supply | 0-30v | 1 |
THEORY:
PN Junction Diode
A pn-junction diode (rectifier diode) is formed by sandwiching together n-type and p-type silicon. In practice, manufacturers grow an n-type silicon crystal and then abruptly change it to a p-type crystal. Then either a glass or plastic coating is placed around the joined crystals. The n side is the cathode end, and the p side is the anode end. The trick to making a one-way gate from these combined pieces of silicon is getting the charge carriers in both the n-type and p-type silicon to interact in such a way that when a voltage is applied across the device, current will flow in only one direction. Both n-type and p-type silicon conducts electric current; one does it with electrons (n-type), and the other does it with holes (p-type). Now the important feature to note here, which makes a diode work (act as a one-way gate), is the manner in which the two types of charge carriers interact with each other and how they interact with an applied electrical field supplied by an external voltage across its leads.
When a diode is connected to a battery, electrons from the n side and holes from the p side are forced toward the center (pn interface) by the electrical field supplied by the battery. The electrons and holes combine, and current passes through the diode.When a diode is arranged in this way, it is said to be forward-biased.
Reverse-Biased
When a diode is connected to a battery, holes in the n side are forced to the left, while electrons in the p side are forced to the right. This results in an empty zone around the pn junction that is free of charge carriers, better known as the depletion region. This depletion region has an insulative quality that prevents current from flowing through the diode. When a diode is arranged in this way, it is said to be reverse-biased.
PROCEDURE:
1. Connect the circuit as per given in the Circuit Diagram.
2. Vary the input voltage and note down the current through and voltage across the diode.
3. Plot the Graph.
RESULT
Thus the Characteristics of PN Junction Diode were determined and the graph was plotted.
Characteristics of Zener Diode
AIM:
To determine the forward and reverse characteristics of a Zener Diode.
APPARATUS REQUIRED:
S.No | Components | Specification | quantity |
1 | Diode | Z9.1v | 1 |
2 | Resistor | 1kohm | 1 |
3 | Ammeter | (0-30)mA | 1 |
4 | Voltmeter | (0-30)V | 1 |
5 | Bread Board | 1 | |
5 | Regulated Power Supply | 0-30v | 1 |
THEORY:
A zener diode is a device that acts as a typical pn-junction diode when it comes to forward biasing, but it also has the ability to conduct in the reverse-biased direction when a specific breakdown voltage (VB) is reached. Zener diodes typically have breakdown voltages in the range of a few volts to a few hundred volts (although larger effective breakdown voltages can be reached by placing zener diodes in series).
PROCEDURE:
1. Connect the circuit as per given in the Circuit Diagram.
2. Vary the input voltage and note down the current through and voltage across the diode.
3. Plot the Graph.
RESULT:
Thus the Characteristics of Zener Diode were determined and the graph was plotted.
Characteristics of BJT- CE Configuration
AIM:
To study the input output characteristics of Bipolar Junction Transistor in Common Emitter Configuration.
APPARATUS REQUIRED:
S.No | Components | Specification | quantity |
1 | Transistor | BC-107 | 1 |
2 | Resistor | 1kohm | 1 |
3 | Ammeter | (0-30)mA | 1 |
4 | Voltmeter | (0-30)V | 1 |
5 | Bread Board | 1 | |
5 | Regulated Power Supply | 0-30v | 1 |
THEORY:
Bipolar transistors are three-terminal devices that act as electrically controlled switches or as amplifier controls. These devices come in either npn or pnp configurations. An npn bipolar transistor uses a small input current and positive voltage at its base (relative to its emitter) to control a much larger collector-to-emitter current. Conversely, a pnp transistor uses a small output base current and negative base voltage (relative its emitter) to control a larger emitter-to-collector current.
Bipolar transistors are incredibly useful devices. Their ability to control current flow by means of applied control signals makes them essential elements in electrically controlled switching circuits, current-regulator circuits, voltage-regulator circuits, amplifier circuits, oscillator circuits, and memory circuits.
PROCEDURE:
INPUT CHARACTERISTICS
1. Connect the circuit as the circuit diagram.
2. Set VCE=5V and vary VBE in steps.
3. Note down the corresponding values of IB.
4. Repeat the same procedure for various values of VCE.
5. Plot the graph VBE against IB for a constant VCE.
OUTPUT CHARACTERISTICS
1.Connect the circuit as the circuit diagram.
2.Set IB=20uA and vary VCE in steps of 1V.
3.Note down the corresponding values of IC.
4.Repeat the same procedure for different values of IB.
5.Plot the graph VCE against IC for constant IB.
RESULT:
Thus the input and output characteristics of a Bipolar Transistor in Common Emitter Configuration is thus studied.
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