Analog Electronics Lab Manual Experiment No 1-5
Experiment No. 1
Object:
Familiarizations of Electronic Components and Usage of Multi-meter, Oscilloscope and Signal Generator
Objective:
1. Identification of Various Components (i.e Resister, Capacitor, Diodes)
2. Familiarization with Breadboard, Multimeter, Power Supply, Oscilloscope & Signal Generator.
Theory:
Breadboard:
Fig.1: A Typical Breadboard
Fig.2: Connection Details
A real breadboard is shown in Fig. 1 and the connection details on its rear side are shown in Fig. 2. The five holes in each individual column on either side of the central groove are electrically connected to each other, but remain insulated from all other sets of holes. In addition to the main columns of holes, however, you'll note four sets or groups of holes along the top and bottom. Each of these consists of five separate sets of five holes each, for a total of 25 holes. These groups of 25 holes are all connected together on either side of the dotted line indicated on Fig.1 and needs an external connection if one wishes the entire row to be connected. This makes them ideal for distributing power to multiple ICs or other circuits.
Function generator:
Function Generators are instruments capable of generating an ac signal of any frequency (~ 100Hz – hundreds of kHz), voltage (~1mv – 20V) and various forms (e.g. sine wave, Square pulse, Saw tooth wave, and Triangular wave or noise waveform). They also provide a continuously variable dc offset, variable duty cycle. They are usually of 2 types: (i) analog and (ii) Digital.
Some of the front panel controls of a typical function generator are:
1. Power Switch : For switching on the power supply
2. Digital Display : This is a 4 digit frequency meter
3. OFFSET : This knob is for adding a dc voltage to the output signal
4. Amplitude : This does the continuous adjustment of output voltage
5. Speed : This is for setting speed
6. Width : This knob is for setting the width
7. Frequency : This knob is for selecting the frequency range from 0.3 Hz to 3MHz in Decade steps.
8. Sweep On : This is a push button for activating internal sweep
9. Mode Selection : Push Button for triangular, sine Square etc.
10. BNC connector : This is a 50 Ω output BNC connector
11. -20 db, - 20 db : A push button control for -20 db attenuation. When both buttons are
pushed then a total of 40 db attenuation is got.
Cathode ray oscilloscope (CRO):
CRO CONTROLS FROM THE FRONT PANEL
1. Intensity:
This knob controls the brightness of the trace by adjusting the number of electrons emerging from the gun
2. Focus:
This control is for making the trace on the screen sharper. It is connected to the anode of the electron gun whose voltage collimates the electron beam.
3. Vertical Position & Horizontal Position:
Through these controls the beam can be positioned at variable vertical or horizontal positions as desired. These knobs apply a dc voltage to the vertical and horizontal deflection plates.
4. V / Div:
This control is used to control the voltage sensitivity. This is internally connected to an attenuator of the vertical system. It determines the voltage required by the vertical plates to deflect the beam vertically by one division.
5. Time / Div:
This determines the time taken for the spot to move horizontally across one division of the screen when the sweep is generated by triggering process. The signal which is fed to the vertical deflection plates provides the triggering to the waveform. Each position of the time/ div knob is applicable for a particular frequency. This determines the horizontal sensitivity of the observed signal.
6. Trigger Source:
This selects the source of the trigger to be applied to the saw tooth waveform. There are usually three possible sources (i) Internal: This is mostly used for all applications. The vertical signal applies the triggering signal. (ii) Line:This is generally used when the voltage to be measured is related to the line voltage. This selects the 50Hz line voltage. (iii) Ext. In this case an external signal is applied to trigger the saw tooth waveform.
7. Slope:
This determines whether the time base circuit responds to the positive or negative slope of the triggering waveform.
8. Level:
This determines the amplitude level on the triggering waveform which can start the sweep
9. AC, DC, and GND:
This selects the coupling mechanism for the input signal to the CRO. In dc mode the vertical amplifier receives both ac and dc components of the input signal. In ac mode the coupling capacitor blocks all dc components and displays only pure ac waveform. In Gnd configuration, the input signal is grounded and one gets a straight line. To measure the dc component of any signal (ac or dc), one has to switch from ac to dc mode and observe the vertical shift of the waveform. The amount of vertical shift in volts gives the corresponding dc component.
10. X-Y mode:
In this mode of operation two signals are superimposed at right angles on each other. The saw tooth time base circuit is disconnected from the horizontal deflection plates and the external signal which s fed to channel two is given to time base instead. Hence if two sine waves are fed to two channels respectively then the electron beam will undergo deflection according to right angle superposition of two sine waves. It will trace lissajous figures.
DC Power source:
DC power sources provide a relatively constant (DC) power. Most DC power sources fall into one of two categories: batteries or DC power supplies. Batteries perform an electrochemical reaction in order to generate electrical power. DC power supplies convert the 50 Hz AC power readily available in most homes and laboratories into a DC power with some desired current and/or voltage. Our discussion will focus on DC power supplies. Figure shows a typical DC power supply.
Digital Multi-meter
Digital multi-meters (DMM) are multipurpose devices used to measure various circuit parameters. DMMs are commonly capable of measuring the following quantities: DC (constant) voltages, AC (sinusoidal varying) voltages, DC current, AC current, resistance and capacitance. Many DMMs are capable of measuring additional quantities, such as frequency, conductance, and inductance. In this lab assignment, we will use DMMs to measure DC current and voltage and resistance.
Exercises to perform:
1. Construct a simple series parallel of circuit on breadboard and get the result.
2. Adjust 10 kHz frequency on CRO.
3. Adjust 10 Vp-p voltages on CRO.
4. Generate sine wave with 50Hz frequency on CRO.
5. Generate square wave with 50Hz frequency on CRO.
6. Generate triangular wave with 40 Hz frequency on CRO.
7. Measure resistance of resistor by multi-meter.
8. Adjust 60v DC supply by DC source.
Viva questions:
1. What is CRO and what its use.
2. What is multi-meter why it is called so?
3. Is capacitance is measured by multi-meter.
4. What are the quantities measured by multi-meter.
5. What is DC regulated Power supply and what its use.
6. What is signal generator and what is its need.
7. What are the type of signals can be generate be signal generator.
8. What is time period?
9. What is cycle?
10. What is frequency?
11. What is peak-peak voltage?
Etc….
Conclusion:
…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..
Space for Notes:
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………
Experiment No. 2
Object
Colour Code and Testing of Components.
Objectives:
1. Colour Code of Resister and Capacitor,
2. Testing of Electronic Components (i.e diode, transistor & meters).
Theory
BASIC COMPONENTS:
Basic components like capacitors, resistors, inductors, diodes, light emitting diode (led) and transistors can be divided into 2 categories: (i) Passive components like resistors and capacitors and (ii) Active components like diodes and transistors. The difference between the above two categories is that active components can generate energy whereas passive components can not generate energy. In other words active components can increase power of a signal whereas passive components often cause the power to be lost.
Resistor color code:
Resistors are manufactured in what are called “preferred values” with their resistance value printed onto their body in coloured ink.
The resistance value, tolerance, and wattage rating are generally printed onto the body of the resistor as numbers or letters when the resistors body is big enough to read the print, such as large power resistors. But when the resistor is small such as a 1/4W carbon or film type, these specifications must be shown in some other manner as the print would be too small to read.
So to overcome this, small resistors use coloured painted bands to indicate both their resistive value and their tolerance with the physical size of the resistor indicating its wattage rating. These coloured painted bands produce a system of identification generally known as a Resistors Colour Code.
The resistor colour code markings are always read one band at a time starting from the left to the right, with the larger width tolerance band oriented to the right side indicating its tolerance. By matching the colour of the first band with its associated number in the digit column of the colour chart below the first digit is identified and this represents the first digit of the resistance value.
Again, by matching the colour of the second band with its associated number in the digit column of the colour chart we get the second digit of the resistance value and so on. Then the resistor colour code is read from left to right as illustrated below chart.
Calculating Resistor Values:
The Resistor Colour Code system is all well and good but we need to understand how to apply it in order to get the correct value of the resistor. The “left-hand” or the most significant coloured band is the band which is nearest to a connecting lead with the colour coded bands being read from left-to-right as follows;
Digit, Digit, Multiplier = Colour, Colour x 10 colour In Ohm’s (Ω’s)
For example, a resistor has the following coloured markings;
Yellow Violet Red = 4 7 2 = 4 7 x 102 = 4700Ω or 4k7.
The fourth and fifth bands are used to determine the percentage tolerance of the resistor. Resistor tolerance is a measure of the resistors variation from the specified resistive value and is a consequence of the manufacturing process and is expressed as a percentage of its “nominal” or preferred value.
Typical resistor tolerances for film resistors range from 1% to 10% while carbon resistors have tolerances up to 20%. Resistors with tolerances lower than 2% are called precision resistors with the or lower tolerance resistors being more expensive.
Most five band resistors are precision resistors with tolerances of either 1% or 2% while most of the four band resistors have tolerances of 5%, 10% and 20%. The colour code used to denote the tolerance rating of a resistor is given as;
Brown = 1%, Red = 2%, Gold = 5%, Silver = 10 %
If resistor has no fourth tolerance band then the default tolerance would be at 20%.
The Standard Resistor Colour Code Chart
|
The Resistor Colour Code Table
|
Capacitor Colour Codes:
Generally, the actual values of Capacitance, Voltage or Tolerance are marked onto the body of the capacitors in the form of alphanumeric characters. However, when the value of the capacitance is of a decimal value problems arise with the marking of the “Decimal Point” as it could easily not be noticed resulting in a misreading of the actual capacitance value. Instead letters such asp (pico) or n (nano) are used in place of the decimal point to identify its position and the weight of the number.
For example, a capacitor can be labelled as, n47 = 0.47nF, 4n7 = 4.7nF or 47n = 47nF and so on. Also, sometimes capacitors are marked with the capital letter K to signify a value of one thousand pico-Farads, so for example, a capacitor with the markings of 100Kwould be 100 x 1000pF or 100nF.
To reduce the confusion regarding letters, numbers and decimal points, an International colour coding scheme was developed many years ago as a simple way of identifying capacitor values and tolerances. It consists of coloured bands (in spectral order) known commonly as the Capacitor Colour Code system and whose meanings are illustrated below:
Capacitor Colour Code Table
Band
Colour |
DigitA
|
Digit B
|
MultiplierD
|
Tolerance(T) > 10pf
|
Tolerance(T) < 10pf
|
Temperature Coefficien(TC)
|
Black
|
0
|
0
|
x1
|
± 20%
|
Comments
Post a Comment