Experiment-15 :- Study Of LCR Meter

LCR- The inductance (L), capacitance (C), and resistance (R) of an electrical component are measured using an LCR meter, a type of electronic test equipment. The phase difference between the current and voltage waveforms is also measured by LCR meter in addition to the ratio of the current and voltage RMS values. 

Basic measuring principles for LCR meter:

Impedance is a physical property that is measured using LCR meter, which are measuring equipment. The quantifier Z is used to express impedance, which is resistance to the passage of an AC current. It can be determined using the voltage V between the measurement target’s terminals and the current I flowing to it. Impedance is a vector that is expressed on a complex plane.

LCR meter’s front panel:

Control terminals on the LCR meter’s front panel.

1. ON/OFF Switch:

LCR meters power can be turned on or off using the ON/OFF switch. The main supply is connected with a LCR meter while the switch is in the ON position. When the LCR meters is turned ON, the indicator on the front panel will begin to illuminate.

2. Testing Terminals: The front panel’s two points are test terminals. To these test terminals is attached the component that will be measured.

3. Function Selector: The function selector is used to put the meter in the proper mode to measure a certain kind of component. The function selector should be set to R mode for resistance measurements, L mode for inductance measurements, and C mode for capacitance measurements if they are to be done simultaneously.

4. Range Selector: With the help of the range selector, components with high magnitude or low magnitude values can be measured with ease.

5. Scale: The final values of the measurement will be displayed on the LCR meter’s calibrated scale.

Construction of LCR Meter:

• Wheatstone bridge and
• RC ratio arm circuits

are important parts of the LCR meter. The component whose value needs to be determined is attached to one of the bridge’s arms.

For the various types of measures, there are different provisions.

DC Excitation: By stimulating the bridge with DC voltage, DC quantities will be measured.

AC Excitation: The Wheatstone bridge must be excited with an AC signal in order to conduct AC measurements. The oscillator is employed in the circuit to provide AC excitation. It produces a frequency of one kilohertz.

Working of LCR Meter:

To achieve full balance, the bridge is set at the null position. In addition to balancing the bridge, the meter’s sensitivity needs to be modified. In an emitter follower circuit, the bridge’s output is fed. An input to the detector amplifier is provided as the emitter follower circuit’s output.

             

                                                                               BRIDGE CONNECTION 

An input to the detector amplifier is provided as the emitter follower circuit’s output. A strong measuring signal of great magnitude is required in order to achieve the sustainable indication.

The attenuation factor causes the magnitude of the measured signal to decrease due to use of amplifier.

In order to obtain a DC output signal during AC excitation in a bridge, a rectifier is used.

Types of LCR Meter:

LCR Meter are 2 types,

• Handheld LCR Meter and
• Benchtop LCR Meter

Handheld LCR Meter:

The portability and small weight of handheld LCR meter are benefits. In this meter typically have an accuracy of +/-1%.

Benchtop LCR Meter:

Benchtop LCR meter typically come with more capabilities than handheld versions, including programmable frequencies, greater measurement accuracy down to 0.01%, computer control, and data collection for automated applications.

                                                        BENCHTOP LCR METER

Advantages of LCR Meter:

• LCR meter offer quick output and accurate readings.
• For accurate measurements LCR meter are used with test voltage and frequency.

Disadvantages of LCR Meter:

If the test voltage applied to the bridge of the LCR meter is high while excitation, the circuit will burn out. 

Application of LCR Meter:

• The resistance, capacitance, and inductance of circuits and parts are measured at various frequencies using an LCR meter.
• These instruments are utilized to test an impedance, a physical characteristic denoted by the quantifier “Z.”
• Electrical engineers and various manufacturing industries frequently utilize this measurement instrument.

Experiment - 14 :-Identification of different types of inductors and its specifications.

 Theory:

An inductor (also choke, coil or reactor) is a passive two-terminal electrical component that stores energy in its magnetic field. For comparison, capacitor stores energy in an electric field and a resistor does not store energy but rather dissipates energy as heat. An inductor is usually made from a coil of conducting material, like copper wire, that is then wrapped around a core made from either air or a magnetic metal.

While a capacitor does not like changes in voltage, an inductor does not like changes in current.

Inductor is a device which can store energy in the form of magnetic field. Inductor opposes a sudden change in the flow of current. The function of an inductor is to provide opposition to a changing or varying current

Whenever a current change occurs within the coil windings, a voltage is induced across the ends of the coil. The polarity of the induced voltage is such that it opposes the current change occurring withinn the inductor. In more general terms, inductors are the opposite of capacitor, in that they are able to pass a dc current and block an ac current. The basic unit of inductance is the Henry (H). 

Mutual inductance: Inductor store energy in form of magnetic field. This field of an inductor extends outside of inductor & can be affected another inductor close by.

Which utilizes mutual inductance to alter voltage or current output is called transformer. Inductor that supplies current called as primary coil & inductor that picks up magnetic field is called secondary winding.

Types: 1. Fixed inductors: 

• Air core inductor: It consist no. of turns of wire on ordinary cardboard former. Since there is air inside former. These are used in RF frequencies in turning coils. 

• Iron core inductor: The coil wounded over solid or laminated iron core. 

This iron core is laminated pressed together but insulated from each other.

2. Variable inductors: 

They are used in tuning circuit for radio frequency. The winding is placed over a fiber or ceramic former & to change inductance, a ferrite core is employed. By changing position of screwed ferrite core inductance can be changed.

Conclusion: 

Experiment -13: - To Identify Different Types of Resistors From physical Appearance.

 

Aim: - To Identify Different Types of Resistors From physical Appearance.

Materials Required: - Various types of resistors, Measuring instruments Voltmeter, Ammeter, Ohm meter etc.

Theory:-

Resistance is the property of a material which opposes the flow of electric charges through it. The unit for measuring resistance is Ohms. It is measured using the Ohmmeter.

Resistors are components used in electrical and electronic circuits for making different voltages required for different electronic components.

There are two types of Resistors:-

The Ohm value (resistance) of these resistors is constant and cannot be altered. The examples are carbon resistors, Ceramic resistors and Wire wound resistors.

Different types of Variable resistors

These resistors, the ohm value can be varying. The examples are potentiometer, Preset, Fan regulator etc.

Experiment - 12:- Measure DC And AC Power Using Power Meter

 Current and Voltage Measurements with Multimeter 

 INTRODUCTION

1.1. Multimeter A multimeter is a measuring instrument that we will use frequently throughout electrical experiments. So it is better to learn how to use a multimeter. 

A Multimeter is an electronic instrument, every electronic technician and engineers widely used piece of test equipment. A multimeter is mainly used to measure the three basic electrical characteristics of voltage, current, and resistance. It can also be used to test continuity between two points in an electrical circuit. This post mainly introduces the basic information of multimeters, applications, and types of multimeters are in. Let’s see all of these. The multimeter has multi functionalities like, it acts like ammeter, voltmeter, and ohmmeter. It is a handheld device with positive and negative indicator needle over a numeric LCD digital display. Multimeters can be used for testing batteries, household wiring, electric motors, and power supplies.

1.1.1. Applications: The applications of ammeter mainly involve in various electrical and electronic projects for components testing and also used in different measurement applications in the multimeter. 

1 Temperature and Environmental Applications

• Low-cost weather station 
• DMM internal temperature 

2 Voltage Measurements 

• High and low-value DC measurement
• Peak to Peak and DC average measurement

3 Current Measurements

• DC measurement
• True RMS AC 

4 Resistance Measurement 

• Micro ohmmeter 
• Measuring resistance with constant voltage 
• Measuring resistance with constant current 

5 Time and Frequency measurement 

• Fast frequency 
• Time measurement

 1.1.2. Types of Multimeters: 

There are different types of multimeters like Analog, Digital, and Fluke multimeters.

Digital Multimeter: We mostly used multimeter is a digital multimeter (DMM). The DMM performs all functions from AC to DC other than analog. It has two probes positive and negative indicated with black and red color is shown in the figure. The black probe connected to COM JACK and red probe connected by user requirement to measure ohm, volt, or amperes. The jack marked VΩ and the COM jack on the right of the picture are used for measuring voltages, resistance, and for testing a diode. The two jacks are utilized when an LCD that shows what is being measured (volts, ohms, amps, etc.). Overload protection prevents damage to the meter and the circuit and protects the user. 

The Digital Multimeter consists of an LCD, a knob to select various ranges of the three electrical characteristics, an internal circuitry consisting of a signal conditioning circuitry, an analog to digital converter. The PCB consists of concentric rings which are connected or disconnected based on the position of the knob. Thus as the required parameter and the range are selected, the section of the PCB is activated to perform the corresponding measurement. To measure the resistance, current flows from a constant current source through the unknown resistor and the voltage across the resistor are amplified and fed to an Analog to Digital Converter and the resultant output in form of resistance is displayed on the digital display. To measure an unknown AC voltage, the voltage is first attenuated to get the suitable range and then rectified to DC signal and the analog DC signal is fed to A/D converter to get the display, which indicates the RMS value of the AC signal. Similarly Figure 1.Digital multimeter to measure an AC or DC, the unknown input is first converted to a voltage signal and then fed to an analog to digital converter to get the desired output (with rectification in case of AC signal). 

II.APPARATUS

Resistance, cables, multimeter, basic electrical set. 

III. EXPERIMENTAL PROCEDURE 

1) Set up the circuit provided on the upside. 

2) If you have one multimeter, prepare it for 2 situations. You can use your multimeter for measuring current and voltage. 

3) Please make the connection of power supply. 

4) Do not forget that Ammeters are connected in series so that the current flows through them. The ideal ammeter has a resistance of zero. Voltmeters are connected in parallel to resistive elements in the circuit so that they measure the potential difference across (on each side of) the element. 

5) In this experiment, please fill the Table 1 for this circuit. 

Theory-20 :-Scanner Troubleshooting

 Solving scanner problems. Checking an unresponsive scanner 

 If your scanner is not responding, then make sure: 

• The printer is turned on. 
• The printer cable is securely attached to the printer and the host computer, print server, option, or another network device. 
• The power cord is plugged into the printer and a properly grounded electrical outlet. 
• The electrical outlet is not turned off by any switch or breaker. 
• The printer is not plugged into any surge protectors, uninterrupted power supplies, or extension cords. 
•  Other electrical equipment plugged into the outlet is working. 

Once you have checked each of these possibilities, turn the printer off and then back on. This often fixes the problem with the scanner. 

Scan was not successful.  

These are possible solutions. Try one or more of the following: 

Check the cable connections.

Make sure the network or USB cable is securely connected to the computer and the printer. 

An error may have occurred in the program. 

Turn off and then restart the computer.  

Scanning takes too long or freezes the computer. 

Other software programs may be interfering with scanning.

Close all programs not being used. 

These are possible solutions. Try one or more of the following: 

The scan resolution may be set too high.

Select a lower scan resolution.

Poor scanned image quality 

These are possible solutions. Try one or more of the following: 

Check the display for error messages.

Clear any error messages. 

The scanner glass may be dirty.

Clean the scanner glass with a clean, lint‐free cloth dampened with water. For more information, see Cleaning the scanner glass. 

Adjust the scan resolution.

Increase the resolution of the scan for a higher quality output. 

Check the quality of the original document.  

Make sure the quality of the original document is satisfactory. 

Check the document placement. 

Make sure the document or photo is loaded face down on the scanner glass in the upper left corner.  Partial document or photo scans 

These are possible solutions. Try one or more of the following: 

Check the document placement Make sure the document or photo is loaded face down on the scanner glass in the upper left corner. 

Check the paper size setting. 

Make sure the paper size setting matches the paper loaded in the tray:

1. From the printer control panel, check the Paper Size setting from the Paper menu. 
2. Before sending the job to print, specify the correct size setting: 

•  For Windows users, specify the size from Print Properties. 
•  For Macintosh users, specify the size from the Page Setup dialog. Cannot scan from a computer.

These are possible solutions. Try one or more of the following: 

Check the display for error messages. 

Clear any error messages. 

Check the power. 

Make sure the printer is plugged in, the power is on, and Ready appears. 

Check the cable connections. 

Make sure the network or USB cable is securely connected to the computer and the printer. 

Theory-17 :- How Scanner Works

 Digital Scanner- Convert an image/photo from analog to digital format.

APPLICATION OF SCANNERS:

1. Compact document scanners, handheld scanners, photo scanners, flatbed scanners, and drum scanners
2. CCD sensors are also found in video and digital cameras.

Theory-20 :-Multifunction Device /Printer (MFd/P)?

 What is a Multifunction Printer (MFP)?

A multifunction printer (MFP), an all-in-one, or multifunction device, is a piece of office technology that integrates multiple functions such as printing, copying, faxing, and scanning into a single compact machine. Intelligent MFPs can also access the internet and print directly from an intuitive, user-friendly display panel, similar to a computer. In addition, most modern MFPs have several convenient finishing options, including:

• Collating
• Stapling
• Folding
• Duplex printing
• Booklet making
• Automatic hole punching

In most office environments, you need to be able to print, copy, fax, and scan, but it's not necessarily wise or feasible to use separate devices for each. MFPs offer small to medium-sized businesses (SMBs) and large enterprises a strategic way to consolidate printer fleets, conserve office space, reduce energy costs, and improve workflow.

3 Types of Multifunction Printers (MFPs)

For a company to select an MFP model that best fits its printing needs, they need a basic understanding of the options available. There're several types of multifunction printers - black and white (B&W), color, and compact. Each MFP type has similar core functions but offers unique advantages.

1. Monochrome or B&W Multifunction

Monochrome or black and white (B&W) multifunction printers are suitable for businesses that don't need to print in color and want to save money from the minimal upkeep and energy consumption that these devices require. Since monochrome MFPs only use one cartridge—black—they tend to be less expensive than color MFPs.

2. Color Multifunction

Color multifunction printers deliver high-resolution color and image quality. With color-specific capabilities, including Pantone colors and color scanning, color MFPs have the flexibility to print various color-intensive documents like financial charts, graphs, and marketing materials. Businesses should remember that color MFPs typically print slower and are more expensive than B&W MFPs.

3. Compact Multifunction

Compact multifunction printers have all the features of a full-size MFP, but they're smaller—making them easier to fit into any office environment. Some compact MFPs can print in B&W and color, while other models only print in black and white. 

Theory- 18 :- Barcode Scanner

Barcode Scanner 

What is a bar code scanner? 

A barcode reader, also called a price scanner or point-of-sale (POS) scanner, is a hand-held or stationary input device used to capture and read information contained in a barcode.

A barcode reader comprises a scanner, a decoder (either built-in or external), and a cable used to connect the reader with the computer or POS system.

How do barcode readers work?

Because a barcode reader merely captures and translates the barcode into numbers and/or letters, the data must be sent to a computer so a software application can translate the data into information.

Barcode scanners can be connected to a computer through a serial port, keyboard port or interface device called a wedge. A barcode reader works by directing a beam of light across the barcode and measuring the amount and pattern of the light that is reflected.

The scanner converts the light energy into electrical energy, which is then converted into data by the decoder and forwarded to a computer.

What are the advantages of barcode readers?

Barcode readers offer several advantages in retail environments:

• reduced pricing errors
• increased accuracy and efficiency
• improved customer service
• reduced inventory levels

How many types of barcode readers are there?

There are two types of barcode readers: handheld and fixed position.

• Handheld barcode readers are used in a wide variety of settings, including retail stores, warehouses and office buildings.
• Fixed-position barcode readers are generally used in manufacturing and logistics applications to track inventory or products as they move through the production process.

Barcode readers come in many forms depending on their use case:

• Pen wand barcode readers contain no moving parts and are known for their durability and low cost. They are typically used to scan barcodes that are printed on paper labels -- for example, in libraries, package delivery and office settings.
• Slot scanners remain stationary, and the item bearing the bar code is pulled through the slot manually. Slot scanners are typically used to scan bar codes on identification cards -- for example, for time and attendance tracking or physical access control.
• CCD scanners have a better read range than pen wands and are often used in retail sales via a "gun" type interface that is held only one inch from the bar code. Each time the bar code is scanned, several readings are taken to reduce the possibility of errors.
• Image scanners use a small video camera to capture an image of the bar code and then use sophisticated digital image processing techniques to decode the information in the barcode. An image scanner can read a bar code from about 3 to 9 inches away and typically costs less than a laser scanner.
• Laser scanners, either hand-held or stationary, use a system of mirrors and lenses to allow the scanner to read the barcode regardless of orientation and can easily read a bar code up to 24 inches away.
• 3D scanners create a three-dimensional image of the bar code, which allows it to be read from any angle. 3D barcode scanners are typically used in industrial settings, such as automotive assembly or aerospace manufacturing. Barcode readers are a critical part of many businesses, and their barcode scanning needs vary depending on the industry and application.
• CGI scanners are used to read barcodes that are printed on curved surfaces, such as cans or pipes. CGI scanners are typically used in the food and beverage industry.

Are there any disadvantages to using barcode readers?

There are a few disadvantages to barcode readers:

• The possibility of misreads, which can lead to data errors;
• The need for a clear line of sight between the barcode and the scanner; and
• The need for barcodes to be printed on labels or tags.

Theory - 22:- Meaning and Application of resonance. Series and parallel resonance circuits.

Meaning and Application of resonance. Series and parallel resonance circuits. 

The specialty of this LC network is its property, known as resonance. Whenever an inductor and a capacitor are connected in parallel as shown in Fig 1 or in series as shown in Fig 2, the circuits exhibit a special phenomenon known as resonance. Resonance, in simple terms, means, the ability to select a particular frequency from the fed signal consisting of signals of different frequencies (wide band of frequencies) 

Impedance of series resonance circuit 

A simple series LC circuit   shown in Fig 3a. In this series LC circuit 

• Resistance R is the total resistance of the series circuit (interna1 resistance) in ohms,  
• XL is the inductive reactance in ohms, and 
• Xc is the total capacitive reactance in ohms. 

All though the unit of measure of reactance and resistance Is the same(ohms) the impedance, Z of the circuit is not given by the simple addition of R, XL and Xc. This is because, XL is +90° out of phase with R and Xc is ‐900 out of phase. with R. Hence the impedance Z of the circuit is the phasor addition of the resistive and reactive components as shown by dotted lines in Therefore, Impedance Z of the circuit is given by,  

Note that the applied voltage is not equal to the sum of voltage drops across reactive component X and resistive component. This is again because the voltage drops are not in phase. But the phasor sums of VR, and VX, will be equal to the applied voltage as given below, 

In this condition, the impedance Z of the circuit will not only be purely resistive but also minimum.  Since the reactance of Land Care frequency dependent, at some particular frequency say f,, the inductive reactance X, becomes equal to the capacitive reactance XC. In such a case, since the impedance of the circuit will be purely resistive and minimum, current through the circuit will be maximum and will be equal to the applied voltage divided by the resistance R. 

Selectivity or Q factor of a series RLC circuit Indicates   that series RLC circuits select a band of frequencies around the resonant frequency, f,. This band (f1 to f2 is called the band width f of the series RLC, circuit.   

Application of series resonance circuits A series resonance circuit can be used in any application where it is required to select a desired frequency. 

Used in wave trap circuits A wave trap is a resonant LC circuit tuned to the frequency to be rejected. 

Used for rejecting unwanted frequencies. 

PARALLEL RESONANCE

The circuit at Fig 1, having an inductor and a capacitor connected in parallel is called parallel LC circuit or parallel. 

resonance circuit. The resistor R, shown in dotted lines indicate the internal dc resistance of the coil L. The value of R will be so small compared to the inductive reactance, that it can be neglected From Fig  it can be seen that the voltage across Land C is same and is equal to the input voltage Vs. 

 Zero current in the circuit means that the impedance of the parallel LC is infinite. This condition at which, for a particular frequency, f,, the value of X, = X,, the parallel LC circuit is said to be in parallel resonance.  

  Zero current in the circuit means that the impedance of the parallel LC is infinite. This condition at which, for a particular frequency, f,, the value of XL = XC the parallel LC circuit is said to be in parallel resonance Summarizing, for a parallel resonant circuit, at resonance  

  In a parallel resonance circuit, with a pure L (no resistance) and a pure C(loss‐less), at resonance the impedance will be infinite. In practical circuits, however small, the inductor will have some resistance. Because of this, at resonance, the  phasor sum of the branch currents will not be zero but will have a small value I. This small current I will be in phase with  the applied voltage and the impedance of the circuit will be very high although not infinite.  

Summarizing, the three main characteristics of parallel resonance circuit at resonance are,  ‐ phase difference between the circuit current and the applied voltage is zero ‐ maximum impedance ‐ Minimum line current. The variation of impedance of a parallel resonance circuit with frequency is shown in Fig 2. 

  Bandwidth of parallel resonant circuits  The bandwidth of a parallel resonant circuit Is also defined by the two points on either side of the resonant frequency at  which the value of impedance Zp drops to 0.707 or   of its maximum value at resonance as shown  the bandwidth of the parallel resonance 

The  selectivity  or  Q‐factor  for  a  parallel  resonance  circuit  is  generally  defined  as  the  ratio  of  the  circulating  branch  currents to the supply current and is given as: 

Application of parallel resonant circuits   

Parallel resonance circuits or circuits. Tank circuits are used as collector load in class‐C amplifiers instead of a resistor  load 

• blocking of freq, filtering 
• selecting of freq  for stability 
• tank  Ckt presents a high impedance to narrow range of frequency.