EEL1010 Experiment 1 Familiarization with Electronic Equipment PDF

Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Aim Familiarization with Laboratory Instruments: Oscillosc...

Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Aim Familiarization with Laboratory Instruments: Oscilloscope, Function Generator, Digital Multimeter, and DC Power Supply Lab Equipment 1. OSCILLOSCOPE Oscilloscope is probably the single most versatile and useful test and measurement instrument invented for electronic measurement applications. It is a complex instrument capable of measuring or displaying a variety of signals. This is the basic equipment used in almost all electronic circuit design and testing applications. The major subsystems in an oscilloscope are power supplies (high and low voltage supplies), display subsystem, vertical and horizontal amplifiers and display systems. There are two major types of oscilloscopes, viz. Cathode Ray Oscilloscopes (CRO) also called Analog Oscilloscopes, and Digital Storage Oscilloscopes (DSO), occasionally called Digital oscilloscopes. There are some analog oscilloscopes which also have the extra facility to store waveforms in digital form; these are called mixed-mode (i.e. Analog/Digital) oscilloscopes. The main use of an oscilloscope is to obtain the visual display of an electrical voltage signal. If the signal to be displayed is not in the voltage form, it is first converted to this form. The signal voltage is then transmitted to the oscilloscope along a cable (usually a coaxial cable) and enters the oscilloscope where the cable is connected to the scope input terminals. Often the signal at this point is too small in amplitude to activate the scope display system. Therefore, it needs to be amplified. Analog Oscilloscope: Cathode Ray Oscilloscope (CRO) In a CRO the X and Y signals are applied to the horizontal and vertical plates, respectively of the cathode ray tube (CRT) after amplification. Within the CRT, an electron beam is created by an electron gun. The electron beam is focused and directed to strike the fluorescent screen, creating a spot of light, where impact is made with the screen. The beam is deflected vertically in proportion to the amplitude of the voltage applied to the CRT vertical deflection plates. The amplified input signal is also monitored by the horizontal deflection system. This subsystem has the task of sweeping the electron beam horizontally across the screen at a uniform rate. A saw tooth type signal (a triangular/ramp signal with long time duration for the rising part of the ramp and very small time duration for the falling part) is internally generated in a CRO as a time-base signal (sweep signal). This signal is amplified and applied to the horizontal deflection plates of the CRO. Again, the beam is deflected horizontally in proportion to the amplitude of the voltage applied to the CRT horizontal deflection plates. The simultaneous deflection of the electron beam in the vertical direction (by the vertical deflection system and the vertical deflection plates) and in the horizontal direction (by the time-base circuitry and the horizontal deflection plates) causes the spot of light produced by the electron beam to trace a path across the CRT screen. For example, if the input signal to the CRO were a sine wave, the trace produced on the CRT screen will be a sine wave. It is important to obtain a stable display on the CRT screen. If the input signal is periodic and the time base circuitry properly synchronizes the horizontal sweep with the vertical deflection, the spot of light will trace the same path on the screen over and over again. For a periodic signal the input signal can be synchronized with the time-base signal using the Trigger controls and the time base controls. If the frequency of the periodic signal is high enough (say greater than 40 Hz), the repeating trace will appear to be a steady pattern painted by solid lines of light on the screen. Page 1 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Digital Storage Oscilloscope (DSO) A DSO samples the input waveform and uses an analog-to-digital converter (or ADC) to convert the voltage being measured into digital information. It then uses this digital information to reconstruct the waveform on the screen. The ADC in the acquisition system samples the signal at discrete points in time and converts the signal's voltage at these points to digital values called sample points. The horizontal system's sample clock determines how often the ADC takes a sample. The rate at which the clock "ticks" is called the sample rate and is measured in samples per second. The sample points from the ADC are stored in memory as waveform points. More than one sample point may make up one waveform point. Together, the waveform points make up one waveform record. The number of waveform points used to make a waveform record is called the record length. The trigger system determines the start and stop points of the record. The display receives these record points after being stored in memory. Depending on the capabilities of the oscilloscope, additional processing of the sample points may take place, enhancing the display. Pre-trigger may be available, allowing you to see events before the trigger point. Fundamentally, with a digital oscilloscope as with an analog oscilloscope, you need to adjust the vertical, horizontal, and trigger settings to take a measurement. Major specifications of the DSO used in the Electronics Lab Model and Manufacturer : DSO 1022A, M/s Agilent Technologies, USA Bandwidth (-3dB) : DC to 200 MHz Vertical range : 2 mV/div to 10 V/div Vertical resolution : 8 bits Real-time sample rate : 2 GSa/s half channel, 1 GSa/s each channel Time-base range : 1 ns/div to 50 s/div Dynamic range : ±6 div DC gain accuracy : 2 mV/div to 5 mV/div: ± 4.0% full scale : 10 mV/div to 5 V/div: ± 3.0% full scale Input coupling : DC, AC and ground Input impedance : 1 MΩ ±1% in parallel with 18 pF ± 3 pF Channels : 2 channels Interface : USB Display : 5.7-inch (145 mm) diagonal color TFT LCD Power consumption : 18 W, 40 VA maximum Dimensions : 341.5 (W) × 162.3 (H) × 159 (D) mm This DSO will be used as measuring equipment for all the experiments. Detailed description of the various subsystems of a CRO/DSO is beyond the scope of this course. Operational details and specifications of the DSO are given at the end. Page 2 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur For more details on different types of oscilloscopes and their applications, you may refer to the following material on the web: “XYZs of Oscilloscopes: Primer”, by M/s Tektronix Inc., USA. URL: http://www.tek.com/Measurement/App_Notes/XYZs/ Figure 1 Basic DSO Operations A schematic diagram of the DSO front panel is shown in Figure 1. Other than the LCD display, there are five major sections on the front panel of the DSO: Section 1 – The five function soft keys and one for menu on/off located on the side of the display. Section 2 – the section below the display consisting of Power switch, and probe compensation output (calibrated source). Section 3 – A variable knob and Ten Menu keys located on the top side to the right of the display. Section 4 – Knobs and buttons located in three different places, indicated as: VERTICAL – near five soft keys, HORIZONTAL - top most, and TRIGGER - right most side of the panel. Section 5 – Located at the bottom part to the right of the display are input BNC sockets for CH-1, CH-2 and External Trigger terminals. DSO operations require the use of a combination knobs and buttons. You need to familiarize yourself well with all the basic operations in order to perform experiments and make measurements using the DSO in the Electronics lab. Page 3 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur a. Channels CH-1 and CH-2 Note that the DSO can display signals simultaneously on Two channels. The signal display part of the LCD screen is 10cm (X-axis) long and 8cm (Y-axis) high. For convenience these channels are indicated with different colors. Signal connected to Channel 1 (CH-1) would appear YELLOW on the LCD screen. Numeral-1 is also indicated on the extreme right side of the display. CH-1 controls are also given yellow color. By pressing the yellow button (CH 1), this channel (and display) can be turned on or off. The volts/div knob indicates the Y-scale in volts/full div or volts/cm. Signal to CH-1 should be connected to the BNC connector seen just below the Volts/div knob. Similarly, the signal to CH-2 should be connected to the socket below the CH-2 volts/div knob. CH-2 display would appear GREEN on the LCD screen. Numeral-2 is also indicated. b. CH-1 and CH-2 Coupling Modes Press the required channel button (CH-1 or CH-2). Now sub-menu for that channel would appear at the left side of the screen. Choose the top option, “Coupling” by pressing the first function key. The current coupling mode would be displayed below the line “Coupling”. The three possible coupling modes are DC (two lines: solid line and broken line), AC (sine wave), and GROUND (ground sign). As you press this function key the coupling modes keep changing. The present mode would be displayed below the “Coupling” function. The most common coupling mode is DC, which would enable you to measure both dc and ac levels of the signal. In the AC mode, the dc content of the signal would be removed. GROUND mode is used to choose the reference zero level for the Y-axis. In this mode DSO disconnects the input signal and connects the channel to ground. c. Triggering the display Proper triggering of the signal is required to get a stable display. When the signal is properly triggered, a message in green color “T’D” would appear on the top otherwise AUTO will appear there. By pressing the “MENU” button in the “TRIGGER” column (extreme right column), various options for triggering are obtained. These are Type: Edge, Pulse, Video Source: CH 1, CH 2, External, Line Slope/Coupling: Slope (+ve/ –ve), Coupling (DC/AC), Rejection (Off/LF/HF), Noise Rej (Off/On) Mode: Auto, Normal For normal use choose Type: Edge, Source: CH1 or CH2, Slope (+ve or –ve), Coupling: DC d. Single and Continuous Trigger Modes The signals to be displayed may be either continuously triggered and acquired by the DSO, or just once. By pressing the “SINGLE” button on the Trigger submenu (extreme right column), signals are acquired just once, the instant immediately after pressing this button. A message “Stop” appears on the top of the LCD display to indicate that the acquisition has been stopped. The trigger mode also turns to “Normal” as indicated at the extreme right bottom. This mode is useful only when you want to make a measurement and are not interested in displaying the input signals in a continuous fashion. Most of the time one is interested in the continuous trigger and acquisition mode. To get back to the continuous mode, press on RUN/STOP. It would make the trigger mode continuous and the “Mode Auto” message would appear at the Page 4 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur lower most function. Now the channels would be continuously updated. The message “T’D” would appear at the top to indicate that the mode is continuous and that the signal is triggered properly. e. Horizontal Functions There are three controls under HORIZONTAL (top most). Last one is the horizontal position knob used to move the display in the X-direction. First one is the “TIME/DIV” knob used to select the time base scale (X-scale). This can range from 10 s/div to 1 ns/div. The current time base scale setting will be displayed at the bottom, a little left to the centre line. A proper setting of the channel Volts/div and Time/div are required to get a clear display. The middle button “MENU” in this column is used to choose the Display mode. f. Display Modes: Main and XY Modes Press the “MENU” button, located in between HORIZONTAL. For normal operations, where you want to display the input signal continuously, the mode should be Y-T base. To get the XY mode, press the XY base key in this menu. XY mode is occasionally used to get the XY plot of the two signals connected to CH-1 and CH-2. In the XY mode, CH-1 signal is taken as the X-axis input and CH-2 the Y-axis. g. AUTOSET Function This button may be thought of as the ‘panic’ button. This button may be pressed when you think that you are lost and needs help (with regard to displaying the signals on the DSO properly!). Once the AUTO button is pressed (extreme top right button) the DSO measures the amplitudes and time periods of the input signals connected to CH-1 and CH-2 and automatically chooses the correct Volts/Div, Time/Div, and Trigger mode settings. 2. FUNCTION GENERATOR Another major equipment commonly used in electronic circuit applications is a Function Generator (FG). As the name indicates, a Function Generator generates different voltage signals, such as Sine, Pulse, Triangle, etc. The most commonly required signals in electronic circuits are Sine and Pulse. Sine wave signals find their use mostly in Analog circuits, such as amplifiers, filters, etc. Pulse signals are useful in testing the time response of circuits and also as Clock signals in Digital circuits. In a general pulse signal, the high and low level time periods are different. Square wave is a special case when the periods are equal. In a FG by the touch of a button one can choose a variety of signals. This is possible because of the fact that one can obtain different signals from a starting signal using wave shaping circuits. The synthesized function generators, the waveforms are generated by digitally stored signals through digital to analog converters. In the Electronics lab you will be using the Model AFG 3021B Function Generator (by M/s Tektronix) which is a 25-MHz function generator. Basic Function Generator (FG) Controls The main purpose of the FG is to give you the signal you require, sine wave, square wave, or triangular wave. You need to choose both the frequency and amplitude of these functions. The FG knobs and buttons explained in Figure 2 would familiarize you as to how you choose a particular function, its amplitude and frequency. Note that the FG output is taken through a coaxial cable from the Waveform Output socket. Page 5 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Figure 2 Front View of the Function Generator The function generator uses Direct Digital Synthesis (DDS) technology to output stable waveforms. In DDS, the waveform data is contained in and generated from a memory. A clock controls the counter for memory addressing. The output of the digital memory is converted to analog signal by a digital to analog converter (DAC) followed by a low pass filter. The information about the type of waveform selected and the frequency are displayed on the display panel of the function generator. a) Waveform Selection Key – This key selects a sine wave, a square wave or a triangular wave. b) Cursor Keys – Moves the editing point left or right in case of manual editing. c) Amplitude–Sets the sine/ square/ triangular waveform amplitude. Turn left to decrease or turn right to increase the amplitude. d) DC Offset Control – When pulled out, sets the DC offset level for sine/ square/ triangle waveform. Turn left to decrease or turn right to increase the offset. The range is -5V to +5 V, in a 50-Ω load. e) Waveform Output – The connector outputs sine, square, and triangular waveform. The output impedance is 50. f) TTL Output – Outputs TTL output waveform (basically 0 – 4 V-pp square wave). Important Note: Do not turn off the DSO or the FG at any time during your experiment. They should be left on till the experiment is over. 3. DIGITAL MULTIMETER The Agilent 34410A digital multimeters (Figure 3) provide 6 ½-digit, high performance dc and ac measurements. Page 6 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Figure 3 Digital Multimeter Features: Voltage and current Measurements (DC and AC - rms) Resistance Measurements (2 and 4 wire) Continuity and diode testing Frequency and Period Measurements Capacitance Measurements Temperature Measurements (Thermistor and RTD) Auto and Manual Ranging Math Features (Null, dB, dBm, limits, and statistics) 4. DC POWER SUPPLY The Scientific Programmable Power Supply PSD9005 is dual DC power supply and delivers fully programmable and remotely-controlled power supply with graphic LCD display. It delivers two DC (0 to 30 V) at 1 A and auxiliary 5V/5A DC output. Both the 30-V DC outputs are independent and isolated. These can be used in tracking mode Master/Slave operation. Page 7 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Experiment 01 Familiarization with electronic equipment इले ॉिनक उपकरणों से प रिचत होना Important terms DSO – Digital Storage Oscilloscope - िडिजटल ोरे ज ऑिसलो ोप FG – Function Generator - फं न जनरे टर EXPERIMENT: Observing signals from the FG on the DSO / DSO पर FG से सं केतों का अवलोकन करना 1. Displaying various functions from the FG on the DSO and understand amplitude and time scales डीएसओ पर एफजी से िविभ काय को प्रदिश त करना और आयाम और समय के पैमाने को समझना (a) Connect the output of the FG to the CH1 of the DSO using two cables and the breadboard. Choose Sine function and adjust the controls to obtain a 5 sin ωt (freq = 10 kHz on the FG). Note that the peak-to-peak voltage of the sine will be 10 Volts. You will need to adjust the Trigger Level controls etc. of the DSO to get a stable display. Measure the time period of the sine wave as accurately as you can using the cursor values (Choose a time-base sweep rate such that the sine wave is well expanded). Also check the frequency reading on the DSO. Sketch and save the waveform. दो केबल और ब्रेडबोड का उपयोग करके FG के आउटपुट को DSO के CH1 से कने कर । साइन फ़ं न चुन और 5 sin ωt (FG पर आवृि = 10 kHz) प्रा करने के िलए िनयंत्रणों को समायोिजत कर । ान द िक साइन का पीक-टू -पीक (peak-to-peak) वो े ज 10 वो होगा। स्थर िडस् े पाने के िलए आपको डीएसओ के िट गर लेवल िनयंत्रण आिद को समायोिजत करने की आव कता होगी। कस र मानों का उपयोग करके साइन तरं ग की समय अविध को यथासंभव सटीक प से माप (एक समय-आधार ीप दर चुन तािक साइन तरं ग अ ी तरह से िव ा रत हो)। डीएसओ पर आवृि रीिडं ग की भी जां च कर । तरं ग प को ेच कर और Save कर । (b) Change the function to Square and Triangle without changing the frequency. Observe and save the waveforms obtained. आवृि बदले िबना फ़ं न को वग और ित्रभुज म बदल । प्रा तरं ग पों को दे ख और Save कर । (c) For sine, square and triangular functions, mentioned in the following Observation Table, verify the measured peak-to-peak value and time period computed using the volt/div and number of divisions covered by the signal. िन िल खत अवलोकन तािलका म उ खत साइन, वग और ित्रकोणीय काय के िलए वो /िडव और िस ल ारा कवर िकए गए िडवीजनों की सं ा का उपयोग करके मापा गया पीक-टू -पीक मान और समय अविध स ािपत कर । Page 8 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur Observation Table 1 / प्रे ण तािलका 1 Waveform No. of Volt/div Measured Actual No. of Time/div Measured time Actual vertical (Vertical peak-to- peak- horizontal (Horz. period (T) = M × Time divisions Scale) peak to-peak divisions in Scale) Horizontal Scale period voltage (N ऊ ा धर वो /िडव voltage one cycle समय/िडव (s) वा िवक × Vertical िवभाजनों की (ऊ ा धर (V) (M) ( ैितज मापी गई समयाविध समयाविध Scale) सं ा (N) पैमाना) वा िवक एक चक्र म पैमाना) (T) = M × ैितज (1/f) मापा गया पीक-टू - ैितज ेल (s) (s) पीक-टू -पीक पीक िवभाजनों की वो े ज (N × वो े ज सं ा विट कल (V) ेल) Sine 10 Vpp f = 10 kHz Square 5 Vpp f = 1 kHz Triangular 2 Vpp f = 500 Hz 2. Effect of Channel Input Coupling Modes (DC and AC modes) चैनल इनपुट कपिलंग मोड (DC और AC मोड) का प्रभाव (a) Set DSO CH1 Input to DC Mode. Choose Pulse Mode and display the FG Function output on the CH1 of the DSO. Set the FG to obtain a Square wave going from 0 to 7V. Adjust the Vertical position of the display such that the 0V level is at the middle of the display. Observe and save the waveform. (Note: In the DC mode of the channel, the signal is connected as it is to the Vertical Amplifier. Hence any DC level already present in the signal is shown in the display also). DSO CH1 इनपु ट को DC मोड पर सेट कर । प मोड चुन और DSO के CH1 पर FG फ़ं न आउटपुट प्रदिश त कर । 0 से 7 V तक जाने वाली एक वगा कार तरं ग प्रा करने के िलए FG सेट कर । िडस् े की ऊ ा धर स्थित को इस प्रकार समायोिजत कर िक 0 V र िडस् े के म म हो। तरं ग प का िनरी ण कर और सहे ज । (नोट: चैनल के DC मोड म , िस ल वैसे ही जुड़ा होता है जैसे यह विट कल ए लीफायर से होता है । इसिलए िस ल म पहले से मौजूद कोई भी DC र िडस् े म भी िदखाया जाता है )। (b) Switch the CH1 input mode to AC. Observe and save the change in the display. Explain the result. (Hint: In the AC mode, the DSO inserts a Capacitor in series with the signal before connecting it to the Vertical amplifier). CH1 इनपुट मोड को AC पर च कर । िडस् े म प रवत न को दे ख और Save कर । प रणाम कर. (Hint: AC मोड म , DSO विट कल ए लीफायर से कने करने से पहले िस ल के साथ श्रृंखला म एक कैपेिसटर डालता है ) 3. X-Y Plot using DSO One of the useful features in a modern DSO is the facility of XY Plot. This facility can be used to display the output waveform of a circuit as a function of the input signal. आधुिनक DSO म उपयोगी सुिवधाओं म से एक XY ॉट की सुिवधा है । इस सुिवधा का उपयोग सिक ट के आउटपुट तरं ग को इनपुट िस ल के फ़ं न के प म प्रदिश त करने के िलए िकया जा सकता है । (a) Adjust the FG and display 5 sin ωt (freq = 1 kHz on the FG) on CH1. Put the CH1 and CH2 input modes to GND. Put the scope in X-Y mode. Adjust the X and Y positions of the display so that the dot displayed on the Page 9 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur DSO is located at the origin in the middle of the LCD display. FG को समायोिजत कर और CH1 पर 5 sin ωt (FG पर आवृि = 1 kHz) प्रदिश त कर । CH1 और CH2 के इनपुट मोड को GND पर रख । ोप को X-Y मोड म रख. िडस् े की ए और वाई स्थित को समायोिजत कर तािक डीएसओ पर प्रदिश त िबंदु एलसीडी िडस् े के म म मूल स्थान पर स्थत हो। (b) Now remove the GND modes and choose DC modes for both CH1 and CH2. Connect the sine wave signal to both the channels. Observe the waveform and save it. What is the shape of the X-Y plot? Note the slope of this X-Y plot (Slope is the ratio of Y and X intercepts) अब GND मोड हटाएं और CH1 और CH2 दोनों के िलए DC मोड चुन । साइन वेव िस ल को दोनों चैनलों से कने कर । तरं ग प का िनरी ण कर और इसे Save कर । X-Y ॉट का आकार ा है ? इस X-Y ॉट की ढलान पर ान द (ढलान Y और X इं टरसे का अनुपात है ) (c) Use a simple potential divider using two 10 k resistors as shown in Fig. 5. Connect the FG to CH1 (as X) and the potential divider output to CH2 (as Y). Observe and save the waveforms. What is the slope of this new X- Y plot? जैसा िक िचत्र 5 म िदखाया गया है , दो 10 k प्रितरोधों का उपयोग करके एक सरल सं भािवत िवभ का उपयोग कर । FG को CH1 (X के प म ) और संभािवत िवभ आउटपुट को CH2 (Y के प म ) से कने कर । तरं ग पों का िनरी ण कर और उ Save कर । इस नये X-Y ॉट की ढलान ा है ? Vin (to CH 1) 5 sin 2πft (for f = 1 kHz) V0 (to CH 2) Figure 5 Circuit diagram of the potential divider िचत्र 5 संभािवत िवभ का सिक ट आरे ख Observation Table 2 प्रे ण तािलका 2 Case Shape of the X-Y Plot Slope of the X-Y plot X-Y प्लॉट का आकार X-Y प्लॉट क ढलान When both X and Y are 5 sin ωt जब X और Y दोनों 5 sin ωt हों When X is 5 sin ωt and Y is the output of potential divider (Fig. 5) जब X 5 sin ωt है और Y संभािवत Page 10 of 11 Experiment 01 EEL1010 Introduction to Electrical Engineering Familiarization with Electronics Lab Instruments Department of Electrical Engineering, IIT Jodhpur िवभाजक का आउटपुट है (िचत्र 5) Multimedia Content R. Chouhan, "Working with Function Generator, DSO, and Breadboard,” Basic Electronics Video Lectures, https://youtu.be/WjqA0KW3oks, 2018. Page 11 of 11