Notes on Lab 1 Introduction to Circuits | ECEN 3010, Lab Reports of Electrical and Electronics Engineering

Download Notes on Lab 1 Introduction to Circuits | ECEN 3010 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! ECEN 3010 Lab Circuits and Electronics University of Colorado at Boulder Lab #1 Introduction to Circuits Names of All Participating Lab Partners: Lab Section (Circle One): M T W Th F Learning Objectives This lab will acquaint you with lab equipment and breadboarding basics. It will also introduce you to several electronic components. Minimum Parts Required One each of LM555 and 2N3904; an LED; various resistors and capacitors. Part 1 – The Oscilloscope and the Function Generator The function generator is a voltage source that creates AC waveforms (sinusoidal, sawtooth, and square wave functions) over controllable ranges of frequency and amplitude. The oscilloscope (“scope”) is an instrument that lets you view voltage versus time. Complete the following exercises using the function generator and oscilloscope. 1.1) Turn on the function generator and the oscilloscope. Use a BNC cable and banana adapters to connect the function generator output to the breadboard terminals. See Figure 1 and Figure 2. The center conductor of the BNC connector (or red clip lead) is the “positive” terminal of the function generator output; the outer conductor (or black clip lead) of the BNC connector is the “negative” or “ground” terminal of the function generator. Use the black breadboard terminal as the ground (reference node) of your circuit. ECEN 3010 Lab 1 Page 1 of 10 Rev. 2008-08-24 This material is subject to copyright notice on last page. Figure 1. Breadboard terminals with banana plugs connected. v(t) Oscilloscope Probe+ – Breadboard Terminals Function Generator Breadboard Any two separate nodes BNC/Banana Cable Figure 2. Connections between the function generator, breadboard, and oscilloscope are shown. 1.2) Connect a jumper wire from the function generator breadboard terminal to a node of your choosing on the breadboard. Connect a scope probe to Channel 1 of the oscilloscope. Use the oscilloscope probe to view the voltage waveform at the node on the breadboard; do this by connecting the center pin of the probe to the node, and by connecting the ground clip lead of the probe to your circuit ground. 1.3) Use the function generator to produce a square wave with the following characteristics: Amplitude: 5 V (peak-to-peak) Frequency: 20 Hz Voltage Offset: 2.5 V (so that the waveform ranges from 0 V to 5 V) 1.4) Use the scope view the waveform (see Note 1 and Note 2 on the following pages). Adjust the time scale (seconds/division) (horizontal) on the scope so that you have two complete waveform periods on the scope screen. Adjust the oscilloscope voltage scale (volts/division) (vertical) so that you see the top and bottom of the waveform on the screen. Do this without using the autoscale feature of the oscilloscope. ECEN 3010 Lab 1 Page 2 of 10 Rev. 2008-08-24 This material is subject to copyright notice on last page. Figure 4. The collector (C), emitter (E), and base (B) pins of the transistor are shown in the diagram. Anode Cathode Figure 5. The anode and cathode of the LED schematic symbol are indicated as shown. The anode of the physical component has a longer lead. Figure 6. Your circuit might look something like this. ECEN 3010 Lab 1 Page 5 of 10 Rev. 2008-08-24 This material is subject to copyright notice on last page. 2.2) Use a second scope probe to measure the voltage at the collector (C) of the transistor. Compare the voltage waveform at the base the circuit with the voltage waveform at the collector. Are they different? If so, how? 2.3) Change the frequency on the function generator to 1 Hz. Can you see the LED flash? 2.4) Change the frequency on the function generator to 1 kHz. Can you see the LED flash? If not, why would you not be able to see the flashing of the LED? ECEN 3010 Lab 1 Page 6 of 10 Rev. 2008-08-24 This material is subject to copyright notice on last page. Part 3 – Generating a Square Wave with an Astable Multivibrator Circuit You will not always use the function generator to generate waveforms. For this part of the lab, you will use an LM555 integrated circuit timer to generate a square wave signal. You will use this square wave voltage signal as the input to the LED-flashing circuit you built earlier in this lab. 3.1) Build the astable multivibrator circuit in Figure 7. This circuit will produce a 0 to 5 V square wave. The frequency will be determined by a resistor and capacitor values you use in this circuit. The LM555 IC is shown in Figure 8. It is ALWAYS good practice to put capacitors between power (Vcc) and ground (GND) pins of an integrated circuits. You will learn about this later in the course. Although not shown in the schematic, be sure to put a 0.1 uF capacitor between Vcc (power) and GND (ground) near the LM555 IC. The 0.1 uF capacitors are the mustard-colored beads with the label “104”; 104 means 10x10^4 pF. C1 6.9u R2 4.7k U1 555 1 2 3 4 6 7 8 5 GND TRG OUT RESET THRHLD DISCHG Vcc CV +5 V R1 1k To input of LED circuit Square-Wave Output LM555 Integrated Circuit (IC) Figure 7. This astable multivibrator produces a square wave. ECEN 3010 Lab 1 Page 7 of 10 Rev. 2008-08-24 This material is subject to copyright notice on last page.