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Laboratory 1 Instruments and probes. EDA tools: electronic circuits simulation using Proteus and  Multisim.

Lab2 [13/2]

1. Specifications

Our goals are:

(1) Install and license commercial software: Proteus,  Multisim and Ultiboard in your portable computer.

(2) Install free apps: Arduino IDE and VB8012 VirtualBench.

(3) Install an enriched text editor such Notepad++

Fig. 1. Software applications icons.

(4) Run demonstration applications to check that the software is installed and operating correctly.

(5) Modelling probes and study how to represent the equivalent circuit of typical instrumentation. Measuring voltages, currents. Bandwidth.

This is an individual project, each student must have the specified EDA tools running correctly in its portable computer.

 

2. Planning

(1) Find where to download each application and where to find licences as an UPC-EETAC student. Proteus is available at our shared Drive.

(2) Run demo projects and print examples, checking at the same time that your software installations is correct.

 

3. Development and (4) Testing

Develop 

1. Install Proteus as indicated using our cloud license server.

2. Download and install the default Arduino integrated development environment (IDE).

Fig. 2. Arduino IDE opening window. The current version is 2.03.

3. Install Notepad++. You can also install a plugin for detecting spelling errors in several languages.

Fig. 3. Notepad++ and its spelling checker plugin.

4. Install and license Multisim and Ultiboard. How to proceed and licence it is explained in this EETAC page.

Fig. 4.  Multisim education to download.  Multisim and Ultiboard opening windows. Both applications will work concurrently on the design of schematics and their printed circuit boards.

Activate the software using licence numbers supplied from the UPC.

Fig. 5. With NI license manager you can activate your NI software using our UPC licenses.

 

5. Install VB8012 Virtual Bench instrument driver.

Fig. 6. With NI license manager you can activate your NI software using our UPC licenses.

 

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Testing

Once installed, most of the applications contain demo designs and projects that can be used for verifying that the software works correctly.

Verifying Proteus installation.

Fig. 7. Example of hardware and software project development and debugging environment in Proteus, simulating Microchip PICDEM2 training board.

Verifying  Multisim and Ultiboard. Explore sample projects and check how schematics and PCB windows are working concurrently. For instance open a new folder in your C drive "C:\EMC\LAB1\Getting_Started" and unzip this file  Getting_Started.zip. Open the project file that contains both the schematic and the PCB. Keep both windows synchronised using net file transfers.

Fig. 8. Sample project (extension .mp14) for Ultiboard PCB (extension .ewprj) and  Multisim schematic (extension .ms14).

 

Verifying VirtualBench instrument.

Check that the appications detects the USB instrument and characterise and print an acquisition of the reference squared signal.

Fig. 9.

 

5. Prototyping

Prototyping using training boards is the previous step before designing custom printed circuit boards (PCB).

Fig. 10. Example: basketball scoreboard system prototype.

Find similar examples of prototypes in internet.

Prototyping is practised all the time when using Arduino and other training boards environments. As an example browse this page on Arduino Prototype to Manufacturable PCB: An LED Multiplexer, by Thomas Nabelek, 2016.

 

6. Reporting

Studying and reporting this LAB1 means having been able to install, license and run the EDA tools in your portable computer. Your report contains at least five sections of handwritten sheets of paper and printed images from circuits.

(1) Specifications. Install the software applications indicated.

(2) Planning. List of operations for installing a given software

(3) Developing. Show some circuits captured. Show how you have translated some flowcharts to Arduino C code.

(4) Testing. Run, print and comment some schematics and simulations.

(5) Prototyping. Print and example schematic and PCB from Multisim and Ultiboard. Print some waveforms captured from the VirtualBench instrument.

 

NOTE: Be aware that for printing you must change the black background colour to white so that your printed does not waste ink.

 

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Class discussions:  Modelling and using oscilloscope probes.

Fig. 1. The electrical equivalent of an oscilloscope measurement probe. (picture ref.).

Draw the electrical equivalent circuit of the function generator connected to the oscilloscope using a probe. Find in datasheets and user guides the capacitor values (for instance the PS2150 probe))and calculate at which sinusoidal frequency the voltage at the oscilloscope drops 3 dB for the probe at a) 1:1 and b) 10:1.

a) Passive probe 1:1. Voltage gain (attenuation) and -3 dB bandwidth (BW).

Fig. 2. Bandwidth calculation for the 1:1 probe, basically a simple coaxial cable.

Demonstrate the formula relating BW-3dB and rise time.

Fig. 3. Rise time and BW-3dB relation modelling a capacitive first order simple RC circuit at the oscilloscope input.

 

b) Passive probe 10:1. Voltage gain (attenuation) and -3 dB bandwidth (BW).

Calculate components and trimmer values  for compensating capacitive effects over frequency.  Use real data from probe datasheets to generate values.

Fig. 4. Approximate equivalent circuit and analysis of a typical passive prove in 10:1 configuration.

Calculate the 10:1 probe new bandwidth (BW-3dB) and compare with probe 1:1

Fig. 5. Bandwidth calculation for the 10:1 probe modelling the same first order capacitive circuit. We pay the price of derating the voltage gain from 0 dB to -20dB, but we can use the probe at much larger frequencies.

 

Example verification simulations using Proteus. Here it is easy introducing second order effects like wire parasitic inductances (LP) and visualise what happens when modelling 10:1 and 1:1 probes, using both sinusoidal and pulsed waveforms.

Do not start a circuit from scratch but use and adapt this sample oscilloscope_probe.pdsprj.

Fig. 6. Example of simulation trimming the compensation capacitor CP in the probe block. Try CP = 75 pF, Rg = 1 W. Try LP = 10 pH (practically zero inductive effect) and observe the waveforms.

 

Perform the same simulation experiment in  Multisim. 

 

Class Activities:  

Consider measuring v0(t) and i0(t) in the Fig. 7 circuit using an oscilloscope. Use (a) ideal probe, (b) 1:1 probe, (c) 10:1 probe. Apply simplifications, equivalent models or whatever techniques you remember from previous subjects. Calculate the relative error for each probe.

w = 2pf;  f = 1 MHz.

 option #1: vin(t) = VA sinwt; VA = 5 V; R1 = 300 W; R2 = 820 W; R3 = 1.8 kW; R4 = 2.7 kW

 option #2: vin(t) = VA sinwt; VA = 3.3 V; R1 = 47 W; R2 = 86 W; R3 = 180 W; R4 = 330 W

 

Fig. 7. Circuit with resistors.

 

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Topics in EMC

Simulate an AC noise source at the generator end (Vt) with (1) capacitive coupling and (2) inductive coupling.

 

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