Electronic WorkBench tutorial

Introduction

Electronic WorkBench (EWB) is a simulation package for electronic circuits. It allows you to design and analyze circuits without using breadboards, real components or actual instruments. EWB's click-anddrag operations make editing a cir

cuit fast and easy. You can change parameters and circuit components on the fly, which make "what-if" analysis straight foreward.

This tutorial is intended as a quick introduction to E

WB's basic features. It first leads you through the fundamental steps of putting a circuit together and analyzing its function using the instruments. The final part of the tutorial consists of two exercises that try to illustrate the

power of EWB. It also tries to encourage you to apply the "what if" approach to circuit design. It will greatly help your understanding of electronics

if you use EWB in an interactive manner: Make change to the circuits you are working on, observe the effects that these changes have,

and try to understand them. EWB puts very little constraints on parameters so do not be too timid, don't just change things by 10%, try out what happens when you change them by a couple of orders in magnitude.

Directly printing EWB schematics and graphs does usually not produce satisfactory result, and leads to a tremendous waste of paper. It is bette

r to incorporate EWB results by copying them to the clipboard using the copy as bitmap command, and then pasting this into a something like a word document.

Directly printing EWB schematics and graphs does usually not produce satisfactory result, and leads to a tremendous waste of paper. It is better to incorporate EWB results by copying them to the clipboard using the copy as bitmap command, and then pasting this into a

something like a word document.

To open EWB click on its icon. Initially you will see an empty circuit window and two toolbars, the circuit toolbar with the common file ma

nagement, editing and graphics tools, and a Parts Bin toolbar from which you can select a wide range of circuit elements, and instruments. The following will guide you on your first attempt to simulate circuits.

Building and testing a circuit

In this part of the tutorial, you will build the simple DC voltage divider circuit shown below.

Figure 1. A resistive voltage divider

Step 1. Place the components on the circuit window

To build the circuit, you need a battery, two resistors and a ground connection. Assemble the components for the circuit.

1. Choose File/New to open a new circuit file.

2. Click in the Parts Bin toolbar. The basic toolbar should appear.

3. Drag two resistors from the toolbar to the circuit window.

To keep the Basics toolbar open, drag it onto the circuit window. Otherwise, it will close after you drag an item from it, and you will have to reopen it for every resistor.

4. Move to the Sources on the Parts Bin toolbar. Click on it and a toolbar containing the battery and ground should appear. Drag those onto the circuit window.

Step 2. Arranging the circuit elements

You can change the orientation of the circuit elements either by rotating them or flipping them over. To do this, select the circuit element and either click on the standard rotated/flip icons on the toolbar, or select the desired operation under Circuit. In this case you want to rotate both resistors.

1. Select both by either CTRL+click, or by dragging the mouse over them.

2. Choose your favorite way to rotate by 90 degrees.

Note that selected circuit elements are highlighted/changed color.

Step 3. Wire the components together

Most components have short lines pointing outwards, the terminals. To wire the components together you have to create wires between the components.

1. Move the pointer to the terminal on the top of the battery. When you are at the right position to make a connection, a black dot appears. Now drag the wire to the top of the upper resistor. Again a black dot appears, and the wire snaps into position.

2. Wire the rest of the components in a similar manner. You should end up with something like this:

Initially you wiring may not look very pretty. However, after making the connections, you can move wires and components around without breaking the connections.

Step 4. Set values for the components

Initially, each component comes up with a pre-set, default value, e.g., the battery voltage is set to 12 V. You can change all component values to suit your application.

1. Double-click on the component.

2. Select VALUE

3. Change its value.

4. Click OK.

Step 5. Save your circuit

Save your work frequently!

1. Select File/Save.

2. Proceed in the normal way for saving files.

Step 6. Attach the voltmeter

To measure voltages in your circuit you can use one or more voltmeters.

1. Drag a voltmeter from the indicator toolbar to the circuit window.

2. Drag wires from the voltmeter terminals to point in your circuit between which you want to measure the voltage.

3. Activate the circuit the circuit by clicking the power switch at the top right corner of the EWB window.

Step 7. Make changes and additions

You now have a very simple but functioning circuit. Take this opportunity to make some changes and additions.

1. Add an ammeter to the circuit to measure the current through the resistors.

2. Change the values of the resistors, and observe the change in the currents and voltages.

The ammeter can be connected by positioning it on top of the wire through which you want to measure the current. EWB will automatically make the right connections. If you are not sure that this is done correctly, drag the ammeter, the wires should move with it.

Note that the ground connection plays no particular role in this measurement. The voltmeter is not connected to a reference point. It functions very much like the hand-held multimeter in the lab. You can measure voltage differences between any pair of points in the circuit.