Figure 1. Circuit and Parts Bin ToolBars of Electronics Workbench.

Transcription

1 Introduction to Objectives Gain experience with use of circuit simulation software Confirm our theoretical circuit calculations Introduction Start "Electronics Workbench" (or EWB) by double clicking its icon on the desktop or by clicking on Start, then Programs, then Electronics Workbench, and finally the program entry. A window similar to the one in Fig. 1 should appear. In this exercise, you will be oriented to the use of EWB in working with simple dc and ac circuits. For this work, components from four of the parts bins will be used: basic parts, sources, indicators, and instruments. Figure 1. Circuit and Parts Bin ToolBars of Electronics Workbench. Components Clicking on the Basic Parts button of the Parts Bin Toolbar brings up another toolbar containing buttons representing the components contained in that parts bin. Simply clickand-drag any part icon to place a desired part on the circuit workspace. For this exercise, you will rely on the first four parts in the Basic Components Parts Bin: the connection (or node), the resistor, the capacitor, and the inductor.

2 Figure 2. Menu of Basic Components. The first five parts in the Sources Parts Bin are the relevant parts for this exercise: the ground connection, the battery (or dc voltage source), the dc current source, the ac voltage source, and the ac current source. Figure 3. Menu of Source Components. Only the voltmeter and ammeter from the Indicators Parts Bin will be used in this exercise. Figure 4. Menu of Indicator Elements. More sophisticated test instruments such as the multimeter and oscilloscope are available from the Instruments Parts Bin. Figure 5. Menu of Test Instruments.

3 Selecting Components Click-and-drag a resisor from the Basic Parts Bin. The part will appear in red with a specification label in blue. Click-and-drag a second resisor from the Basic Parts Bin. Right click the mouse to bring up its action menu. Select rotate to orient the resistor vertically. Right click the second resistor again and select the components properties menu; change the value of resistance to 2 k. Circuit elements may be moved around the workspace by additional click-and-drag actions. Finally, select a battery for powering the circuit from the Sources Parts Bin. Set the voltage to 12 V if it is not already at that value. Please adjust the display with the Zoom In/Zoom Out tools until the display is comfortable to read. Your workspace should appear something like Fig. 6 at this point. Figure 6. Several circuit elements ready for connection. Connecting Components to Form Circuits Connections among components are formed by click-and-drag actions. When the cursor is directed to one end of a component, a ball will appear when the connector is engaged. Click on the left mouse key when the ball appears, drag a connection to the next component, holding the left mouse key down until a ball appears on the other component. When the mouse key is released, a connection between elements will have been completed as shown below.

4 Figure 7. Three steps in connecting two components. Following the three-step connection process, complete the first circuit as shown. Figure 8. Two resistors in series with a battery. Measuring Circuit Quantities Making measurements with EWB is as easy as selecting and inserting the appropriate

5 displays from the Indicator Parts Bin. Select the ammeter and insert anywhere into the circuit. You may need to break one of the existing connections between components to insert the ammeter. This may be done by moving the cursor to one end of one of the components so that the connection ball reappears, then click-and-drag the wire away from the component, effectively breaking the connection. Insert the ammeter and complete the circuit by remaking the appropriate connections. Figure 9. Ammeter situated to read current in circuit. Finally the simulation is ready to run! Power up the circuit by pushing on the "activate simulation" button in the upper right corner of the EWB window. Observe the current reading. Does it agree with your circuit analysis? Note: you may rotate the ammeter to "fix" the polarity of the reading if you wish... Figure 10. Circuit simulation in operation.

6 Primjeri: Primjer 1: Analogno kolo. Pojačavač-filter I reda sa OP-om. EWB šema Ulazni napon (generator)

7 Oscilogram ulaznog i izlaznog napona. AFK, Bodeov dijagram

8 Primjer 2: Impulsno kolo. Astabilni multivibrator sa 555. EWB šema EWB simulacija, napon na izlazu (OUT) o kondenzatoru (TRI-THR)

9 Primjer 4: Digitalno kolo. 74LS92 kao MOD-16 brojač, koji broji od do Šema čipa i pinout EWB simulacija (ilustracija pomoću lampi)