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EWB

Electronics Workbench Circuit Simulation

In this tutorial, several example circuits from this chapter are simulated in EWB using multiSIM andthe results compared to the calculated results. Verifications of several circuit theorems areillustrated. In the exercises at the end of the tutorial, you will construct other circuits and run thesimulations. In this tutorial, you will

Construct EWB circuits

Use EWB measurements to verify the superposition theorem

Use EWB measurements to verify Thevenin's theorem

Use EWB measurements to verify orton's theorem

Example 8-1This e!ample sho"s that the measured current throu#h R$ in te!tbook %i#ure &()a#rees "ith the calculatedvalue that "as determined by applyin# the superposition theorem*

Figure 8-1

Solution The measured value of the current throu#h R$is +(,*+ -* This small ./*012 difference from the

calculated value of +/3 is because of roundin# in each step of the calculation*

SimulationConnect the circuit in %i#ure &/ and run the simulation*

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Example 8-2This e!ample illustrates the measurement of Thevenin volta#e and resistance for the circuit in te!tbook%i#ure &$$and the resultin# e4uivalent circuit*

Figure 8-2

SolutionThe measurements of VTHand RTHa#ree "ith those calculated in te!tbook E!ample &/3*

SimulationConnect the ori#inal circuit in %i#ure &( and run the simulations to measure VTHand RTH*

5emove the voltmeter and connect a /33 load resistor bet"een points - and B in both the ori#inal circuit

and the e4uivalent circuit* -lso connect an ammeter and verify that the current in the load is the same for theThevenin e4uivalent circuit as it is for the ori#inal circuit*

Example 8-3This e!ample illustrates the measurement of the orton e4uivalent current for the circuit in the previouse!ample and a comparison of the e4uivalency of Thevenin6s and orton6s circuits*

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Figure 8-3

Solution The orton current for the circuit is (&*++ m- as sho"n in the measurement in the circuit at the left*The orton resistance is the same as the Thevenin resistance found in the previous e!ample* The t"oe4uivalent circuits at the ri#ht sho" that "hen the same load resistance is connected to both the Theveninand the orton circuits7 the load current is the same7 /)*+, m- in this case* This illustrates that they aree4uivalent to each other as "ell as to the ori#inal circuit* The dc current source is available in the Sourcesparts bin*

SimulationConnect the circuit in %i#ure &$ and run the simulation* Then7 place a /33 load resistor in

series "ith the ammeter in the ori#inal circuit* 8ou "ill observe that the current throu#h the load is /)*+, m-7"hich is the same as in each of the e4uivalent circuits*

EWB Exercises

1. Connect the circuit in %i#ure &$ and measure the output volta#e for R9: ,)3 and for R9: / k;*

Compare the measurements "ith the calculations in te!tbook E!ample &/*(* Connect the circuit in te!tbook %i#ure &(3and measure the current throu#h R(* Compare the result

"ith the value determined in te!tbook E!ample &0*

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