The use of virtual function signal generator in Multisim

When doing experiments, a function signal generator is used as a signal source. This section introduces the use of virtual function signal generator.

1) Place the virtual function signal generator on the working platform

Open the document "Series Circuit 1" and delete the voltage source on the workbench. Place the mouse on the second icon below the multimeter icon on the right border of the workbench. "Function generator" is displayed. This is a virtual function signal generator. The operating steps are the same as for a multimeter. Click this icon, and the function signal generator appearance will be displayed on the front end of the mouse, indicating that the instrument has been picked up. Move the mouse to a suitable position on the work platform and click the left mouse button again to place the function signal generator at this position.

Virtual function signal generator usage

There are three terminal buttons on the function signal generator icon: "+", "-" and the ground terminal in the middle. Connect the positive terminal and the middle "ground" terminal of the virtual function signal generator to both ends of the 1KΩ resistor respectively, and connect the "ground" terminal to the ground. The circuit is as shown in the figure. After clicking the "Run" button, double-click the function signal Generator icon, the "Function generator-XFG1" dialog box appears. This is the panel of the function signal generator, as shown in Figure 1.

Figure 1 Virtual function signal generator panel

At the top of the panel are the three waveforms that the function signal generator can generate: sine wave, triangle wave and square wave. Below it is the signal parameter setting, which can set the signal frequency, duty cycle, amplitude, and bias voltage. Now select a sine wave signal with a frequency of 50Hz and an amplitude of 141.4V.

Because the running results also require a multimeter for measurement, add a multimeter to the work platform, select the AC voltage range or current range, connect in parallel or series, and check whether the displayed results are the same as the previous "Series Circuit 1" test results.

The virtual function signal generator can provide both positive and negative polarity power.

Connect the positive and negative polarity ends of the function signal generator to both ends of the resistor respectively, as shown in Figure 2. At this time, you will find that the amplitude of the sinusoidal AC signal output by the signal generator is 141.4V, that is, when the effective value is 100V, the voltage The voltage measured by the meter is 200V. The reason is that the virtual function signal generator has dual power supplies, and what is displayed on the panel is the voltage to the common terminal (ground) in the middle. Now the input voltage between the positive and negative power supplies is twice the displayed voltage.

Figure 2 Virtual function signal generator dual power supply

summary:

The virtual function signal generator is equivalent to a voltage source in the circuit;

The virtual function signal generator is a dual power supply, usually in a circuit, and its output end is connected between the "+" or "-" polarity end and ground.

The circuit also needs to be "grounded", otherwise the display will be wrong.

If you want to display the waveform of an AC signal, you need to use an oscilloscope.