Question

1. Read the laboratory supplement entitled “Frequency Response". 2. Read the remainder of this handout. 3. In Multisim, build the circuit shown in Figure 1 with C=0.22 uF and R = 2.2 k12. This circuit looks like a simple voltage divider except that one of the resistors is replaced by a capacitor. Il Figure 1: RC network. F Set up Vin to be a 1 Vpp sinusoid with 0 VDC Offset using a function generator. 2. Connect the oscilloscope in Multisim to monitor both Vin and you. 3. Measure the magnitude of Vin and you for frequencies of 20 Hz, 50 Hz, 100 Hz, 200Hz, 300 Hz, 400 Hz, 500 Hz, 600 Hz, 800 Hz, 1 kHz, 2 kHz, 3 kHz, 5 kHz, 10 kHz, 20 kHz. 4. Plot the magnitude of you (in Vpp) vs. frequency (Hz) for all of the frequencies above. You should observe that the magnitude of the output signal changes as the frequency changes. This is very different than what would happen in a purely resistive circuit. 5. This type of circuit is called a filter - it filters out (removes/attenuates) certain frequencies while allowing other frequencies to pass through (remain). A low-pass filter is a filter that attenuates signals with frequencies higher than certain cutoff frequency and passes low- frequency signals. In the range of audio frequencies we can think of such a filter as a "treble cut” filter. A high-pass filter on the other hand passed the frequencies higher than cut off frequency and attenuates Ver. A low frequencies and thus acts as a "bass cut" filter. Based on you results above, which kind of filter is this particular filter?

Answer 1

The circuit is wired as follows

XSC1 Tektron O O R1 2.2kQ XFG1 C1 +G c0.22uF IG ОЛЛ чо- 모마- WO

Now the input frequency is changed using the function generator and the output voltage is noted for the given frequencies

Vout Vin Frequency f, (Hz) Peak to peak Voltage (Vpp Peak to peak Voltage (Vpp Sl. No (V) (V) 1 20 0.999 0.992 2 50 0.999 0.981 100 3 0.999 0.951 0.995 4 200 0.849 0.998 300 0.734 6 400 0.989 0.623 0.543 7 500 0.988 0.984 8 600 0.472 0.996 800 0.374 0.994 10 1000 0.308 0.981 11 2000 0.160 12. 3000 0.994 0.105 0.995 13 5000 0.0647 14 10000 0.984 0.0319 15 20000 0.999 0.0162

The graph was then plotted.

Frequency Response 1.2 0.8 0.6 0.4 0.2 0 5000 10000 15000 20000 25000 Frequency (Hz) Ouput Voltage (V)

From the graph, we can say that the circuit behaves as a low pass filter as it passes low frequencies and stops high frequencies