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| university:courses:electronics:electronics-lab-speaker [14 Feb 2013 20:10] – [Procedure:] Doug Mercer | university:courses:electronics:electronics-lab-speaker [28 Feb 2013 16:06] – [Procedure:] Doug Mercer | ||
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| - | Start the Waveforms software. On the More Instruments menu select the Network Analyzer instrument. Under the Scope Channels controls unselect the Use Channel 1 as Reference. Set the start frequency to 10Hz and the end frequency to 1KHz. Set the amplitude to 2 Volts and the offset to 0V. Set the max gain to 1X. Under the Settings drop down tab open the options window and set the settle time to 40 and the FFT window to cosine. Hit the green Run Single button. You should see the frequency response of the voltage across the loudspeaker and the current through the speaker (by measuring the voltage across the 100 ohm resistor). The data on the screen is plotted in dB so the vertical scale is not in volts. An example plot is shown in figure 3. Your speaker will probably look much different than this. | + | Start the Waveforms software. On the More Instruments menu select the Network Analyzer instrument. Under the Scope Channels controls unselect the Use Channel 1 as Reference. Set the start frequency to 10Hz and the end frequency to 1KHz. Set the amplitude to 2 Volts and the offset to 0V. Set the max gain to 1X. Under the Settings drop down tab open the options window and set the settle time to 40 and the FFT window to cosine. |
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| + | A few words on why these setting should be adjusted. As the frequency is swept the AWG output is stopped briefly between frequency steps and the signal driving the speaker will be turned off. The speaker is a mechanical system with resonance and this step change in the driving signal will cause it to ring at the resonate frequency. In order to make an accurate measurement at the driving frequency we must wait for the ringing to die out. The amount of time needed will depend on the particular speaker being measured. The 40 mSec suggested above was the correct value for the speaker used in this example. Your results may vary depending on your particular speaker. Switching to the cosine window function gives a more accurate amplitude result. | ||
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| + | Hit the green Run Single button. You should see the frequency response of the voltage across the loudspeaker and the current through the speaker (by measuring the voltage across the 100 ohm resistor). The data on the screen is plotted in dB so the vertical scale is not in volts. An example plot is shown in figure 3. Your speaker will probably look much different than this. | ||
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university/courses/electronics/electronics-lab-speaker.txt · Last modified: 05 Apr 2023 18:43 by Doug Mercer