PASCO WA-9867 Sine Wave Generator - Manual (Page 12)

Sine Wave Generator Applications
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3. Press and hold the Play key to start Auto Play. The speaker will play 120 Hz, 240 Hz, etc., up
to 720 Hz, then repeat.
4. You will notice that the tube does not resonate well above a certain frequency. When the
sequence reaches the highest note that you want, press and hold the Play key. Thereafter, the
sequence will wrap around after that note.
5. Adjust the amplitude of the driving signal with the Amplitude knob.
6. Adjust the duration of each note with the Course (1.0) and Fine (0.1) Frequency knobs.
7. To stop Auto Play, press and hold the Store/Exit key.
Method 2: Scan Across the Fundamental Resonance
1. Using the Frequency knobs, turn the frequency down to 1 Hz. (If you turn the Coarse knob
slowly, the frequency changes by 1 Hz per click; if you turn it faster, the frequency changes by
4 Hz per click.)
2. Press and hold the Store/Exit key to store the increment as 1 Hz.
3. Use the Frequency knobs again to set the frequency to 110 Hz.
4. Press and hold the Play key to start Auto Play. When the frequency reaches 130 Hz, press and
hold the Play key again to make the frequency wrap around and repeat.
5. Use the Frequency knobs to adjust the duration of each note to about 0.5 seconds.
The Sine Wave Generator will now repeatedly scan across the resonance at 120 Hz. Remove the
tube to show that the sound level from the speaker is constant, then put the tube back in place to
show how much louder it gets each time the frequency is near resonance.
Closed Resonance Tube
1. Replace the tube from the previous demonstration with a tube that has one closed end, one
open end, and a fundamental resonance of 60 Hz.
2. Use the Frequency knobs to set the output frequency to the fundamental resonance, then press
and hold Play to make the speaker play 60 Hz, 120 Hz, 180 Hz, etc.
3. Why doesn’t the tube resonate at 120 Hz? This is a good way to demonstrate that closed pipes
only play the odd harmonics.
You can also set up the Sine Wave Generator to play only the odd harmonics.
1. Using the frequency knobs, set the frequency to 120 Hz.
2. Press and hold the Store/Exit key to store the increment as 120 Hz.
3. Use the frequency knobs again to set the initial frequency to 60 Hz.
4. Press and hold the Play key; the speaker will play 60 Hz, 180 Hz, 300 Hz, etc.