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Periodic Phenomena
Kundt's tube with analog outputs
Ref : 22204
The control unit contains the electronic device that powers the electret-condenser
microphone and processes the signals detected (amplification, rectification and peak
value). The microphone's position sensor is also placed in this box; it provides a DC
voltage, image of the abscissa of the microphone in the pipe. The origin corresponds to
the left end of the sound pipe.
Additional equipment required (not supplied):
2. Objectives
Kundt's tube is designed to study the vibratory states of air contained in a pipe when sound
waves are generated.
The device helps detect the pressure nodes and antinodes created by the loudspeaker in
the air column with the electret-condenser microphone.
3. Processing detected signals
The tube has two sensors:
3.1
This signal is used in 2 ways:
3.2
The electret-condenser microphone moves in the sound pipe with the help of a control rod
link that slides in the control unit. On its passage, the tube drives a gear wheel coupled to
the axis of a potentiometer.
The output
To calibrate the system, place the microphone in front of the zero of the graduated scale
(facing the end of the tube opposite the loudspeaker) then record the voltage in Généris 5.
ENGLISH
•
Signal generator
•
ESAO 4 console + Généris 5 Software
Or
•
JO20 oscilloscope
•
One of them provides information about the vibratory state generated at one point
of the pipe by a sound wave
•
The other marks the position of the previous sensor inside the pipe
Signal detected by the microphone
•
The output
consists of the actual instantaneous signal that can easily be observed on an
oscilloscope.
•
The output
raw signal. This output is mainly used with an ExAO system but it can also be used
with an oscilloscope or a multimeter (the recording of the voltage in function of the
position of the microphone is done manually).
Signal giving the abscissa of the microphone
x gives the position of the microphone in the tube.
gives the "raw" signal detected by the microphone. This
provides a DC voltage that is the envelope of the rectified
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