Copyright © Parallax Inc.
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The Sound Impact Sensor is particularly sensitive to loud and abrupt low frequency (under 500
Hz) sound, such as a hand clap. The sensor can also detect the sound caused when something
strikes against it (or whatever object the sensor is fastened to). You can use this feature, for
example, as an obstacle detector on a small robot.
Parts List
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Sound Impact Sensor
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BASIC Stamp HomeWork Board, Propeller BOE, Propeller QuickStart, or Arduino Uno
microcontroller (solderless breadboard as needed)
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22 gauge solid conductor hookup wire
Basic Wiring
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Power requirements: 5 VDC*
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Communication: Single bit high/low output
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Dimensions: 0.6 x 1.5 in (15 x 38 mm)
* The signal output of the Sound Impact Sensor incorporates a series resistor, allowing it to be
directly interfaced to the Propeller, which operates at 3.3 volts. For best results be sure to power
the sensor at its rated 5 volts, even when connecting it to the Propeller.
Program KickStarts
Each of the example programs displays the current state of the Sound Impact Sensor in a
terminal/debug window. Sound that exceeds the adjusted sensitivity of the sensor produces a
momentary HIGH output on the SIG(nal) pin. In each program the output of the sensor is
checked every 100 milliseconds (1/10th second).
A red LED on the sensor blinks on whenever it has detected a loud sound. Once the sound level
falls below the adjusted sensitivity, the sensor resets itself and the LED goes out.
