Saturday, March 28, 2009

Ultrasonic Sensor Circuit 3

Arduino + Ultrasonic sensor + MP3

In this project for
Martí Guixé we built a small autonomous device
Arduino that can detect the presence of people with an
ultrasonic sensor. It then proceeds to play an MP3 song with a
Yampp Industrial II

Ultrasonic range finder uses few components

Measuring distance with ultrasonic signals requires a transmitting
ultrasonic transducer; a medium, such as air or water; a reflecting
surface or object; a receiving ultrasonic transducer; and a
time-of-flight measurement circuit. The speed of sound in air at
20 C is approximately 343m/sec, which translates to about 1 in. Per
74 Wsec. Doubling the time gives you the round-trip speed, which
is 1 in. per 148 Wsec. Four aspects of the system limit the
maximum measurable distance: the amplitude of the sound wave,
the texture of the reflecting surface, the angle of the surface with
respect to the incident sound wave, and the sensitivity of the
receiving transducer. The receiving transducer's direct reception
of the sonar pulse—and not the echo—usually dictates the
minimum measurable distance.

Circuit drawingfor Ultrasonic Range Meter

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