Sensors

Accelerometers, Gyroscopes, Temperature Sensors, Pressure Sensors, ...

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Accelerometer

These measure ( gasp ) acceleration. May be caused by gravity or the second derivative of position ( relative to an inertial frame ). Since acceleration is a vector to go the whole distace you need a 3 axis sensor, but often 1 or 2 D will do. Often the output is a voltage(s). Feed it to a microcontroller with an a to d converter, perhaps through an operational amplifier. Op amp

• Accelerometer 101: Understanding the Nike iPod Sport Kit Sensor

• Accelerometer Breakout Board - ADXL322 +/-2g SKU#: SEN-00849 Price: $29.95 From SparkFun. Also links to other info.

• Buffered ±2g Accelerometer Product ID: DE-ACCM2G Price: $22.95 Also other links.

• PIC Links Then search for Accelerometer.

Gas sensor

• MiCS 4514 CO and NOx sensor

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Knock Sensor

• Knock Sensor

Magnetic Field Sensor

• Hall effect sensor

Photo Diode/Transistor

• Hack a MiniPOV3 for IR capture
• Making an Amplified Color Sensor from an LED and an Op Amp

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Rotary Encoder

A rotary encoder is a device that measure ( or encodes ) rotational motion. The old fashioned mice with a ball used dual rotery encoders one to measure motion in the x direction one to measure motion in the y direction. This may be done using switching technology or by using optical methods ( so some encoders may be considered optical electronics ). Even stepper motors may be used as rotary encoders. It normally requires a microcontroller ( or speciality chip ) to decode the signals. In addition to mice rotary encoders are used for the user control on volume controls ( finally coupled to say digital potentiaometrs ), measure the position of joints in robots, or measuring the speed and/or positon of motors ( as in some servo motors ).

• Reading Rotary Encoders
• An Electronic Counter Project for Digital and Analog Signals, including Quadrature Encoders

Linear Encoder

Like rotary encoders but for linear motion. Modern digital calipers are based on this technology ( i think ). Positioning of print heads in computers may also uses this to position the print head.

Temperature Sensor

Some are analog some are digital. All can microcontroller interfaces either digital or analog. Two analog devices are LM34 and LM35. Dallas semiconductor makes a line of sensors based on their one wire networking, cool.

Further Reading

• WSN:Sensors
• Interfacing with Hardware See the section on "Input" Writtern for the arduino but usefull just for the info on sensors.
• Welcome to the ITP Sensor Workshop Wiki. A whole wiki on sensors, looks good.