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 use microcontroller interfaces LM34, LM35

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.