Photoresistor/Light Sensor
This little sensor detects light intensity. More light allows more current to flow. Use this sensor to turn something on/off when it is day/night, follow a light source, etc.
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Reed Switch
This is a non-contact magnetic switch. Put a magnet near it and the switch closes, and current flows. Take the magnet away, and the switch opens. Perfect for detecting doors opening, etc.
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Is it hot in here? This digital temperature sensor will tell you, with 9 to 12 bit resolution! Uses only 1 wire to the microcontroller for communication. Simple to use and highly accurate. See our tutorial section for instructions and Arduino software.
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Make your own Arduino motion sensor / detector. Maybe you want something to happen when you walk into a room, like make the lights turn on, or have your theme song play whenever you enter. See our tutorial for using this sensor.
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It looks like a match stick, but it tells you the temperature. Hook this to a resistor and connect to an Arduino analog input pin. The voltage will vary with temperature. See the Tutorial section for our Arduino Thermistor Tutorial!
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