Inexpensive sensors

by electronichamsters

Some cheap sensors for your wireless Arduino node.  Look for them on e*bay for the cheap price.

Parts List

$2, Ultrasonic distance sensor.
Good for measuring distance of things, with resolutions down to an inch, and a range of between 3 inch to 6 feet (although I’m unsure about the upper range).  May suffer from odd readings because of echo.  I’m using this for the garage door monitoring Arduino.

$2, DHT22 Digital Temperature and Humidity sensor

$2, PIR (Infrared) Motion Sensor
I use these as touchless buttons to turn on lights.  Also useful as part of a DIY security alarm.  These have two pots to adjust sensitivity and duration of the output pin.  Watch for variations – some can work at 3.3V, some have to have 5V or more.  You may be able to cut the voltage regulator and power it directly from a 3.3V system.  Remember the pull-up resistor.

 $1,  Photoresistor
I use it in the garage to see if the light got left on.

$6,  Smoke & combustible gas sensor MQ-2
Email yourself when your house is on fire.