You might think this is not a sensor but just a button but it is the most important sensors to the computer. We input our characters via a keyboard, a collection of buttons! A few tricks can be performed by the button sensor to have different behaviors.
|Big button sensors, push button and numeric pad|
- pushing a button to turn a LED on or off ( AKA on/off pushbutton switch )
- holding a button will turn on the LED, releasing the button will turn off the LED
- holding a button to adjust the brightness of the LED or two button volume control on laptops
- double click the button to select a menu or just to the next sound track, this is commonly found on the mouse buttons or mp3 players to skip a track a song.
- triple click on the button, this can be found on Apple iPhone headset/mic to play the previous sound track.
- buttons arranged in four directions to navigate up/down/left/right
This is probably the second most common sensors that are found anywhere from volume controls to old generation of iPad. Apple designers found out that it is much easier (and faster) to select songs using a rotary sensors that an bunch of arrow keys. All our mouse have a wheel in the middle made for scrolling functions. An earlier version of rotary sensors was found in the side of older Sony products called the jogdial, a single hand operation to combine the push button with a rotary sensors.
The above is the rotary sensors for Arduino to be used as input interface for your projects.
|Sharp IR range sensor|
Motion Detectors (PIR)
These sensors are commonly used in burglar alarms, automatic lightning and those annoying sensors in 7/11 that plays a tune when someone walks into the store. They are use to detect presence of a person within a range. They are called Passive IR or just IR motion sensors. The white dome is a lenses that focus the energy to a pyroelectric sensors that detect changes in IR radiation. Ladyada.net have a detail article about the PIR motion sensors.
|Laser and light dependent resistors (LDR)|
A cheap and easy way to make one of these sensor is using a laser pointer and a light dependent resistors or photocell. Once the laser is cut, the photocell will detect the change in light and trigger an alarm. This is both fun and easy to make.