Sensor to detect nearby hand wave...

[Promocom]

In our project we use a (narrow angle) PIR motion detector to detect a hand waving within 12" or so. But i think maybe the motion detector is overkill for that purpose. I've looked at some proximity sensors but most all had very short distances usually in the mm range. If anyone knows a better way thats also reliable i'd like to know.
Thanks

 

[dougy83]

There are plenty of other sensors that could be used, but PIR is very cheap and you've stated that it's effective.

For the record, you could have a look at ultrasonic rangers, Infrared rangers, IR reflectance (using modulated source and tuned receiver)...

 

[Mr RB]

Sharp GP2 range of IR proximity sensors. Designed exactly for that purpose; to detect hands in front of hand dryers in rest-rooms.

 

[unclejed613]

there's a panasonic blu-ray player that has a capacitive sensor that works up to 3 or 4 inches away, or maybe even more. it appears to connect to the player main board through a USB or SPI port. i've never tried to see what the detection range on it is, as i always check the player's menu to make sure the feature is turned off. when they first came out our shop started getting them in for repair with the complaint "disk drawer opens and closes at random" because somebody had the feature enabled, and stacked another piece of equipment on top of the unit, or had something else near the top of the unit that would set off the sensor.

 

[nsaspook]

PIR senors are the best choice for long range detection but a PIC with the CTMU module setup as a capacitive sensor can also be used for short range (several inches) detection. I built a color organ for a open house event at work that modulates a 4 led light bar as your hand passes over a sensor. It used a sensor plate, a ground plane and a active ground plane connected to a active ground circuit (unity gain buffer amp, burr brown 3554am) to increase sensitivity. (the upside down chip here)


Some short video clips of the setup and testing:
http://www.flickr.com//photos/nsaspook/sets/72157628477730187/show/
Source code:
http://github.com/nsaspook/RGBLED.git

Active ground info:
https://www.electro-tech-online.com...lding20for20grounded20capacitive20sensors.pdf
Burr Brown chip (from the junk box):
http://www.datasheetcatalog.org/datasheet/BurrBrown/mXyzywq.pdf

 

[WTP Pepper]

SiLabs do a range of such devices.