For non-contact switching in products with tight design space, such as disk drives, mouse and trackballs, and card detectors, the QVE00033 infrared transmissive switch from Fairchild Semiconductor may solve the problem. As a non-contact switch, it is more reliable and easier to place than a contact switch, at a comparable price.
The 7.50x4.05 mm, 5.40-mm high surface-mount device has an infrared, 940 nm GaAs source facing a silicon phototransistor across a 2-mm gap, with a 0.4 mm aperture; it also includes a daylight filter to reduce sens itivity to ambient light. Collector current is specified at 100 microamps minimum and 600 microamp maximum, while collector- to - emitter saturation voltage is 0.4V maximum. The device is priced at US$0.65 in 1000-piece lots.
For non-contact switching in products with tight design space, such as disk drives, mouse and trackballs, and card detectors, the QVE00033 infrared transmissive switch from Fairchild Semiconductor may solve the problem. As a non-contact switch, it is more reliable and easier to place than a contact switch, at a comparable price. 
