| http://www.w3.org/ns/prov#value | - The light switch 76 is of conventional construction, including a light source such as an infrared light emitting diode (LED) and a light detector such as a phototransistor (e.g., industry standard part number OPB804 such as is available from Optek and several other manufacturers) disposed at a spaced-apart distance from each other.
|
