How do you tell when you're out of invisible ink?
Steven Wright (December 6 1955-)
PhototransistorIn 1950, the invention of the phototransistor was announced. This was a transistor operated by light rather than electric current, invented by Dr. John Northrup Shive of the Bell Telephone Laboratories at Murray Hill, N.J. It used a tiny chip of germanium, a semiconductor material, but only a single collector wire. The tip of this wire rests in a small dimple ground into one side of the germanium disk. At this point the germanium disk is only three thousandths of an inch thick. Light focussed on the opposite, un-dimpled side of the disk can control the flow of current in the wire, thus making a control device similar in function to a photo-electric cell. |
