Saturday 30 March 2013

Invention of the phototransistor was announce

The invention of the phototransistor was announced on March 30,1950 ( Murray Hill NJ). 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.