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[foh-toh-tran-zis-ter] /ˌfoʊ toʊ trænˈzɪs tər/
noun, Electronics.
a transistor that amplifies current induced by photoconductivity.
Origin of phototransistor
1945-50; photo- + transistor Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for phototransistor
  • If the prism-shaped probe tip is dry, the light is reflected back up a second shaft where it is detected by a phototransistor.
  • The rotation of the cup was converted into an electrical signal by a phototransistor and light source.
British Dictionary definitions for phototransistor


a junction transistor, whose base signal is generated by illumination of the base. The emitter current, and hence collector current, increases with the intensity of the light
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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phototransistor in Science
A transistor that regulates current or switches it on and off based on the intensity of the light it is exposed to rather than an external electric signal. Phototransistors are used in many electric-eye applications, including digital cameras, in which millions of tiny phototransistors map an image into an array of electrical signals. See also photoelectric effect.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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