How heat affects a transistor ?

Discussion in 'General Electronics Chat' started by Tree1, Mar 8, 2012.

  1. Tree1

    Thread Starter Member

    Nov 30, 2010
    46
    0
    Can the pulse width of an output signal of transistor change if the transistor is placed in a very hot environment ? If possible, please explain.
     
  2. electronis whiz

    Well-Known Member

    Jul 29, 2010
    519
    27
    check out this link. http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/transtemp.html
    i just glanced at this it is a bit hard to understand at least for me. if i understand corectly though the heat causes an increase in current in the trigering probably base lead thus reslts in an increse in current flowing from the emiter to colector. i t would seem to me if my understanding is corect and this article is corect you could see some fales pulse outputs caused by a slight volatage occouring because of the temperate. normaly transistors depending on the load are heat sinked to prevent isues and from cooking them selves. also when soldering you should heat sink them with a small pliers or transistor clip. hope this helps. also chack this link for further info https://www.google.com/#hl=en&outpu....,cf.osb&fp=fb2e33546f0a907c&biw=1280&bih=855. i have never delt with this before so hopfully sombody that has can help also.
     
  3. srinivas@adroit

    New Member

    Feb 4, 2012
    8
    0
    Transistor made by semiconductor, so silicon is positive co-efficient temperature depended one. So temperature affect the transistor operation.

    Thank you !!!
     
  4. srinivas@adroit

    New Member

    Feb 4, 2012
    8
    0

    Transistor made by semiconductor, so silicon is positive co-efficient temperature depended one. So temperature affect the transistor operation.

    Thank you !!! :)
     
  5. Tree1

    Thread Starter Member

    Nov 30, 2010
    46
    0
    Thank you guys for your information.
     
  6. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Have you studied thermal runaway yet? The basic two resistor BJT circuit is very vulnerable to this. Heat causes the transistor to turn on a little, which can cause more current, which heats the transistor even more, and so on.

    The reason the classic 4 resistor transistor circuit exists is to clamp down on this. It is not the only electronic circuit that has this problem, poorly designed LED circuits can do it to, though with just a little care it isn't a problem.
     
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