Transistor as switch, power saving from switching current source?

Discussion in 'General Electronics Chat' started by Thecomedian, Mar 7, 2015.

  1. Thecomedian

    Thread Starter New Member

    Oct 12, 2013
    22
    3
    https://learn.sparkfun.com/tutorials/transistors/applications-i-switches

    Are there any complications from making the resistance as high as possible to limit power consumption from the control source? I can make an identical circuit and put 50k into R(b), receiving a negligible current loss for the LED/I(CE), and greatly improving the power consumption for the switching control source.

    Is the gain of the transistor a factor in using a transistor as a switch?
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,977
    3,221
    Yes, the transistor gain is a factor. Good engineering practice is to use a base current no lower than 1/10th of the collector current to fully turn on a BJT transistor.
    If you want a lower control current than that, you could use a MOSFET which requires zero gate current to turn on.
     
    Thecomedian likes this.
  3. Thecomedian

    Thread Starter New Member

    Oct 12, 2013
    22
    3
    Thanks again, man. I wasn't sure. Going into my notes ;)
     
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