Transistor Voltage Divider

Discussion in 'General Electronics Chat' started by jmsparkland1, Apr 2, 2012.

  1. jmsparkland1

    Thread Starter New Member

    Feb 29, 2012
    In Volume 3, in the chapter on bipolar transistors, the author writes about how to practically forward bias the transistor. He does this by creating a voltage divider with two transistors. How did the he figure out what two values of resistors to use? Obviously I understand Ohm's law, but how could he decipher which values would be appropriate? Any help would be appreciated.
  2. jmsparkland1

    Thread Starter New Member

    Feb 29, 2012
    Sorry, here's the picture
  3. Potato Pudding

    Well-Known Member

    Jun 11, 2010
    Looking at those values?

    I suspect he just used a 10k potentiometer and turned the wiper until he had the bias right, and then measured the resistance on each side of the wiper.

    Some times there is no math needed.

    By the way - that is not the best way to drive a speaker.
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
    I hope you understand that most of the circuits in that section are not recommended for actual use. They are just there to illustrate the principles of BJT biasing, and are not practical.
  5. Audioguru


    Dec 20, 2007
    That is the stupedist audio power amplifier circuit that I have ever seen.

    If anybody wants to burn out the speaker with 0.94A DC current in it all the time, then the transistor will also burn out since it dissipates 7W.
    The transistor must have an impossible high current gain because the resistor values are much too high.