Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple Circuit

  1. Sep 14, 2006 #1
    http://img153.imageshack.us/img153/9007/untitledvb8.png [Broken]

    That is my TTL circuit. I forgot to add +5v and a circle at the top of the diagram, so pretend it's there.

    Do I have to use the voltage divider equation to get the value of Vout?

    (5v)(Rl)/ (Rl + Rc) where Rl = 1kohm, Rc = 100kohm?
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Sep 17, 2006 #2


    User Avatar

    Staff: Mentor

    Not exactly. You need to assume some Beta for the transistor, then write the equations for the base and collector currents, assuming some number for the Vbe drop. Remember that the emitter current is Ic + Ib (it's easy to forget that small adjustment and assume that Ie = Ic).

    BTW, this is not a TTL circuit. It is an emitter-follower circuit as you have drawn it. The emitter voltage follows the base voltage, minus the Vbe drop.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook