1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Simple DC Circuit

  1. Jun 3, 2007 #1
    1. The problem statement, all variables and given/known data
    Design a DC cct having a 15V battery to provide the following node voltages: +10V, +5V, and -5V with respect to a circuit ground node. Select your resistors such that the max power demand on the battery does not exceed 1mA.

    3. The attempt at a solution

    I made a cct with 4 series resistors. 15V source is in series with R1, which is in series with R2, which is in series with R3, which is in series with R4. Since in the question the voltage drops are all equal (5V), I selected 4 equal resistors of 4k. With this design I can node voltages of +7.5, +3.75 and -3.75 with respect to a circuit ground. (I chose the cct ground to be the node connecting R3 and R4)

    For the life of me, I dont see a way to get the node voltages specified in the question. Can somebody PLEASE guide me in the right direction??
  2. jcsd
  3. Jun 4, 2007 #2
    Try sketching down the outputs you want in order, starting with -5V, 0V (ground), 5V and 10V. How many gaps are there between the nodes?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook