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

JFET question

  1. Nov 23, 2006 #1
    I have a problem of calculating the current through a system. It is a simple JFET transistor with the source grounded. The gate is reverse biased with a 3v potential, and the drain has a 2000 ohm resistor in series then a positive 20v potential in series which is of course grounded. How would I go about finding the current through the load resistor?
  2. jcsd
  3. Nov 23, 2006 #2
    ...Assuming an n-type Si transistor

    Also I dont have any other information.. I know that the more and more you apply a negative voltage on the gate, the smaller the channel gets which leads to more resistance across the source-drain channel. The answer Im lookin for is 2mA.. that would lead to a resistance of 8000 ohms, cause we still have a 2000 ohm resistor in series therefore 10000 ohm and with a voltage across the source-drain channel of 20 volts.. you get your 2mA answer, I dont see how you can get this bridge voltage without knowing something about a family of curves or the like???
    Last edited: Nov 23, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook