turn on load with computer signal via USB

Discussion in 'General Electronics Chat' started by vahidasadi, Oct 17, 2012.

  1. vahidasadi

    Thread Starter New Member

    May 21, 2010
    11
    0
    hi everyone
    i'm working on a project witch it's goal is to turn on a load (it doesn't matter) using usb, i have programmed my micro and the software part , the turn on order receives via usb port to controller and then it send the negative voltage to the transistor, i decided to use BS250 (DMOS up to 250 mA drain current) and pulled it's gate up with 10K resistor and after receiving the signal from micro it turns on and +5V voltage goes to LM317 to be regulated ,now when i connect my load( it takes about 45mA) to circuit it can't turn it on but when i connect +5V after transistor there is not problem, i thought that maybe BS250 can't tolerate the current consumption so i replaced it with B564(BJT up to 1 A) transistor but no change
    now i stuck and don't know what to do, is there a problem is design or i should check other options?
    i have attached the circuit schematic
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,634
    2,342
    Hello,

    What do you have to interface the USB to the switching signal?
    Can you give us more details.

    Bertus
     
  3. vahidasadi

    Thread Starter New Member

    May 21, 2010
    11
    0
    It's a simple camera board bought from local store i don't have any problem without load and after lunching software part in computer the little LED turns on i even used computer power's +5V but no difference with USB
     
    Last edited: Oct 18, 2012
  4. vahidasadi

    Thread Starter New Member

    May 21, 2010
    11
    0
    The problem resolved,i had used the capacitors in wrong direction
     
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