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

 

Hello,

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

Bertus

 

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

 

The problem resolved,i had used the capacitors in wrong direction