Hi,

I am thinking of building a pure hardware power on-off circuit using power mosfet. I found a circuit (see below) from the web and tried it with little change (using NDT456P rather than IRF9540 and 2N7002 rather than 2N7000) but it does not work somehow. I wonder if anyone has better idea.

Thanks.

Regards,
Eric

 

Since R5 is *'d, what's the resistance? And, do you have the URL for the site where you got the schematic?

Ken

 

Best advice I can give is to simulate the result with a spice simulator... Try free SwitcherCAD III from Linear Tech.

 

The symbol for the N-channel Mosfet is wrong on the schematic.