external bypass to mosfet control

[fred_b]

I have a picaxe switching a load with a mosfet (1st schematic) it works fine.

I need to add an external way to switch the load on, that is independent of the picaxe control. I am thinking of adding a diode and a switch as shown in the second schematic.

Is this a good method or does anyone have any other ideas?

Thanks

 

[Jaguarjoe]

Move your 10k resistor to the cathode side of the diode to keep the gate from floating. Be sure the picaxe can still turn on the mosfet because you will lose about 0.7V of drive because of the diode.

 

[BeanieBots]

Or simply put your switch across the FET (source to drain).
Does of course assume the switch can take the load.

 

[Dippy]

Quite right
But if using nancy-boy switch..
Assuming your PICAXE is using the same V supply as the switch why use a diode?
A couple of res will be fine.

 

[fred_b]

Or simply put your switch across the FET (source to drain).
Does of course assume the switch can take the load.

Of course. Now why didn't I think of that first? Keep it simple.

Thank you.

By the way, the load is not shown in the schematic but it is small- a camera that draws about 150mA max so yes bypassing the whole mosfet with a switch is the way to go.