How to switch a 12v line through a FET

[Rexlan]

I need to control the +12v supply line to a flasher unit. I prefer to not use a relay and would like to use a FET if that is possible.

I would like to make an intervalometer using a 556 chip that is started by a manual switch that will go to ground when activated. Then when it times out I want to cut the +12v line to the flasher unit.

I don't know what or how to wire the FET. I have some N channel ones here with very high current ratings. The load is about 3.5 amps @ 12vdc.

Thanks

 

[MikeMl]

If you need to switch the high-side of your load, use a PFET. If you can switch the low-side of your load, then use your NFET.

 

[Rexlan]

If you need to switch the high-side of your load, use a PFET. If you can switch the low-side of your load, then use your NFET.

OK ... not sure how it goes. I will control the gate with the 556. Who gets the +12v and who gets the load?
Any recommendation on a part number? I will probably run the 556 from an 8v regulator.

Thanks Mike BTW the camera audio thing works great!

 

[MikeMl]

Switching the high-side of a 12V 3A load with a ground-referenced low-level signal requires an interface buffer. Look at the attached.

Switching the low-side can be done with a "logic-level" NFET.