I'm looking to turn a power supply on or off based on a logic signal from the Arduino. I've looked into some MOSFET's, but from what I've found I'd need 2 MOSFETS and an Op-Amp to be able to have it do what I need - albeit without being very elegant.
I've also looked into 12v switching regulators, but I'm having trouble understanding all the components I'd need to get this to work.
And finally, I've looked into 12v step-up regulators, but I doubt that I'd be able to draw 250mA out of that using just the Arduino output alone.
I'd really appreciate any advice in this area, as I'm a bit new to this.
You probably won't get a helpful answer unless you tell us what type of component (motor, lamp, sensor, etc.) is to be powered on and off, and how much current it requires.
You still haven't told us what sort of load you will be switching, although in the original post you imply that the current draw is 250mA. If it's a steady 250mA, then a PNP transistor configured as a high-side switch, driven by an NPN transistor, is the simplest solution. However, depending on the load, the surge current at switch-on could be many times greater, in which case it would be better to use a mosfet and perhaps a current-limiting circuit. So you need to tell us more about the load being switched.
With such a small load, you'd get away with something like a Tip31 power transistor (and place a diode in for any inductive kickback ) and a 1k resistor to base.
cjdelphi:
With such a small load, you'd get away with something like a Tip31 power transistor (and place a diode in for any inductive kickback ) and a 1k resistor to base.
He's already said that he wants to switch the positive supply to the load, not the negative supply, so this solution is not applicable.
cjdelphi:
Although prices are coming down fast for fets check out this..
