digital switch ? with arduino . how to do it

pretty sure I covered that in my example

"for example a led torch, the switch is not switching the power to the led only switching (triggering) an IC to turn on the torch."

= LOW POWER ...yes like a remote.

thanks

septillion:
You have to be more precise. Yes, probably it's possible but what is the best/easiest method we can't tell. The "switch" might be a tiny switch on a remote or a massive 400V 3-phase switch. Both switches, both controllable from the Arduino but the solution is quite different...