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...
"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...
You can loose the diode once you know the polarity for button connections. The "+" terminal connects to the collector, "-" terminal to emitter. Can determine polarity with multimeter (or trial and error).