I need to interface the arduino with a stopwatch.
I need to go from a digital I/O to the start/stop switch on the stopwatch.
What parts do i need to use this?
-IT
It depends on what is at the stop watch. Is it an electrical signal? If it is I would use an opto isolator.
This is basically an LED so use it like you would any LED. At the stop watch end the transistor should go across the switch with the emitter (line with an arrow) connected to the negative side of the switch and the collector (no arrow) the positive side.
thank you, do i need anything else to use an opto-isolator
Just a resistor to limit the current in the LED just like any other LED.