Hi,
This is probably not the correct thread for your question but since it is already here....
I just learnt all these thing last year and wouldnt have gotten far without the help of the people on this forum so I thought I would tell you. If anyone in the forum knows this is incorrect or needs to be added to please do so. I am guessing as you read the post by KSouza and are posting further questions that you need the steps involved. Both KSouza and Kevin F are right use a relay it is much easier than using a transistor or darlington circuit. It does depend on what you mean connect a wire together however these wires are connected to somthing and this will determine what relay you use or whether it is suitable to use a relay at all.
To interrface the arduino to a relay:
connect your wire through the relay.
Connect the input of the relay to a digital output pin.
Set the the digital pin as an output in LIFA
To either disconnect or connect the wire set the output of this pin to high or low
Things to check:
If the ground of the circuit you are making is not grounded to the arduino you will get nothing.
The arduino digital pin puts out 25mA so you need to make sure your relay can be driven by this current, obviously also check it is the right voltage and amps for whatever your wires are connected to.
Relays can induce EMF so you may need a protection diode across the coils of the relay to protect the arduino.
If you are using it for logic you may find that a relay might not be the best option because of switch bounce causing it to disconnect and reconnect for a short period of time creating adding problems. In this instance a darlington circuit which is just multiple transistors connected together would be a better option.
