Hi,
I have to use solenoids with Arduino. I've checked the Solenoid Tutorial on Arduino Playground, but honestly I'm really new to electronics etc and there's a lot of things I don't understand about the schematics...
Are the IRF640 transistor and the zener diode D2 a unique component, or do I have to link them together?
What is JP2? And TP1 and TP2?
I tried to understand something more from the pictures, but they're really messy and don't help at all...
The solenoid ground can and should be connected to the Arduino ground. Powering the solenoid depends on its particular requirements. If it's a big beefy thing then you will probably need external power but the Arduino +5 volt line may be ok for a small solenoid.
btw, the picture in your link is more or less the same as the one reply#3.
The TIP 120 will be more than adequate. But you will need to use an external power supply, 6 volts DC at least 1 amp (although a 5 volt 1 amp supply should work in a pinch)
It depends on the solenoid. Yours wants 6 volts at a little over an amp.
There are lots of devices that use a 5 or 5.5 volt 1.5 amp wall warts that you may be able to scrounge. I seem to have a box full of them from old IP routers and switches that were junked