clock in general: how precise is the arduino board? do I need an extra quartz? And how would
I use it?how big is the arduino mini? I've read about width and lenght (3x1 cm), but I've seen nothing
about the height of the board...LEDs: I'll need to order a number of LEDs. What will I have to look at while ordering them?
Do they need to be 5V? Or could I also order 3V LEDs? And where can I find information which
LEDs need what kind or resistor?and finally: do you know of a super easy explanation of shift registers? I've read the tutorial
on this page, but I frankly don't quite get it. I'll certainly work it out for myself, but it would
be nice if there was an easy explanation of the concept behind it, somewhere...
The Dieci has a quartz crystal on it. It should be accurate within about 5 seconds a day. That's comparable to a commercial quartz watch.
The mini is in the form factor of a standard dip package. Including pins it's maybe 7mm thick (that's my estimate).
The LED question is a lot more complicated than that because what people don't usually recognize is that they're current devices, not voltage. Basically though, if you want 20mA, the resistor should be ([supply voltage] - [led voltage]) / 0.02. Or 50*(supply voltage - led voltage).
Supper easy explaination of shift registers would be "serial in, parallel out" or "parallel in, serial out" depending on the model.