My basic concept is to power several (a dozen or so), with a single power supply. I have a 5v (60 amp max) power supply and was thinking I could use vampire taps commonly used for yard lights.
Each Arduino would have a vampire tap and get its power from that single power bus.
this seems to make sense, but I was wondering if the max amp rating of that supply was something that the arduino power regulators can handle, or do I need a way to step it down. If so, what do you recommend?
As long as the supply is regulated at 5V each Arduino will draw only the current that it needs.
I do not see anything wrong with using the "vampire taps".
I was wondering if the max amp rating of that supply was something that the arduino power regulators can handle
This is a common misconception of beginners, you are not alone. You apply the appropriate voltage and the load takes what it needs. The current rating of the supply just means it can supply anything up to that.
The supply into your house can probably supply 10000A, at least until the fuse blows, that does not cause a problem for the tiniest of electrical appliances.
I suspect you don't understand Ohms law
Also worth reading about Kirchoff's laws
These are basic to all electronics.
I agree with PerryBebbington, How are you going to manage polarity with the vampire taps, if you get it wrong you will be replacing boards etc. Your design will not work reliably, you are going to have noise and voltage problems. Go to at least 8 volts and use the Vin terminal, you will get some filtering and noise suppression at each Arduino. If you insist on using vampire taps put a bridge after the tap and before the Arduino, with a bit of bypassing and bulk capacitance, then you connect it in any polarity. However if you do this you will have to take your voltage to at least 10V so make it easy and use a 12V power supply. Just do not power accessories with the arduino 5V supply, it is very limited in what it can do. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
How long is your vampire buss?
You will likely see voltage drop over any lengthy cable.
I would initially suggest using a large 9V supply or similar, and feeding the barrel jack input, so that each ‘duino regulates its own (local) 5V supply.
That way if the cable drops to 8 or 7 V over it’s entire length, you’ll still get a clean 5V at the chips.
mike_littlerock:
I have a 5v (60 amp max) power supply.......... but I was wondering if the max amp rating of that supply was something that the arduino power regulators can handle, or do I need a way to step it down. If so, what do you recommend?
Assuming you have 5v Arduinos, 5v is what they need. You supply a kosher 5v to the 5v pin and you are off to the races. The regulators are voltage regulators, not power regulators, and are not involved anyway. To have them in the game you need 7v minimum from the power supply, which you don't have. The "60 amp" suggests the power is probably adequate, and your real problem is to ensure that 5v is indeed available at the Arduino 5v pin. God only knows what your installation really is but, if the supply cables are long, it might be time to read reply #4 again, and it might even be cheaper to ditch the 5v 60A.
Hi,
If you are going to use the 60Amp supply, make sure you place a fuse in the 5V wire.
This fuse needs to be rated about 50% higher than the total current being USED by all the Arduinos.
Say a 10Amp fuse.
That way if you have a short then the fuse will open at 10A and give some protection to your electronics.
Without the use of a fuse, the short will receive the full 50Amps of the power supply.
Possibly letting expensive smoke out of your equipment, before the supply shuts down. :o :o
That is why a car that has a battery that is capable of 1000A into a short, has so many fuses for different circuits drawing current off it.
Tom... 
going to make sure of polarity by a simple but reliable means.. one of the leads on the wire (and on vampire) is marked.. simply making sure i always follow the convention of marked = positive and i am safe. I do like some of the suggestions posted and will take that all into consideration.
thanks so much for taking time to answer!
