dcpower supplywiring
Consider the following power supply interface.
I'd like to power a number [1,N] of bitcoin miners, 12V, 5A each one.
question is:
You don't say what the Molex connector is coming from, but I'm assuming it's an ATX supply of some sort.
Anyway, connect the red wire to the +12V yellow, and the black wire to either of the 2 black ground wires.
The rain collector appears to have only a reed switch contact closure output. The collector itself will not produce voltages on the wires. Instead you have to connect the reed switch contact wires into a circuit that puts a bias on the wires that can be detected by the Arduino.
Since the wires are most likely running from outdoors (wet rain location) to indoors (dry Arduino location) it is a good idea to prepare some additional protection circuitry before the input to the Arduino so that if the wires experience some electrical disturbance it does not knock out your MCU board. You could try the following circuit as a starting place to hook up the rain collector reed switch.
Best Answer
Yes, you should connect red wires to +V in all cases and black wires to GND (or COM in this case, short for COMMON). Inside the power supply, the three COM terminals are connected together, and the three +V terminals are connected together.
Connect the Earth terminal to your mains earth (green/yellow or green wire).
Be sure that your power supply is rated for 12V and at least N times 5A output. Better to have more output current capacity, so that it's not running at full load all the time. Make sure your wires make good contact with the terminals, and the wires are thick enough to carry the current.