I want to connect 24 servos to Arduino. I will use an external power supply. When using an external power supply (to the best of my knowledge) you only connect the signal and the ground to the Arduino.
For 80Amps however I was told to only connect the signal to the board from the servos
(servo pos and neg to battery).
What do you think?
80Amps is the maximum the servos could ever draw if needed.
Is it enough to have just signal connected to the board?
Thanks in advance!
do u have a schematic?? that would help.. only 'signals' are output from all arduinos..u might light up an LED but thats about all..
I haven't purchased an Arduino yet, so I'm asking before hand if it's possible. The question is pretty straight forward...how to power many servos with a high load requirment
The board can only sink or source milliamps directly from the pins at Vcc (5 or 3.3 volts). You need some kind of amp between Arduino and the servos. Those amps would be controlled by the "signals."
What is your design?
kolleamm:
I haven't purchased an Arduino yet, so I'm asking before hand if it's possible. The question is pretty straight forward...how to power many servos with a high load requirment
You could power a batleship wit an arduino withe
kolleamm:
I haven't purchased an Arduino yet, so I'm asking before hand if it's possible. The question is pretty straight forward...how to power many servos with a high load requirment
The arduino is only the control signal.
With the right driver boards you could drive a battleship.
What are you trying to do ?
I'm trying to control the body of a large robot. Each motor can draw around 5 amps at 7.4 V.
I realize the amps would be too high for the board to handle, so how would you wire this in the most basic sense?
Each servo has 3 cables, signal, positive, and negative. All I'm asking is where do you put them if the current is so high.
Positive and negative go to the relevant terminals on your 80A supply. The signal goes to the Arduino.
You also have to connect the grounds - the Arduino needs to have one of its ground pins connected to the negative of the supply.
Thank you very much for your response Morgan.
My only question is if I connect ground and signal to Arduino like you said, will the high current pass through the board or just the motors?
The trick is to take the grounds for the motors and run them back to the battery negative. You also run the ground from the Arduino back to the battery - the common meeting point for the grounds should be at the battery (or a big junction point). That way only the control signals from the arduino go out to the motor controllers (it can't drive the motors direct). The reason you only tie the grounds together back at the battery is because all wire has some resistance and the more current you pull through that wire, the bigger the voltage drop across that wire - you want the Arduino ground to be referenced to the battery ground, not some other point that is floating depending on how much current is flowing.
Connecting grounds can actually help keep unwanted current from flowing to/from the arduino due to a possible ground potential difference. It also allows logic signals to work properly. It provides a zero potential reference for anything connected to that ground.
The servos will draw current from the 80 amp supply and return to ground.. the arduino is not in the path of this high current.
What gpsmikey said is important advice. One common point for all grounds so you don't have voltage drops from the wires themselves.
Going to be one crazy robot! Take videos when you are done.
Thank you all very much. I'm glad I got this question out of the way. You guys will definitely be the first to see it 
Thanks a million
You need to connect the grounds together - if you don't the "signals" will not work.
You can power [edit - language] all from the ATmel chip! Digital electronics do not work by providing "power". You can control something which requires vast amounts of power via an Arduino or any other micro controller it you wish, but you must use the correct extra circuitry.
Mark