We're designing a project that uses 30 servo's.
I've got some questions about the power supply for these to work.
It's not a 'mobile' project so we can use a wall wart or something similar.
I've got little knowledge of these kind of things so I don't know what I'm looking for.
Does it needs an AC to DC adaptor or something else?
It needs to be at 6V I suppose but what about the ampere(is this the correct term in English?) (A), is it just the summation of the A's needed by the servos?
How do I wire everything up? Do I need to separate the arduinoboard power supply and the servos power supply or can I use a single power supply to power and the arduino board and the servos all together?
I'm living in Belgium, we've got 220V/16A standard.
I can't yet read out the amount of amps needed by a servo at the moment because I haven't decided which ones to use. Can't I just get this information out of the technical data sheets provided on the manufacturer's website?
A lot depends on if the servos are going to be operated simultaneously or not, how much mechanical load is on the servos and of course the specific servos being used. I usually plan on 1 amp of current for each servo, worst case, but again that can vary per application. Hobby servos usually work from 4.5 to 6 vdc and 5vdc is the most common voltage to use. So you see you are going to need a pretty large regulated +5vdc power supply.
Probably the most cost effective power supply you could use is a PC power supply as they can have lots of +5vdc current available in most models. You may have to modify the supply some for manual turn on and off and have minimum load resistors installed. There are many Internet projects showing how to utilize PC power supplies as general purpose DC supplies.
Yes the servos will be operated simultaneously, the load on the servos won't be extremely high (gears will be attached to them to create a linear motion like this: http://www.geardesign.co.uk/images/gears/rack-and-pinion-gears.gif , the straight section will be attached to a piece of fabric). So basically it's a sheet of fabric (about 60cm by 30cm) that's divided into a 5x6 grid. Each gridpoint is connected (through the gearsystem) to the servo.
I've got some old PC power supplies lying around, maybe I can modify them to my needs, can you push me in the right direction to find a tutorial or something on how to do this. I really have no experience with this kind of electrical stuff.
How do I hook up the modified ATX to my arduino board? Or do I need to hook it up only to the servos? I'm afraid of damaging the arduino board by putting to much amps (about 30) on it..
How do I hook up the modified ATX to my arduino board? Or do I need to hook it up only to the servos? I'm afraid of damaging the arduino board by putting to much amps (about 30) on it..
The +5vdc from the power supply would only run to all the +5vdc connections on the servos, usually the red wire. The ground wire from the power supply would run to all the servos, usually the black wire. You will have to decide if you are going to run the +5vdc and ground wire as a 'daisy chain' buss (must use fat wires) or seperate ground and +5vdc wires to each servo (you then can use normal servo size wire). Then you need a single wire to run from the supply ground to a Arduino ground pin. Not sure how you can get one Arduino to drive 30 servos independtly, mega has enough output pins but I have no idea if the servo software library can handle 30 servos. You should probably see if the software can handle 30 servos before making the hardware investment.
Well, we are using two arduino's actually, controlled by firefly (http://www.fireflyexperiments.com/), one mega and one uno. The software supports 24 servos on the megaboard and 6 on the unoboard.
This should work, the only 'problem' I had left was how to power the servos, which thanks to you is hopefully going to be resolved when I mod my pc's power supply ;).
I suppose it's not a problem to use the power supply for both arduino boards (meaning to run two wires from the supply ground to the two board's ground pins?
I suppose it's not a problem to use the power supply for both arduino boards (meaning to run two wires from the supply ground to the two board's ground pins?
Thanks to retrolefty's link, the power supply is working ^^
The servos will be arriving this week and in preparation of hooking them up to the boards, I've got some final concerns/questions.
The powersupply turns out 47 A, I'll only need about 30A, can this in any way harm my arduino board?. I'm going to use normal size servo wires to connect all the 30 servo's to the +5vdc 'port' of the powersupply. Is this possible (with all those 47 amps running through them?) When they are not moving there will be a 47A current running through the wires, is this harmful for the servos or the board?
I need a usb connection to communicate the values to my computer(and 3D software), is this a problem? (Because I'm using the power supply's ground to the ground pin of the board).
Are there any easy solution to hook up 30 servo wires to one wire that runs to the power supply's +5vdc & ground outlets? (preferably a link to a picture or something so I can show it to my local electronics shop keeper?)
The powersupply turns out 47 A, I'll only need about 30A, can this in any way harm my arduino board?.
Current is pulled, not pushed. So, the ability of the power supply to supply 47A does not mean that it will push 47A through the Arduino. The Arduino will pull what it needs, like the servos will, if the power supply can supply it (which it seems yours can).
I need a usb connection to communicate the values to my computer(and 3D software), is this a problem?
Only if you don't have one. Having a USB power connection and external power available is not a problem. The USB power will be used, as long as it is available.
Are there any easy solution to hook up 30 servo wires to one wire that runs to the power supply's +5vdc & ground outlets?
This is a guaranteed way to short out the power supply.
Now, if you meant two wires, one to +V and the other to ground, then any way of connecting all the +V lines and all the ground lines together will work.
The powersupply turns out 47 A, I'll only need about 30A, can this in any way harm my arduino board?.
Nope.
Is this possible (with all those 47 amps running through them?)
There won't be 47A running through each wire, just whatever each servo uses, 1A or thereabouts.
When they are not moving there will be a 47A current running through the wires, is this harmful for the servos or the board?
When they aren't moving they'll use even less power.
The 47A is what the power supply can make available if required, but the circuit connected to the power supply has to take that power. Yours will take a lot less.
You will not damage anything.
need a usb connection to communicate the values to my computer(and 3D software), is this a problem? (Because I'm using the power supply's ground to the ground pin of the board).
That's not a problem.
Are there any easy solution to hook up 30 servo wires to one wire that runs to the power supply's +5vdc & ground outlets?
It's not hard, but harder in some ways than running the 30 wires. It's more a mechanical thing than electronic because you need a large wire to carry the 30A (depends on how long the wire has to be) but this large wire has to be connected to the small servo wires.
So how long would this single wire be? Remembering that the current has to come back as well, so the total lenght is needed.
Remembering that the current has to come back as well,
Good point and maybe not obvious to some beginners. The common high current wire size if used to supply +5vdc to the servos is also required on the ground wire going to all the servos. If you are wiring all servos +5vdc and ground wires separately to the power supply then normal servo size wire will work.
