I am building simulator aircraft instruments using servos. I am using a Uno and want to power the servos via an ac to dc solution. What sort of power supply should I be investigating?
I have searched through this forum and discovered that servos can draw 1 amp at startup. I will eventually be looking at 12 (isn't this the maximum an Uno can control) servos. Does this mean I will need a 5v 12 amp supply?
I was wondering about using a hacked ATX power supply, but I don't think the 5v rail produces those kinds of currents, do they?
If I am missing something, please let me know, and any advice is appreciated.
An ATX (or earlier PC) power supply should be fine.. You may need to put a constant load on it ( a 6 volt tail light bulb works well). Most such supplies are good for 12A or more.
But: if you don't need super-instant response, and you change each servo / indicator individually and give 1/10 of a second or so for the servo to "Settle" you may not need such a large power supply. Most aircraft instruments I've seen in the cockpit don't change scale position rapidly, and if they did it might not be coherent information anyway?
This would be even better: http://goo.gl/E8cJq it's rated at 5V 2 Amps... Can you arrange to give a little settling time as you set each new servo position?
IS it true that usually changes in Servo position will be small? (Except for Artificial Horizon in a spin??).. I think you'd be fine with 5V 2A. There's no real mechanical load on these servos, right?
Also if the smaller servos would be OK for your application, they draw less current: http://goo.gl/LP7kH
You gotta show us photos of this when you are done..
Some car/boat people might want to do a similar thing..
I'm thinking of making a 2 foot size voltmeter for classroom use...
You are correct that changes will be relatively small in degrees travelled. I will definitely look at wall wart power supplies first as they are relatively inexpensive.
I will be happy to share when I get some finished product.
Right now I am relying on a program written by JimNZ(freeware available here: jimspage.co.nz extracts values from Microsoft Flight Simulator X (FSX) and sends them via serial to my Sketch. I am brand new at this so am happy to stand on the shoulders of giants!
Some of the instruments require 360+ rotation, so after the servo business is figured out, I will probably be poking around for other solutions (steppers most likely).
You probably won't need to worry about the power requirements of the servos. You are not going to be moving a large mass so the forces involved should be fairly low.
Is the rotation just 360 or is it "around and around"??
There are a few schemes for using standard servos to get 360 rotation for "look around" sensors on robots etc.
What kind of positional accuracy is needed on these?
How would you do a typical "Around and around" Altimeter with numerals in a little window? Do you need to??
Some of the instruments will require more than 180 degrees of rotation. I was planning on doing this with a gear train, but do you have a different way?
Other instruments such as the altimeter are "around and around". There is a project I have been watching(http://www.mycockpit.org/forums/showthread.php/24131-How-to-Convert-a-real-Cessna-Altimeter-for-Sim-use?highlight=altimeter+servo that hacked a servo into continuous rotation, and added a multiturn pot for servo feedback. I am trying to replicate a small piston engine plane (basically a cessna 172, but with a few cockpit options to allow my pit to control a cessna 18x as well. The big difference being the addition of a constant speed prop controller and a manifold pressure gauge) so I do not need the altimeter to run above about 15k feet.
This is a bit down the road, as I am working on the simpler stuff right now such as engine gauges and a vertical speed indicator. They will have one or two needles per gauge and should be pretty simple to set up.
