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  1. #1
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    360 degree servos in analogue gauges

    Hello.

    Would it be possible to use a 360 degree servo in an analogue gauge as an air speed instrument?

    Normally you would use a normal servo with a 1:2 gear, but with the new 360 degree servos readilly available, this would appear a good idea.

    However these servos appear to be continuous rotation, so maybe a stop would need to be in place?

    Any thoughts on this?

    Thank you.
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  2. #2
    500+ This must be a daytime job



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    Re: 360 degree servos in analogue gauges

    Alex,

    Not sure the 360 servos sense a relative position, they just turn cw or ccw don't they? I think this is why stepper motors may be a better choice because they keep track of the position. Could be wrong, but that is my understanding.

    Reid
    http://juneaucessnasim.blogspot.com
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    Re: 360 degree servos in analogue gauges

    Hi,

    To be honest I did read a little more on this and your right.

    I need to build an RPM gauge for the right of my pit and was wondering if I can 'pull a fast one and cheat'

    Cheers,

    Alex
    Building An Airbus In My Garage!

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    500+ This must be a daytime job Ronson2k9's Avatar
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    Re: 360 degree servos in analogue gauges

    Either way you will need a controller for the gauge. I would suggest you take a look at Mike Powells site on building gauges. You can also check out FSCockpit.com article on mechanical gauges. If you are good with electronics you can build the items yourself or you can go to Phidgets and get them ready built.

    Both will require a controller (a sensing unit) to detect where the needle is. A pot is the best choice however a pot only turns so far about 300 degrees so you have to gear the receptor so that the amount of turns can be read by the pot.
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  5. #5
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    Re: 360 degree servos in analogue gauges

    Was thinking of an opencockpits servo card, they are only 25!

    Luckily, the RPM only turns under 270 degrees, so was thinking that there is an easy way to implement this.

    I have a spare simkits housing and faceplate, just need a servo and if required some gears to get the movement required.

    Alex
    Building An Airbus In My Garage!

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    Re: 360 degree servos in analogue gauges

    Alex

    It is not difficult to make a gauge for use with an OC servo card. See here

    http://www.737ng.co.uk/djb/brake_pressure_gauge.pdf

    Regards

    David

  7. #7
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    Re: 360 degree servos in analogue gauges

    Hi,

    Yes I will be making a gauge using gears:

    I am thinking that this gear set will be good (cheap and cheerful):

    http://www.ebay.co.uk/itm/DIY-Gearbo...#ht_1044wt_825

    Cheers,

    Alex
    Building An Airbus In My Garage!

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    Re: 360 degree servos in analogue gauges

    Gears and servo now ordered, Ive made a start atleast!



    Thanks to David for the idea VERY simple idea using a mini servo and gears!

    This gauge will be for the co pilot side of my Cessna where only 2 gauges are needed which is the tachometer and ASI.

    If I can pull this off then I will have the confidence to make more!
    Last edited by AlexJ; 10-03-2011 at 02:14 PM.
    Building An Airbus In My Garage!

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    Re: 360 degree servos in analogue gauges

    Alex

    One further bit of advice. Choose a gear combination that gives a little bit more movement than you need. The Hitec servo/OC Card combination does not work well at the servo limits of travel - it can get a tad erratic!

    Regards

    David

  10. Thanks AlexJ thanked for this post
  11. #10
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    Re: 360 degree servos in analogue gauges

    Advice taken! When I get my gears through the post I will make a temp breadboard and experiment until I get the correct/desired rotation. The Cessna tacho requires just under 270 degrees of movement. However the RPM of a Cessna 172 never exceeds more than 2500-2700 which equals around 180-200 degree of movement. So I still have plenty of movement to play around with.

    Thank you

    Alex
    Building An Airbus In My Garage!

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