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47535Re: [SeattleRobotics] Engineering problem for discussion

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  • Max Cato
    Feb 1 5:14 PM
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      Definitely do-able. With a 10k pot you can take the +5v output of the arduino, hook it to one end, and use the arduino's gnd for the other end (with your sense being the middle connection, of course). Just make sure your servo's current draw isn't bigger than what the arduino can put out. Otherwise you'll need to use FETs/BJTs to make sure you can power your servo... My guess is that the Arduino should be able to put out enough current for that, though.
      The other consideration is that servos make a bit of gear noise when moving. I realize you're playing on a pipe organ, but is that acceptable for your customers?

      From: KM6VV <KM6VV@...>
      To: SeattleRobotics@yahoogroups.com
      Sent: Friday, February 1, 2013 4:47 PM
      Subject: Re: [SeattleRobotics] Engineering problem for discussion
      Should be easy enough to do. Use a 10K pot or so. Plenty of "demo"
      programs on the web illustrating how to interface pot (analog input) and
      a standard servo motor to an Arduino UNO board. Probably want to scale
      the pot data to the range wanted on the servo.

      Alan KM6VV

      On 2/1/2013 2:34 PM, hesperion22 wrote:
      > Dear Group,
      > I am an admitted Newbie so please don't laugh. If any members could take
      > an interest in advising me it would be greatly appreciated. I am trying
      > to accomplish a certain engineering solution. It strikes me that your
      > field of expertise may be precisely the ticket. I have been quite
      > enjoying your discussions from the "outside".
      > _Background:_ We are a pipe organ restoration and building firm. As such
      > we work with a wide range of situations and utilize equipment of a wide
      > range of ages, from very old components to newer. One of the challenges
      > we often face will require some explanation so that you might understand
      > my inquiry better:
      > An organist seated at the console, on the bench before the keyboards and
      > over the pedalboard has at his/her disposal a lever-pedal near the
      > center of the panel just forward of his knees. (This pedal is roughly
      > analogous with a gas-pedal on a car. The pivot point however is in the
      > center rather than at the heel.) The pedal is used to control the
      > opening and closing of "swell-shutters" which form the front of the pipe
      > enclosures (pipe chambers) to increase and decrease the volume of sound
      > produced by the pipes which is allowed out into the room. These resemble
      > venetian window blinds. They are slats which are pivoted about a center
      > point and connected by means of a rod (known as a "trace") attached to
      > the leading edge of each in such a way that they open and close together.
      > To actuate this movement and be controllable by the organist we reason
      > that a servo motor would manage quite well. The arm (horn) of the servo
      > would be attached to a linkage which terminates the rod (trace)
      > mentioned above. We have studied and identified a servo (for example the
      > Futaba S3306MG _http://www.servocity.com/html/s3306mg_servo.html_ would
      > seen to fill this purpose.) My intent is to use a small organ we own
      > currently under refurbishing in our shop as a test-bed. In the first
      > incarnation of the design I am thinking a hard-wired version would be
      > most prudent. Later as the concept is more proven a wireless version
      > might emerge.
      > _My questions are as follows:_
      > What controlling components would be appropriate and compatible with
      > this unit?
      > [Referring to Jeremy Blum's Arduino tutorials on YouTube; I can see that
      > a potentiometer of fairly high resolution coupled with an Arduino and
      > accoutrements could manage this probably if the correct marriage of
      > hardware were selected together with the correct and most succinct
      > programming.]
      > We have been studying an "Arduino" type control as the simplest possible
      > solution to this relatively simple problem. I envision a simple
      > potentiometer at the shaft of the pedal connected to an arduino and
      > appropriate accompanying components connected to a power supply in the
      > console (the location of the pedal) (A p/s is required at that location
      > anyway for other purposes.) that would then be connected to the servo,
      > etc. in the organ case (the location of the louvers) with its power
      > supply (a p/s is also required in that location also for other
      > purposes.) The aim of such would of course be that the servo would
      > precisely follow the movements of the potentiometer at the pedal shaft
      > which would be no more than 90 degrees. What are your thoughts and
      > suggestions?
      > If you could advise me it would be greatly helpful. If my explanation is
      > unclear or you need further detail or clarification just let me know. If
      > this topic is not appropriate to the group any interested member may
      > contact me off-site at my email it this is more acceptable.
      > Michael Way,
      > Engineering,
      > Puget Sound Pipe Organs, Seattle, WA USA
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