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SAM Control Module:Version 2

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  • SAM Control Module:Version 2

    SAM Control Module: Version 2

    I wasn't totally happy with the code I published in my post on March 10. It left many pins unused, so I made the following changes which make the program substantially different and significantly more useful, enough to warrant a second post.

    1. As before, the module "talks" to 16 stops on a virtual organ and uses the stop change messages received in return to operate dual-magnetic draw knobs, or any SAM for that matter. What I added were 16 switch inputs that can be connected to pistons to operate the combination action on the virtual organ which in turn operates the physical draw knobs. This makes the module completely stand alone, requiring no other boards.

    2. There is now provision for daisy chaining these units together to whatever size is needed. One only needs to assign a different channel number to each module. The details are laid out in the documentation in the code, which again can be found on my website:

    https://sites.google.com/site/casava...ination-action

    3. I expressed some concern about the program refusing to run after power up. I think I located the source of the problem. Jeux d'Orgues outputs an Active Sense message every half second which befuddles the Arduino boot software that is designed to start program execution. The solution is to make sure the serial IN port is "quiet" during power up either by not connecting, in my case, the iPad until the Arduino is powered up and the little LEDs stop blinking, or, alternatively by turning the MIDI Shield switch to the Off position while powering up. The same applies when one uses the Reset button on the board.

    The usual disclaimer: This has only been bench tested. Please alert me to any problems should you decide to use this code.
    John

  • #2
    John, You mentioned that your bench testing this. Do you already have this connected to stop action magnets? Or are you only testing on the software side? If you have it set up to magnets I’d be curious to know what circuit you’re using to drive them from the Arduino. I wonder if some of the stock Arduino motor driver circuit boards on eBay would be sufficient to drive these you mentioned that your bench testing this. Do you already have this connected to stop action magnets? Or are you only testing on the software side? If you have it set up to magnets I’d be curious to know what circuit you’re using to drive them from the Arduino. I wonder if some of the stock Arduino motor driver circuit boards on eBay would be sufficient to drive these SAMS
    Eric Mack
    www.ThisOld340.com
    Rodgers 340 S/N 34341
    Los Angeles, CA

    Comment


    • #3

      I do indeed use LEDs to monitor the states of outputs, but in this case I felt it necessary to connect at least one (KA) draw knob unit to check:

      1. When the draw knob is physically prevented from moving, I needed to verify that the ON/OFF pulse shuts off after one second (it does).

      2. I needed to verify that if the draw knob switches state before the one second is up, the pulse is shortened accordingly. (It is) Watching the LED on the driver, I estimate that the pulse is typically only about a quarter second long.

      My wife was most impressed to see the draw knob "bop" back and forth as I operated the stop on the touch screen.

      The drive units I'm using I bought to drive some 2 amp solenoids. (Experimenting with building a Vorsetzer) These MOSFET drivers operated the solenoids admirably. They are overkill for use with the draw knobs. Here's the scoop:

      http://robojax.com/learn/arduino/?vid=robojax-IRF520-MOSFET

      Note that these units require the use of external spark suppressing diodes. The KA units make provision for that on the little PCBs attached. The MOSFET units have a small LED to indicate when it is on. Cost: One dollar CAD each.

      A friend successfully used ULN2003A driver chips to interface an Arduino to the draw knobs on a pipe organ. They are good for 500 mA, probably a bit more if only briefly pulsed as in this application. They have the spark suppressing diode built in, which is a great convenience. At 25 cents apiece, each chip contains 7 drivers. I bought a box full and will try them out when they arrive. They should mount nicely on a piece of strip board requiring no other components.

      https://www.amazon.ca/8-5x20cm-Proto...ateway&sr=8-70

      I will report on this after I get to try them out. It sounds like an inexpensive way of driving SAMs or chest magnets.
      John

      Comment


      • Eric Mack
        Eric Mack commented
        Editing a comment
        I will continue to follow. I have most of the parts, including a box of SAMs a friend gave me. Now I just need to find them.
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