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  • Interfacing with Allen Capture System

    I've been planning for the next phase of working out how to get the combination action of my Allen to interface with Hauptwerk. I have tested the stop mechanism, and I found that if a current is going to the middle pin of the three pin solder connections at the bottom of an individual stop (thin green wire), then if the stop is selected and the pulse is activated, it will pull it up, and do nothing if it is already up. If the stop is not selected, and no current is going to the middle pin, then the current pulse will pull it down. Otherwise, it will leave it down. The first and the third pin appear to be where the current pulse goes in and out. So, my plan is to wire each middle contact to the pins of a MCP23017 I/O expander. The circuit only draws ~4 mA, at 5V, so I think the MCP23017 should handle it fine. I have a small Nano Every, which has the I2C pins, so that is what I will use to connect to them. To activate the pulse for the combination action, my plan is to wire one of the Nano Every pins to a relay, then to ground. On the other side of the relay, my plan is to wire the leads of one of the current pistons that activate the capture action pulse. I decided to separate the capture action from the Mega I'm using for keying, since I don't want the capture action program and slow MCP23017 pins to slow down keying. My plan is to totally separate Midi input on the Nano Every from the Midi output on the Mega, and to use the mega to read the state of the stops and pistons and send them to Hauptwerk via MIDI out, and the Nano Every to read MIDI input stop state messages coming from Hauptwerk.

    My questions have to do with the relay. I have some 5V 10 amp relays coming. I will test the leads of the switch I'm planning to use to make sure it isn't too much for the relay, and if it is, I'll buy some automotive relays. However, I'm wondering how long to switch over the relay for in the Arduino program? I thought I could start short, say switch the pin to OUTPUT and HIGH, then delay for 50 micros, then switch back to INPUT, and see if it is enough to trigger the pulse, then keep increasing until it works, but anyone more familiar with how the Allen capture action operates would save me a lot of trial and error. Given how thick the wires are, I'm wondering if the full current going to the stop mechanisms also goes through the control switches. However, I'm not sure if there is a circuit in the capture action power supply to limit the duration of the pulse? Is anyone is aware of whether the capture action does in fact limit the duration of the pulse? Also, any thoughts about pros and cons of my circuit design would be appreciated! Thanks in advance!

    -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
    -Website: https://www.exercisesincatholicmythology.com

  • #2
    Knowing the model and number of stops you plan on supporting would helpful. The current draw can be quite substantial. Activating my combination action causes the house lights on the same circuit to dim. Keep in mind that with the Allen system, current is applied to one coil of every stop even if that stop is already in the desired state when a combination is activated. For example, if the stop is up and the combination calls for the stop to be up, current will still be applied to the up coil of that stop. I don't recall the voltages involved, but they are in the 40 - 50 vdc range. The no longer available Zuma solution for DM capture systems as well the DM solution under development by John Kinkennon leverage the Allen Capture supply for this purpose. I would not consider using a relay for this purpose.
    -Admin

    Allen 965
    Zuma Group Midi Keyboard Encoder
    Zuma Group DM Midi Stop Controller
    Hauptwerk 4.2

    Comment


    • #3
      Thanks Admin. I have a MOS-2 225 RTC with 54 stop tabs. My thought was not to use the power supply directly, but to interface the Arduino with an existing piston to trigger the capture action. I agree if the full current goes through the switch a relay may not work, but surely there is a way to trigger the pulse without needing to go through the full voltage?

      -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
      -Website: https://www.exercisesincatholicmythology.com

      Comment


      • myorgan
        myorgan commented
        Editing a comment
        Larason2,

        I would think that in order for the stop tabs to move on your organ, it would STILL require the same amount of voltage to turn the stop on or off. I do know that on Allens of that vintage, moving stops are required to change the registration. It may work differently on Allen's blind capture organs, but moving stoptabs and/or drawknobs will require the full voltage.

        Michael

    • #4
      Since it's a DM system, you should use the existing Allen Capture Power supply. There are four banks of outputs that drive the stops and those are triggered by a logic level signal. At this point in time, I'd be waiting for John Kinkennon s solution, but if you want to do it yourself, I think you'll find some information on how to do this on his project website. I believe there's also a discussion on interfacing to the supply on the Forum as well. Search on Allen Capture Power Supply.
      -Admin

      Allen 965
      Zuma Group Midi Keyboard Encoder
      Zuma Group DM Midi Stop Controller
      Hauptwerk 4.2

      Comment


      • #5
        Let me remind everyone that my code is available on www.kinkennon.com right on the home page until I get around to making some web site updates. The code is for the Teensy 4.1 which is a relative of the Arduinos with some improvements so 95% of the code is Arduino. Technically it is Teensyduino.

        Set the green wires to the logic level you want. 0v sets a stop to turn on and 5v sets it to turn off. To cause the stops in a division to actually move pull N1, N2, N3, or N4 low from an open collector device for 50ms. Each Nx on the capture supply pulses voltage to one division of stops. I connect to the stops through a 1k resistor.

        I used the 23017 devices with Allen stops for years and it's a great choice.

        As an aside my "pistons boards" for the J80 connection are finally with DHL and on their way from Hong Kong.
        http://www.kinkennon.com

        Comment


        • #6
          Thanks for your reply John! That’s very helpful. I feel like I should be patient and wait for your boards though, especially since they will allow me to keep the original function, which was one of my project goals. It’s good to know if the capture board ever stops working I have a backup though! Thanks again for all your help.

          -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
          -Website: https://www.exercisesincatholicmythology.com

          Comment


          • #7
            Hi John,

            I was wondering if I could ask you a few more questions! I got impatient, and I ended up wiring the pistons and stop switches in a matrix using the MCP23017’s. The plan now is to wire all the green wires to other 23017’s to complete the combination action. I have some questions, however about triggering the power supply. I’m planning on buying some TO-257 transistors, which are rated up to 100v and 15 amps. Should I use one of these for each Nx wire, or can I wire them all to the same one? Also, do you add the 1k resistor between the positive voltage of the power supply and the transistor? If so, what wattage did you use? Would 10 watt be enough? Thanks!

            -Current Instruments: Allen Mos-2 225 RTC,1870's W. Bell Reed organ, 1890's Singer Chicago upright grand piano Former Instruments: Yamaha Electone E3R
            -Website: https://www.exercisesincatholicmythology.com

            Comment


            • Admin
              Admin commented
              Editing a comment
              If you're using the Allen capture supply, you don't need power transistors to pulse the Nx lines. You just need to pull them low with an open collector device. Any logic device should be able to handle the voltage and current requirements. I used 23017 devices for this purpose. 1/4 watt resistor will suffice.

            • Larason2
              Larason2 commented
              Editing a comment
              Thanks Admin! It’s much simpler than I thought then. When I saw the wide gauge wires I assumed they were carrying some heavy voltage, glad to see not quite!

          • #8
            Since you are working on this project I'd be happy to send you a set of five small boards. They are working so far as I can tell without actually trying them in an Allen MOS-2 organ and you can try my software and improve it as you see fit. Do I have your email? I'm sure I don't have your address, so look up my contact info on my web site and send me the address. I'll include the programmed Teensy 4.1 -- just keep us informed of how it works out and any changes that were needed.
            http://www.kinkennon.com

            Comment


            • Larason2
              Larason2 commented
              Editing a comment
              Thanks John! I believe we have exchanged emails already. I’ll send you a reply to our last email. Cheers!

          • #9
            Here's an update. Larason2 has kindly agreed to try out a beta version of my Allen Capture boards. Sure enough we discovered a serious error on my main board, a reversal of the power leads at the edge connector! That's an easy workaround but at least some of the boards did not survive. It appears that the Teensy 4.1 is OK but in any case I am about to send a second set of five boards plus the Teensy 4.1

            We also found a problem with the way the Teensy allows for isolating the 5v power from the USB jack from the 5v In jack which means that powering the boards remotely requires another workaround.

            This setup is identical to the capture system used on my recent ADC-8000 conversion except that the signals were all brought out to edge connectors to convert to a simple plug 'n play approach. So I am not expecting more problems as the setup tests fine except that I did not provide 5v power via the edge connector. These things are never simple! Stay tuned!

            Click image for larger version

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            And a big thank you to Larason2 for your able assistance -- will send the boards today or tomorrow!
            http://www.kinkennon.com

            Comment


            • #10
              Watching this development with great interest. Keep us informed of your progress.
              Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI.

              Comment


              • myorgan
                myorgan commented
                Editing a comment
                I'll ditto Larry's statment. I'd offer to try it in some of my ADC organs, but they won't be set up in my garage until late June at the earliest.

                Thanks so much for this project!

                Michael
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