An Arduino Pipe Organ

[Coenraads]

This week, an 8-rank pipe organ became available from a local church. Some friends are considering salvaging the instrument to save it from the landfill. Although it has some decent pipework, the control system is a phosphor-bronze mess. This may provide me with the opportunity to test my ideas for an all Arduino pipe-organ control system. Although I have implemented bits and pieces here and there over the years, this will force me to tie it all together.

I've decided that the work should be divided, one unit per division, where a unit consists of three Arduinos and its associated drivers. The diagram shows the conceptual organization for an organ of up to 30 or 40 ranks.

Arduino #1 operates the combination action as described in an earlier post.
Arduino #2 handles the keyboard scanning, stop control and coupler switching.
Arduino #3 decodes the serial stream of note ON/OFF data. Where the data do not apply to that division (as a result of coupling) it is sent serially to its neighbour until it "finds" the correct division.

Whether the console is worth salvaging or whether to adapt an Allen console remains to be seen.



Organ Control System.pdf

[Coenraads]

[gtc]

Interesting project. Any chance of some photos of the organ?

[Coenraads]

This organ is typical of the inexpensive organs builder Hugo Spilker put together for several of the churches in our city. Although not of the best construction, they have served these congregations well. Try this link:

https://www.google.com/maps/uv?pb=!1...oiowFHoECEMQAw

[Larason2]

Cool project, I wish you all the best!

[michaelhoddy]

I'm sure you'll have the control side of things nailed down completely.

The tricky thing with pipe organs is more the high-current stuff like magnet drivers, and then of course the actual action itself- stop actions, chest valves, etc. Is the organ currently direct-electric action (one electromagnetically-operated valve per pipe), or something else? Direct electric has higher current requirements than electropneumatic actions, but is far simpler to deal with in a retrofit.

[Coenraads]

I believe the chests are electro-pneumatic, probably 90 ohms. The stop tabs are dual magnetic and will require about half an amp. I like to use ULN 2003 drivers or its positive drive equivalent. For the stop tabs I'll parallel 3 drivers and put the ON and OFF coils on the same chip. When experimenting with building a vorsetzer for a piano, I used these same chips to drive some hefty 1 amp solenoids (paralleled of course) and could detect no sign of stress.

At the moment I'm working on refurbishing an old Devtronix switching system that uses an equivalent chip and it drives the Casavant's primary magnets just fine.

The nice thing about these chips is that they are Arduino compatible, so there is no additional circuitry except for the driver chips.

Thanks for the heads up.