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Midifying a keyboard

PostPosted: Sun Jun 23, 2019 1:50 pm
by Wall.e
Hello dear users,

I was lucky and bought 3 manuals from an existing church organ. I want to midiy them with an Arduino (as I already did with the pedal, stops, another keyboard etc..). I am not sure if I can use the existing wires and contacts from the manuals, I don't know if I need a power supply for them or whatever...
I post a link where you can see that every single key has 3 wires connected onto a rail where 1 wire goes off (I suppose for data?). Given that amount of wires, there are another 2 wires on the top of the rail and I have no idea for what purpose they are. Power supply and ground?
(Programming the Arduino so far was easy and on my projects I only had 2 different wires: 1 Ground and 1 data, so I have no idea if I can use the existing ones and in which way, or if I have to use magnets and contacts as usual...)

Here's the link:

https://www.dropbox.com/sh/rg9kgsjzv5ze ... 0-Tta?dl=0

If you know, how I can use them (for an Arduino) I would be very happy!

Best regards,
Walter

Re: Midifying a keyboard

PostPosted: Sun Jun 23, 2019 2:19 pm
by Grant_Youngman
If power was applied to the keyboard, it must have been related to whatever the original keying system was. Wouldn't need that for MIDI-only.

Have you checked which pair (s?) of contacts on each key close when you depress a key (with a DVM/ohmmeter of some kind)? All you need from the keyboard is a single identifiable contact closure per key, then wiring should be straightforward in whatever format you plan to use for your decoder. I can't make out the workings of the actual contact mechanism in the photos …

One of those two busses that run the length of the keyboard is (or could be used as) probably a common …. or cut in appropriate places into multiple commons for a matrix encoder, etc.

Re: Midifying a keyboard

PostPosted: Mon Jun 24, 2019 6:01 pm
by Coenraads
Hi Walter
As Grant points out, you only need one good contact per key, and if those contacts are gold or silver, you are good to go. If the contacts are phosphor bronze however, they will be iffy. I've had some success in a pedal board with multiple phosphor bronze contacts by simply wiring the multiple contacts in parallel where they are available for extra redundancy. Make sure to use some heavy duty debouncing in your code. But even then, unless constantly used, at five volts they will corrode and require regular cleaning. I eventually replaced them with Kimber Allen contacts although reed switches are a much cheaper way to go. Reed switches only work with pedal boards. Their hysteresis is too great to use with the limited travel on a manual keyboard. The alternatives are gold or silver contacts, optical switches or Hall effect switches.
If you scan down this subforum, you will see that in February and March of this year I wrote a series of posts dealing with the application of Arduinos to virtual pipe organs. I learned a lot from the ensuing discussions and you may find them useful too.
John

Re: Midifying a keyboard

PostPosted: Mon Jun 24, 2019 9:30 pm
by thomas690
Hi,
I red your consideration about MIDI in old keyboards. Please quick look on http://www.pipeorganlogic.com
We offer very easy to fit hall effect contact key
It is also movie on YouTube how they was fit in small organ and how it works. They allow to regulate electrically each key. Alternatively you can contact on info@pipeorganlogic.com.
Thomas

Re: Midifying a keyboard

PostPosted: Tue Jun 25, 2019 2:43 pm
by organtechnology
Wall.e wrote:Hello dear users,

I was lucky and bought 3 manuals from an existing church organ. I want to midiy them with an Arduino (as I already did with the pedal, stops, another keyboard etc..). I am not sure if I can use the existing wires and contacts from the manuals, I don't know if I need a power supply for them or whatever...
I post a link where you can see that every single key has 3 wires connected onto a rail where 1 wire goes off (I suppose for data?). Given that amount of wires, there are another 2 wires on the top of the rail and I have no idea for what purpose they are. Power supply and ground?
(Programming the Arduino so far was easy and on my projects I only had 2 different wires: 1 Ground and 1 data, so I have no idea if I can use the existing ones and in which way, or if I have to use magnets and contacts as usual...)

Here's the link:

https://www.dropbox.com/sh/rg9kgsjzv5ze ... 0-Tta?dl=0

If you know, how I can use them (for an Arduino) I would be very happy!

Best regards,
Walter


Hi Walter,

Grant's question is the key (pun intended) to the solution. At a key location which two of the three wires are connected together by depressing the key? You can check this with a simple Ohmmeter. If the resistance turns out to be high, then applying a voltage like 5 Vdc to the chosen 'common' wire and reading the voltage with the Arduino will give good results. A 'pull down' resistor may be useful in this case also.

or
you can remove the antiquated keying contacts and replace them with modern methods of keying such as optical, magnetic or Hall effect magnetic. This would be my choice but it is a LOT more labor and expense.

Thomas the builder.

Re: Midifying a keyboard

PostPosted: Tue Jun 25, 2019 4:14 pm
by NickNelson
organtechnology wrote: ... applying a voltage like 5 Vdc to the chosen 'common' wire and reading the voltage with the Arduino will give good results. A 'pull down' resistor may be useful in this case also.


Or, enable the pull-up resistors on the Arduino inputs (most have this option I think) and make the common 0V. Whether this works reliably is not certain, but maybe worth a try.

organtechnology wrote: or you can remove the antiquated keying contacts and replace them with modern methods of keying such as optical, magnetic or Hall effect magnetic. This would be my choice but it is a LOT more labor and expense.

I agree, though I also think that Hall effect is the only satisfactory magnetic approach.

Nick

Re: Midifying a keyboard

PostPosted: Tue Jun 25, 2019 5:05 pm
by engrssc

Re: Midifying a keyboard

PostPosted: Fri Jul 05, 2019 2:37 pm
by Wall.e
Hello,

thank you very much for your replies! I was working this week on midifying the keyboards and wasn't difficult at all. The keyboards are running on 5V provided from Arduino. The only really annoying and difficult thing was soldering nearly 200 small contacts on the Arduino boards!
When I was turning the keyboards into the final position some of the already soldered cables dissolved again...
But well, it's done now and I am really satisfied with the touch.
Thank you for all your advices.

Kind regards

Walter