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DIY lighted stop tabs

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...
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polikimre

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DIY lighted stop tabs

PostMon Aug 17, 2009 10:46 pm

It's been a while that I've reported on my project of MIDIfying a Reuter Church organ console. The console has 41 engraved stop tabs, which I wanted to keep. I replaced the original switches with new, reliable microswitches, and installed a small 3mm LED in each stop tab. They are driven with a MIDIbox unit using two DOUT modules, using the MIDIO128 firmware. There is no logic inside the console, everything is processed by Hauptwerk, this switches generate MIDI events, which causes HW to send back another MIDI event to turn the lights on or off. This makes it easier to keep things in sync.

It has been a lot of tedious work, but tonight I was able to try it, and it works great (I used HW in eval modefor the test). The light was in perfect sync with the stops on the screen (tried combinations, cancel, crescendo, etc.)

Image

More pictures with explanations are at here.

PS: I really need to upgrade to HW Advanced now. Good thing my wedding anniversary, birthday and namesday are all coming up soon. I know what I want.
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engrssc

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Re: DIY lighted stop tabs

PostMon Aug 17, 2009 11:17 pm

That is one piece of good work, Imre, congratulations! The photos get the message across excellently as well

A couple questions: Is there any additional spring installed to return the tab to it's normal (off) position other than the spring of the micro switch itself? How are the micro switches connected, thru a MidiBox DIN?

Do you use a separate power supply for the LED's? Have you had all of them on at one time? How is the temp of the driver chips with all of them on? I read an article where the suggestion was made to use every other (LED/chip) driver.to better dissipate the heat.

How did you setup Hauptwerk? Can I assume that touching a stop tab the first time turns the stop on and the second time, turns it off? Are the tabs fairly responsive, by that I mean, can you make quick changes and even "glide" your finger across several stops rather than pressing each stop individually and more slowly?

I would assume the system works with a combination action piston as you mention using the crescendo working with it. Now that's quite a good feature to say the least.



Again, great job,
Rgds,
Ed
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GrahamH

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Re: DIY lighted stop tabs

PostTue Aug 18, 2009 4:40 am

Congratulations Imre!
That is a beautiful piece of work, and the photos are really helpful.
Unfortunately my stop tabs don't lend themselves to the same kind of modification, and in any case I haven't enough of them, so I'm experimenting with a different kind of switch. But if/when I solve that issue, I'll PM you for some info about the MIDI Box kit which looks very neat.
Regards
Graham
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polikimre

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Re: DIY lighted stop tabs

PostTue Aug 18, 2009 5:39 am

Thanks for the compliments guys.

engrssc wrote:Is there any additional spring installed to return the tab to it's normal (off) position other than the spring of the micro switch itself? Are the tabs fairly responsive, by that I mean, can you make quick changes and even "glide" your finger across several stops rather than pressing each stop individually and more slowly?

Right now there's no spring installed. The tabs (simply by their weight) sit as low as possible, the metal thing at the back of the tabs just touches the microswitch. The travel of the switches with this setup is less than 1mm, it feels very natural, "stop glissandos" are easily possible. I'm thinking about installing small springs for each tab, but it may not be needed, I'll see how this setup works in practice.

engrssc wrote:How are the micro switches connected, thru a MidiBox DIN?

I use a hwce board from midiboutique. One channel for pedal, two for the manuals, one for stop tabs and switches.

engrssc wrote:Do you use a separate power supply for the LED's? Have you had all of them on at one time? How is the temp of the driver chips with all of them on? I read an article where the suggestion was made to use every other (LED/chip) driver.to better dissipate the heat.


I haven't measured the total current yet, that's coming today. For this reason also, I only had them on one by one. They draw about 15mA each. Even with 41 LEDs that should be safe. My power supply for the MIDIbox is 9V 1A. I'll check the temperature of the drivers as well, thanks for the tip.

engrssc wrote:How did you setup Hauptwerk? Can I assume that touching a stop tab the first time turns the stop on and the second time, turns it off? I would assume the system works with a combination action piston as you mention using the crescendo working with it.

The stop switches are "Repeated event toggles" type, as they are momentary switches. The console itself is passive, everything is done by Hauptwerk. When the state of a stop switch changes in Hauptwerk, it sends out a MIDI message, which is captured and decoded by the MIDIbox unit, and the state of the lamp is changed accordingly. The stop switches on the console are just another way to change the state of the stop switch in Hauptwerk. Having it with crescendo or combinations is simple matter as the stop switches in Hauptwerk don't know why they have come on. Whatever way they come on, the MIDI message to set the lamp on is generated. This seems to me the cleanest setup. The only disadvantage is that I can't use the console without Hauptwerk. Why would I want to do that?[/quote]
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engrssc

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Re: DIY lighted stop tabs

PostThu Aug 20, 2009 10:47 pm

I reread your post again (with interest) and had a thought regarding the metal "lever" that press the micro switches, that being I wonder if there should be a travel stop to prevent accidental pressing the m/s too hard and possibly damaging it. It appears there is some mechanical advantage to the present arrangement.

Rgds,
Ed
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polikimre

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Re: DIY lighted stop tabs

PostFri Aug 21, 2009 7:25 am

I have a layer of green felt under the switches, which gives a bit of travel after the switch has been activated, and slows down the action. It also helps to dampen the quiet click of the switches (which would otherwise be amplified by the wooden frame the switches sit on).
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engrssc

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Re: DIY lighted stop tabs

PostFri Aug 21, 2009 7:29 am

Good plan, I just didn't see that in the pix.

Rgds,
Ed
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polikimre

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Re: DIY lighted stop tabs

PostSat Aug 22, 2009 9:17 pm

A quick update: With all 41 LEDs on, the total current through them is 500mA. This is very good news, as I can power my MIDI in and out boards from the same power supply. One LEDs consumes abour 12mA, while they are good until 30mA. As they are operating at such low current, the driver ICs are not warmer than room temperature.

Next project: MIDIfy the swell and crescendo pedals. The hwce board from MIDIboutique takes a 10k pot, but I couldn't find a slider type, linear taper one. I have a logarithmic slider, and a linear rotating one. Any tips?
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engrssc

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Re: DIY lighted stop tabs

PostSun Aug 23, 2009 1:35 am

Will have to look, but my recall is I used pot(s) from Mouser. Electronics Mechanically you can see my setup on the second page of this post: http://site.virtualorgan.com/community/viewtopic.php?f=40&t=694 So far it has all worked great.

Rgds,
Ed

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