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toe piston 3 contacts, why?

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

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toe piston 3 contacts, why?

PostTue Jan 05, 2021 8:27 pm

I am midi-fying an old pedalboard of unknow manufacture. the toe pistons have 3 contacts that touch a copper plate in sequence as the piston is pressed. The middle contact touches first, then the left contact, then the right contact. Once a contact touches, it stays connected, so when the piston is fully pressed all three make contact, When the piston is not pressed, no contacts touch. (sorry, can't figure out how to post images)

I am thinking the middle contact is power or ground and the other two are the signal. Is this correct? Is this some kind of debounce method? I can't think of any kind of simple flip/flop setup that would work, since this isn't a double throw.

Thanks in advance
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NickNelson

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Re: toe piston 3 contacts, why?

PostWed Jan 06, 2021 1:04 am

This sounds more like a 'second touch' arrangement to me.

Something similar is described in 'The Electric Organ' by Reginald Whitworth, 1940, p122.

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johnstump_organist

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Re: toe piston 3 contacts, why?

PostWed Jan 06, 2021 11:52 am

Could have been a backup system in case one contact became corroded or failed. Or if it was an old analog pneumatic system there might have been three banks of pneumatic memory cogs to send signals.
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EricJ

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Re: toe piston 3 contacts, why?

PostWed Jan 06, 2021 9:04 pm

I hadn't heard of second touch before, but after reading about it, that makes sense. I guess I have a pedal board from a Theater organ. :wink:
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organsRgreat

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Re: toe piston 3 contacts, why?

PostThu Jan 07, 2021 7:00 am

To hear how a great theatre organist used second touch on the manuals, have a listen to this youtube video:

https://www.youtube.com/watch?v=KwOc07U7vhA

Reg was able to play melody and accompaniment with his left hand on one manual, leaving his right hand free to extemporise a counter-melody.

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