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Pedal "position" indicator

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

Re: Pedal "position" indicator

Postby engrssc » Fri Aug 14, 2009 4:09 pm

The right angled 20 pin dual inline socket looks to be right for this project except I haven't yet found a source in the USA. There are 14 and16 pin, but so far can't find the 20 pin version here. The only other components would be the PCB and a bezel to make this a cool setup.
Rgds,
Ed
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Re: Pedal "position" indicator

Postby engrssc » Fri Aug 14, 2009 6:59 pm

I explained "our" project to Roman Sowa who is the supplier of
the POT32 http://www.midi-hardware.com/pot32.htmlwhich
I am using as the pedal pot(s) to MIDI scanner/encoder.
Here is his interesting response:

Use a voltage follower. That's a single NPN transistor circuit. Base to
pot's wiper, emitter to 1k resistor to ground, and the collector to +5V.
It won't be perfect, with dead bands at the ends of pot's travel, but
should be enough for bargraph driver.

I haven't checked, but if the LM input sinks a lot of current, you
may get curved pot response. It would be like you'd have audio
taper pots installed, which is not good for MIDI.

Of course try to connect it directly and check if you can notice a
difference in pot's response. You should get only 50% of MIDI value when
your pot is in the middle position


Rgds,
Ed
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Re: Pedal "position" indicator

Postby JimB » Mon Aug 17, 2009 9:23 pm

Ed,

Check with Roman. He has just introduced a small LCD display. It is not yet on his web site. I just received one with my controller and scanner boards. I plan to test it out as soon as the console is ready.
Jim Becker
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Re: Pedal "position" indicator

Postby engrssc » Mon Aug 17, 2009 10:16 pm

I have been interested in an LCD, but haven't pursued that interest just yet. Thanks for the heads up, Jim. Just curious, how did you find out about the new product? I have been in touch with Roman and he hasn't mentioned anything.

Rgds,
Ed
Last edited by engrssc on Tue Aug 18, 2009 9:46 pm, edited 1 time in total.
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Re: Pedal "position" indicator

Postby JimB » Tue Aug 18, 2009 9:22 pm

Ed,

I asked many questions about my proposed setup. I guess he though I might be interested.
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Re: Pedal "position" indicator

Postby NickNelson » Fri Aug 21, 2009 3:48 pm

Hello everyone,

If there's still interest in the (still unfortunately bezel-less) LM3914 approach to this, here is the result of some further work I've done. You will see that, by mounting the display in a rather unorthodox fashion, I have kept the circuit within the 'footprint' of the display. There are now adjustments for the full scale sensitivity (the 100k pot) from 1.25V to over 12V, and the point at which the first LED comes on (the 5k pot) from 0.5V to about 1.5V. These two adjustments are independent, and ought to accommodate most expression pedal setups I think. V+ can be anything from 5-15 volts or more. The longest dimension of the display is almost exactly 1" (2.54 cm) for scale.

ImageImage

For the reasons explained in my earlier post, it is configured to work in 'dot mode', but if you wanted it to work in 'bar mode' (and are sure you can supply the necessary 150mA or so) just connect pin 9 of the LM3914 (the only pin not connected to anything else at the moment) to V+

The design works equally well for the red and green displays, and should be OK with the yellow ones too though I haven't got any of these to test it with.

Below is a (rough - I'm sorry) picture of the copper (green) side of the PCB with the components (red) indicated as well. Please note that the anodes of all 10 LED segments have to be connected together and to the pad marked 'led+' on the PCB.

Image

If anyone wants a high definition version of the layout (suitable for printing transparencies to make the PCB) it is here:

http://www.personal.leeds.ac.uk/~edu6nwn/midistuff/ledbar.lay,

but unless you have the PCB design software "Sprint-Layout 4.0" you will need to use this:

http://www.personal.leeds.ac.uk/~edu6nwn/midistuff/viewlayout40.exe to view and print it.

Please note that I have no interest in making any of these boards/assemblies in quantity since a) it's very boring and b) neither my eyesight or
manual dexterity is really up to it any more. However, I might be persuaded to provide a very few for regular forum contributors if asked
nicely enough. I've not costed them, but could do if necessary on a not-for-profit basis.

Nick

ps It might be appropriate to move this thread to the 'DIY consoles' section?
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Re: Pedal "position" indicator

Postby dalest » Sat Aug 22, 2009 6:24 am

THANK YOU VERY MUCH .

but could you explain how i can put in on my pedal : i'll have an Hoffirchter organ with 3 pedal : 2 for "swell pedal" and 1 for crescendo.
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Re: Pedal "position" indicator

Postby NickNelson » Sun Aug 23, 2009 3:41 pm

dalest wrote:but could you explain how i can put in on my pedal : i'll have an Hoffirchter organ with 3 pedal : 2 for "swell pedal" and 1 for crescendo.


As I know nothing about this (or indeed any other) organ, I'm sorry to say I can't advise how or even if the module could be connected.

All I can say is that if you can provide a DC supply between 5 and 15 volts at around 20mA, the bargraph will respond appropriately
to any varying voltage applied to the input connection.

Nick
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Re: Pedal "position" indicator

Postby mdyde » Sun Aug 23, 2009 4:25 pm

I've moved this topic to the DIY forum area, since it seems most at home here.
Best regards,
Martin.

[Please use email or the Contact page if you need to contact us privately, rather than private forum messages.]

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Re: Pedal "position" indicator

Postby TheOrganDoc » Sun Aug 23, 2009 4:54 pm

Hello Nick,

I would like to install a pair of these indicators on my console in the near future.

If you can find someone that would etch two of these PC boards for me I will surely compensate !

I have not etched boards in 50 years.........! ! !....... :roll:
Mel..............TheOrganDoc...............
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Re: Pedal "position" indicator

Postby engrssc » Sun Aug 23, 2009 5:21 pm

As for one method to mount inline pots, you can check what I did here on the second page:http://site.virtualorgan.com/community/viewtopic.php?f=40&t=694

Rgds,
Ed
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Re: Pedal "position" indicator

Postby wurlitzerwilly » Sun Aug 23, 2009 6:10 pm

TheOrganDoc wrote:Hello Nick,

I would like to install a pair of these indicators on my console in the near future.

If you can find someone that would etch two of these PC boards for me I will surely compensate !

I have not etched boards in 50 years.........! ! !....... :roll:

Mel.

Why not use Veroboard and simply cross-wire with Kynar wire?
Regards,

Alan.
(Paramount Organ Works)
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Re: Pedal "position" indicator

Postby TheOrganDoc » Mon Aug 24, 2009 1:05 pm

"Thanks" Alan,

I will do that if no one else replies,

Last time I used Kynar wiring was building a 12 stop diode matrix some 35 years ago.......!

We certainly have come a long way since then, haven't we....(CODM).......?........ :?

Mel
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Re: Pedal "position" indicator

Postby NickNelson » Mon Aug 24, 2009 3:12 pm

TheOrganDoc wrote:I will do that if no one else replies


Hi Mel,

I sent you a private message early this morning, maybe you haven't seen it yet?

Nick
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Re: Pedal "position" indicator

Postby TheOrganDoc » Mon Aug 24, 2009 8:24 pm

Thank you Nick,

I have since sent you a PM, sizable time difference....!

I do appreciate you're help... :D .

I notice that you live, quite a bit East of here, a bit over the water !

Best wishes to you,.........Mel
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