[sdiy] optical retrofit for minis?

[doof]

I think this is a wonderful idea, and would most certainly be one of your
first buyers if it develops into something concrete.

The most important point is a reliable keyboard that doesn't require
constant cleaning and maintenance.  If it functions identically to the stock
mini keyboard, albeit reliably, I would say it's money well spent.  The
additional bells and whistles would likely only drive up the cost and
complicate installation.  From my perspective, a diy drop-in replacement
would be the most appealing route of upgrading.  I like your idea of
offering a basic model and a premium model (for those that can afford a
professional installation).  Something tells me the first type would be a
better seller though...

Just some thoughts.. I wish I had the expertise to help out.

Best of luck.

----- Original Message -----
From: "Kevin Lightner" <synthfool at synthfool.com>
To: "synthdiy" <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, March 22, 2005 11:55 AM
Subject: [sdiy] optical retrofit for minis?


> Lest I never complete a project that I desperately need to have done,
> I'd like to share what I've been spending a fair amount of time on
> lately. Any practical help would be hugely appreciated.
>
> Here's the situation:
>
> Minimoog keyboard actions are dying left and right.
> More and more frequently, the plating on the contact springs and
> bussbars are wearing through, springs stretched, buss bars bent and
> the rubber standoffs on the contact board hardening. I have several
> minis here, all with restored electronics, but with bad keyboards.
> The clients are looking into options (buying another mini for parts,
> MIDI, etc.)
>
> I want to offer both my direct clients and as saleable product to
> anyone else (discounted to service centers), a drop-in board with
> photo interruptors. The idea is sound and possible to do.
> The SCI T8 and Synclavier did this also.
>
> So, I ordered some various interruptor devices and found one that
> meets all my needs in terms of price, availability, current draw, etc.
> Then I made a small prototype from an old Mini action and tested it.
> By using the original white, L shaped contact actuators or "pullers"
> as a shutter, the sensors worked great. No additional goodies would
> need to be added or even these white pieces requiring blackening.
> During the experiments, I also found that an incredibly controllable
> aftertouch is also possible, similar to the scheme used in some
> Polyfusion keyboards.
> While the optosensors I used specified a much higher current draw for
> their IR led, I found that it would still reliably work *much* lower
> too. So, 44 could conceivably be powered at the same time, if
> scanning wasn't implemented.
>
> A PIC could be used for this project and if time was spent on some
> additional programming, I figure the following features could also be
> added:
>
> 1. Transposition
> 2. Inversion
> 3. Various scales
> 4. High, low or last note priority
> 5. Midi in and out (out being rather rare as a feature on minis)
> 6. Arpeggiator (lots of work, but possible)
> 7. Velocity and aftertouch (possible, but likely not easy to implement.)
> 8. Glissando
> 9. Single/multiple triggering
>
> Several other possibilites too, but these are off the top of my head.
> Even an autotune could be made if the thing was taken to the nth degree.
>
> Ideally, a PIC would either have enough I/O lines for every key
> directly, or have enough lines for decent mult/demult schemes with
> additional ICs, one or two 16 bit DACs, a timer or two and draw very
> little current. I've found such a processor, but have no development
> tools.
> A fast clock rate and a timer would aid in providing dynamics, which
> *can* be done with just one optosensor.
> I understand machine code programming better than I understand a
> windows interface though ;-)
> Programming one here would be an expensive ordeal and take considerable
time.
>
> Programming of various modes for the user would be via holding down
> the topmost and bottommost keys for 2 or 3 seconds, then making a
> selection via another key. Sort of how the OSCar does theirs.
> This, so no additional controls are added.
>
> Another solution would be installation of a Fatar action.
> They're cheap, but I feel many people wouldn't want them in their
> model D minis.
> Don Martin of Moog Music Cincinatti used this and a small board for
> scanning and D/A, but I never documented his work close enough
> regarding this board and don't have a Donimoog to copy.
> He had a 20 pin IC in his though, so I'm assuming he had a small PIC
> in there himself.
>
> Other solutions are welcomed, though if a laser is suggested, a
> solution (two lasers?) would be needed for note priority. A modulated
> laser could identify what note was pressed by pulse counting/timing,
> but once a shutter (key pressed) is made, the beam would be broken
> and note priority would be lost.
>
> So here's the deal: I need some help. Programmer, engineer, board
> person, financer.
> I could do it all, but it would arrive *very* slowly.
> If any folks on the list feel they would like to contribute to the
> project, I'd be most happy to hear from them. Unfortunately, all work
> would be on spec. That is, payable after the project turns a profit.
> Or I could trade them parts, etc, depending on what I have.
>
> With roughly 13,000 minis made, and obviously many that gave their
> lives, visited Studio Electronics, sitting in closets or whatever,
> I'm guessing there may be 100-600 potential customers for the product.
> Priced correctly, the product could still turn a tidy profit even on
> these small numbers though.
> The action would never need cleaning, would feel better (it doesn't
> have to pull contact springs any longer) and would offer several
> attractive new features.
> I have a ton of customers right off the bat.
> Two models could even be offered. A bare bones "just the notes" model
> and a "bells and whistles" model with all features. A upgrade rom or
> USB interface could turn the former to the latter, as well.
>
> Any thoughts? Advice? Contributions?
> Keep in mind, I've been thinking about this concept for a long time
> and already have done considerable footwork. The concept works. I
> just don't have the resources. :(
>
> Finally, a passive, switch only board for Taurus 1's needs to be done.
> I may do this myself, but if anyone would like to chime in on this
> project feel free.
> In case you're not aware, the T1 has a huge, inherent design flaw:
> every switch contact must be normally closed or any pedals above an
> open contact won't play. Since the switch contacts are silver and
> tarnish easily, this is an often reoccuring problem where the higher
> you go on the pedal board, the more chances of failure are presented.
> A single, long board (thicker than what Moog used) and long-life
> microswitches would do the job. Unfortunately, I don't have the
> equipment to even prototype such a long pcb. Any ideas on this would
> be welcome too.
>
> Thanks for listening and possible suggestions, etc.
> Investors are hugely welcomed also ;-)
>
>
> --
> Regards,
> Kevin Lightner
>
> Myself: http://www.synthfool.com
> Service and sales: http://www.moogmusic.com/service.php
> Sales: http://www.cluboftheknobs.com