Keyboard Mechanical Design

[Gene & Debby Stopp]

> From: Ken Stone <sasami at blaze.net.au>
> To: synth-diy at horus.sara.nl
> Subject: Re: Keyboard Mechanical Design
> Date: Monday, August 25, 1997 10:01 PM
> 
> >
> >> but I'm at a loss as to what to do about the physical keyboard
> >> (i.e., the keys) itself.  Can you buy a mechanical keyboard, like you
can
> >> with computer keyboards or touch tone telephone keypads?  If so, who 
> >> would carry these?  If not, then how do people generally build them
(what 
> >> kind of switches should be used,
> 
> My solution? Take valuable vintage synth and remove keyboard. Wire in own
> circuits as required.
> 
> Before the rocks get thrown at me, I will add that keyboard #1 died some
> time back in 1982 or 1983 when a) it wasn't particularly valuable, and b)
I
> couldn't afford to repair it. Keyboard #2 was cut from the SH5 that now
> features as a rack mount module in the bigger picture, also cut out when
the
> synth was of no value. I couldn't even sell it for $100. It now features
> hall effect sensors that can be addressed by a microprocessor port to
give
> polyphonic readings. Basic on/off though. No velocity or pressure
sensing.
> The original 1v/8va stuff is also still on this keyboard.
> 
> Use MIDI if you want to, and it may well suit your purposes. Personally I
> hate MIDI (blind prejudice) and won't use it at all. 
> It's an 8 bit bus or it's nothing for me. I might add that neither
keyboard
> has seen light of day for several years, as I don't use them!

Good point about the vintage machines - most of them are in "fair"
condition by now, and the contacts in the keyboards are beyond the point of
ever getting back to their original cleanliness. So their keyboard
interfaces suck big time (I'm talking about the
current-source/resistor-string/sample&hold types, which covers most of the
cool ones). So hacking them into rack boxes is a viable option.

However, the trick I prefer is building a little digital scanner plus DAC
type interface on a suitable small piece of vectorboard and tucking it
inside somewhere, keeping the original keyboard, and thus preserving the
totality of the machine's original charm. The digital scanner type of
interface can usually work with even the suckiest contacts, plus there is
no S/H leakage problems. All around a better solution even if the machine
still plays okay. Yeah yeah I've said it before, I know, I'm like a broken
record.... you know, those vinyl things? Geeeez I'm showing my age.

Anyway for example I have a nice old old old minimoog, all transistors and
clear wheels, no mods except for this perfectly accurate keyboard... people
crowd around that thing man....

But I digress - sometimes the keyboard mechanisms are just not available
for the DIY'er, and so you must resort to MIDI. As for MIDI-CV converters,
here's an idea: hang out by the dumpsters of a computer repair shop. Pick
out the occaisonal 486/66 motherboard, which will be perfectly good. Run
over to Fry's (or similar computer superstore) and grab a $19 sound card
with MIDI, plus one of those game port to MIDI cables. Slap a power supply
and a floppy on it, stick a DAC on the parallel port, write some code in
QBASIC and put it on a bootable floppy in autoexec, and instant cheapo
MIDI-CV converter.

- Gene