[sdiy] 61 Note Keyboard from Electronic Goldmine

[Tim Parkhurst]

Hey Scott,

How difficult would it be to cut one of those keyboards down to three
octaves? This just might be the ticket for a replacement in (yet another)
ailing Odyssey I'm working on. Yeah, I know it'll need a micro to get it
working, but that still might be easier than cleaning the #*&^%@*&^@ contact
wires every month! Either that, or I'm thinking of slotted optical switches
(the main purpose of doing this is to keep the Ody as a self-contained unit,
and it really needs a more robust keyboard).

Tim Servo

"Imagination is more important than knowledge." - Albert Einstein

www.home.earthlink.net/~timservo2

**********************************************
> -----Original Message-----
> From: Scott Stites [mailto:scottnoanh at peoplepc.com]
> Sent: Thursday, June 19, 2003 12:30 AM
> To: synth-diy at dropmix.xs4all.nl
> Subject: [sdiy] 61 Note Keyboard from Electronic Goldmine
> 
> Hi all,
> 
> I ordered one of those 61 weighted key keyboards from Electronic Goldmine,
> and received it tonight.
> 
> http://sales.goldmine-elec.com/prodinfo.asp?prodid=8280
> 
> For $39.95, it's not a bad buy at all.  Each key does have a metal weight
> in
> it, and it's spring action.  It's got a good feel to the keys, but I
> really
> don't have anything good to compare it to.
> 
> The switches are the membrane type, and there is something about this
> keyboard I didn't expect:
> 
> The diode matrix has 122 diodes - two diodes for each key.  The columns
> are
> attached to the anodes of the diodes in pairs for each key.  The cathodes
> each are switched into two different, separate rows by the keypresses - in
> other words, there are twice as many rows as a 'standard' diode matrix.
> The
> rows are as one would expect - 8 keys to a row, except for each 8 key row,
> there is a duplicate 8 key row that is switched in separately with the
> 'second' diode.
> 
> The membranes are cup shaped.  Around the 'rim' of the cup is one
> conductor
> which switches one diode.  In the 'bottom' of the cup is another conductor
> which switches the other diode.  Now, I'm not sure about this, but it
> seems
> that the 'rim' conductor switches the first diode earlier in the travel of
> the key, and the diode in the 'cup' switches the other diode later in the
> travel of the key.   This could be my imagination - I'll know better when
> I
> can put two DMM's on it and check, but judging by eye, that seems to be
> what's happening.
> 
> Could this be used for some type of velocity or after-touch function?  I'm
> not familiar with this arrangement at all (I don't get a chance to dissect
> too many keyboards).  If anyone knows, please enlighten me!
> 
> I'm tickled pink with this keyboard, I'll post pictures of it on my web
> page
> if anyone else is interested in scoping it out in better detail than
> Electronic Goldmine provides.
> 
> Thanks for the bandwidth,
> Scott



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