[sdiy] Hammond Aurora Keybeds

[drheqx]

Yes sir, and they are. They're not the multi-bus wire type but they are
direct metal strip on wire and they're going to be oxidized to a certain
degree.

On Fri, May 16, 2025 at 6:17 AM <rburnett at richieburnett.co.uk> wrote:

> You can also do whatever flavour of switch de-bouncing that you want in
> software, if the key contacts are a bit old and scratchy!
>
> -Richie,
>
>
>
> On 2025-05-16 03:54, Ben Bradley via Synth-diy wrote:
> > "Each key closes a switch to a common bus."
> >
> > There's a couple things you need to make a "true analog" mono
> > keyboard. First is a constant current source to drive the resistor
> > divider, so that when more than one key is pressed the voltage remains
> > that of the lowest or highest key (unless you WANT a weird off-pitch
> > note effect when pressing more than one key). The other is  a separate
> > switch at every key that closes AFTER the key that gives the pitch
> > voltage as the key goes down, so that the proper voltage is sampled
> > and kept when the key is released. This is also the gate/trigger
> > output. Presuming there are several common busses, you need to bend
> > the contacts on each key to make sure these close in proper sequence.
> >
> > I don't see a problem of being off-pitch with a resistive divider, as
> > 1 percent resistors are cheap thesedays, whereas 1970s keyboards may
> > have used 5, 10 or even 20 percent tolerance resistors.
> >
> > But still, I'd as soon make a digital circuit to scan/read all the
> > separate inputs, one for each key, scan it into a buffer with a
> > microcontroller and do the highest/lowest/latest keydown logic in
> > software and the usual DAC for control voltage output.
> >
> > On Wed, 14 May 2025 at 22:54, drheqx via Synth-diy
> > <synth-diy at synth-diy.org> wrote:
> >>
> >> Hi all,
> >>
> >> I have the keybeds and draw bars etc. from a Hammond Aurora organ.
> >>
> >> These are not matrix type keybeds. Each key closes a switch to a
> >> common bus.
> >>
> >> Is this a good time for me to consider doing a volt
> >> /octave keyboard controller?
> >>
> >> I definitely don't want to midify these. That would be a waste.   I
> >> was considering building a voice per key synth because i love these
> >> key beds and it would be so unique, but I'm short on time like so many
> >> of us.
> >>
> >> Anyone know of a good kit to make a 1v/ oct controller, maybe with
> >> some added features.
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