[sdiy] Hammond Aurora Keybeds

[Mike Bryant]

Are you sure they'll be oxidised ?  The ones I used back in 70s all had gold plated wires and busses so they couldn't oxidise.  MIght be a bit of crap on them but never anything worse.

________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of drheqx via Synth-diy <synth-diy at synth-diy.org>
Sent: 16 May 2025 13:07
To: rburnett at richieburnett.co.uk <rburnett at richieburnett.co.uk>
Cc: synth-diy mailing list <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Hammond Aurora Keybeds

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<mailto: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<mailto: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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