[sdiy] Minimoog clone

[Bryce Lanham]

On 7/10/10, David Griffith <dgriffi at cs.csubak.edu> wrote:
> On Sat, 10 Jul 2010, Bryce Lanham wrote:
>
>
> > Hi David,
> >
> > I've been working on a miniclone on and off for 5 years, delayed
> > mostly because of school, then college. I am actually in the process
> > of finishing at this very moment.
> >
> > I went the more authentic route, laying boards out in Eagle following
> > pictures of the original layouts, with someone on-list giving me the
> > dimensions. Tracked down the original AMP Duo-Tyne connectors and
> > pins, actual honest-to-god E402's, and stumbled across a cache of
> > Allen-Bradley Type J potentiometers. I may have found a solution for
> > the unobtanium UID rocker switches; I'll know more by next weekend.
> >
>
>  I have half a mind to rework the layout to allow for different part
> footprints.  For instance, a trimpot is a trimpot.
Yep, I changed a few things. Wirewound trimmers are hard to find, and
I didn't want to use them anyway. I also changed the footprint for the
dual-jfets to DIP-8 for when I get some DIP-8 LS3954s from Linear
Integrated Systems.
> For the panel pots, is
> there anything wrong with using Alpha pots?

Not really, I just happened to get a bunch of Type J pots, and figured
I  might as well use them. They are a bit stiffer than the Alphas I
have around.  One issue is the modulation pot; it needs to go as close
to 0 ohms as possible:
http://www.moogmusic.com/forum/viewtopic.php?p=19227&sid=dbb9237b6d774fa4c1720c32ab8eb5fa
The other is that the Glide pot used a weird taper:
http://bobmoog.info/forum/viewtopic.php?f=1&t=5889, which could
probaly be fixed with some math and the application of a tapering
resistor.
>
>
> > My site, which needs to be updated badly, is here:
> > http://brycelanham.com/mediawi​ki/index.php/Minimoog_Clone. I can put
> > the Eagle files up if you want. The parts info is more current on
> > Joe's site, I missed the 2n4058's at MCM and my supplier for rev-log
> > potentiometers is no longer around. Pictures are here:
> > http://www.brycelanham.com/blo​g/wpg2?g2_itemId=21
> >
>
>  I've been warned about errors in the schematics.  How much of a problem was
> that for you?
I can't remember if i caught any  in the board layout process; that
was a long time ago. I found one of them the other day, when I finally
tried the headphone amp for the first time.
>
>
> > I have the power supply board working on my desk, and am trying to
> > rebuild my oscillator board harness to check if that board still
> > works.
> >
> > I have a CAD model of the mini, thanks to list member Tim Parkhurst,
> > but I'm not that good at using AutoCAD, and the model is missing all
> > of the inner front-panel mounting screw and potentiometer-stop holes.
> > Anyone have pictures of a Mini with its' front panel removed? I
> > finally gained access to a metal shear and break, and figured I might
> > as well go full-out and completely copy the original case.
> >
>
>  When you do that, I'd appreciate it if you could make me a case too.
I may be up to it, we'll have to see how my attempt goes first. I wish
I could find someone in the Chicago area that owned a Minimoog and
would allow me to take detailed measurements.

>
>
> > The keyboard is also giving me a bit of trouble. I have an old organ I
> > could cannibalize, but I 'm also considering cannibilizing a cheap
> > midi keyboard and using a microcontroller to interface it to the
> > original keyboard circuitry.
> >
>
>  I took apart a Roland pc200mk2 to clean out cat pee and found what I guess
> is a Fatar keybed.  As a quick and sloppy look, I think a metal bar could be
> laid across the PCB to get a bussed wiring scheme.
>
>  --
>  David Griffith
>  dgriffi at cs.csubak.edu