Is there anyone outhere who has made up DIY modules using schematics
from the Moog Modular system or am I the only one? I started about eight years
ago and now have a modular 3C up and running (yes I am bragging..but
much toil, and headaches involved i.e.for instance casting control knobs
in resin, obtaining replica switches components and design work for front panel legends to name a few of dozens of problems to overcome) In fact
making up the electronics was the "fun"bit…I have just the high pass and
coupler to make up. My only failure is the double trigger delay unit…I cannot
get it working… If any one has made up any units etc I would like to here from you..
Do you have any pics of this?
Yes..or I will have in about 10 days or so when the final front panels are finished…I will post them on the net soon as they are done..
While I’ve never built a Moog from scratch, I can appreciate what you’ve done.
There’s a LOT to know that isn’t in the schematics. Even a few typos and factory changes not obvious.
No slam, but I’m curious why you went to the trouble of casting your own knobs?
The exact same knobs, from the original company, have been available new ever since Moog began.
Cloudhop, look forward to hearing and seeing more of your project.
Kevin, good to see you here.
Brian
I tried all over to get genuine Moog knobs but found the only supplier
was Analogue Systems of Cornwall which only had two designs and were
expensive…being a sculptor/caster I found I could make these up for less
than 5p each..however large inductors for the 914 were a different story
I had to make my own (yes..winding ECW onto ferite cores and they run at about
£15 each ..and there are about 30 in the circuit…
also ..yes there are a few things the schematics don’t make clear..but
with lots of trial and much error I have sorted all problems out…the only
2 major problems being the trigger delay and the multi mix units
the oscillators were several migraines 901-A and 901-B versions but they
sound truly superb! thanks for your interest
Very cool.
Obviously a labor of love. 
If your 901A/B’s have any tracking or ranging switching inaccuracies, give me a shout.
I’ve come up with a few tricks to get them to behave.
I take it that you must have some 901-A’s & B’s…at the moment i have
2 x 901-A’a and 4 x 901-B’s…I obtained 6 x CA19 diode clusters which
are pretty rare and so I can make another 901-A if i wish but I think I
will
be happy with 6 x Osc. system.
I have not made the keyboard circuit although I started one by ripping out
the inners of a Compact piano and using spring contacts but with my Kenton
CV controller I’ll stick to MIDI control ( one less huge headache regarding
tracking) I get about one and a half octaves of good tracking once the system has warmed up but it’s very unstable at times.
regards Paul
I don’t own any synths besides a Roland D-50, but I restore Moogs for a living.
(see here: http://www.moogmusic.com/service.php)
I sold off the last of my CA3019 diode arrays also.
They rarely go bad and I wasn’t replacing any, nor building things from scratch.
On the 901s, obviously make sure that transistors and caps are matched very closely between the modules. Several resistors in logical places should also be matched. There will be some adjustment necessary anyways via fixed resistor substitution for equal pulse width, waveform offsets and the like anyways.
Moog used precision matched caps to acheive range switching in the 901B’s. Matching caps is often more difficult than matching resistors, especially for pf values and differences. Moog often had 2 or 3 caps paralleled to achieve the correct total values and even then, it could be off in short order. It helps to buy large lots of caps and from different sources. Easier to match when there’s many varied values.
The less caps you use per interval the better too as the variances, especially over time, can be multiplied. Ideally, one cap per octave is best, but you likely won’t achieve that, especially with the linear values chosen.
But here’s a trick. You can trim the octaves (once you’ve done your best cap matching possible) by using resistors in parallel to the caps. Standard R/C theory. You will need very high value resistors in the 5 to 30 meg range (often around 12-20 megs), but via this method, it’s much easier to land on the intended octave intervals. I recommend tuning via a precision audio reference and not via a frequency counter. I use my D-50 (often hooked to a good MIDI to CV converter) to rely on a computer generated, non varying intervals. (obviously the effects are turned off in the Roland.)
Thanks for your ideas…I have taken great care with all the components
using only the top speck particulaly for the Osc’s etc…I may tweek them a little later in time but at the moment they seem fine enough..I hope to have a total of 6 x 901B’s in the cab…I have photo’s of the my DIY 3C which I should send but not sure how to ZIP them into e-mail..I’ll have a go anyhow…
best wishes
Paul
I’m really looking forward to see the pics of your DIY 3C project! 
How many hours have you put into this project?
Hi
Thanks for your interest…as to how many hours well it must run into hundreds…I started the project in 1995 and am just about on the last
leg however I had a break of three years when I did no work on it at all..
you may be suprised to know that I really did not know much about electronics at all when I started..i have picked things up as I went but even now I would not call myself informed in the field of electronics..i got the
modules working mostly thru trial and error so if I did it anybody can.
I am trying to get my pictures into e-mail but am having trouble so I will
post a query on the forum asking for help…
regards