[sdiy] Noisy transformers and faraday cages

[Altitude]

There were really no big issues.  It was really my first "real" project
where I only started with PCB's (everything else I have done were kits or
semi kits)so it really was a very good learning experience on all fronts.
The most time consuming thing was sourcing all the parts.  I ended up buy
most of the rarer IC's from Nikko Electronics in the UK which have just
about everything at very good prices even with worldwide shipping. An other
mistake I made was not checking the pitch of all the non-polar caps.  I used
Wima polyester caps which worked out great but the discount supplier
(Futurlec) I used had lots of different values but didn't have drawings or
spec sheets for the parts so I ended up with a hodge podge of 5,7, 10mm
spaced parts so there was a lot of lead bending which was pretty time
consuming.  Learning why it is good to use organic (water soluble) flux
based solder was probably the most valueble lesson though since cleaning the
rosin based stuff off of two large boards with so many components is not
something I ever plan to repeat.  Finally, there were some minor errata in
the documentation and files (both the schemes and supporting files like the
FPDs) which were corrected and gone over in the Yahoo group.  If you have
not already, read through as much of group as possible since there is a lot
of good info there.  

I used my 9090 as a testbed for processess that I intend to use on future
projects so mine took about a year to finish completely.  Most of that time
was actually spent experimenting with various paints and working on the
case.  I used Schaeffer to do all the machining (which ended up being around
~$90 for all three panels) and then did all the graphics myself using the
injet based lasertran.  This worked out BEAUTIFULY and I am thrilled with
the results (I'll post pics in the yahoo group once it's put back
toghether).  I cant stress how great and cheap this stuff is.  You literally
have to examine the panels up close (and I mean close) to be able to tell it
is not silk screened.  The paper cost (11"x17") was $3.50 (USD) per sheet,
printing 2 sheets (3 labels per sheet) at kinkos on their wonderful color
lasers was $3.00, Krylon matte clear enamal $2.75 :)).  Which is less than
having 9090 ANALOGUE DRUM SYNTHESISER engraved at schaeffer and I can go to
town with full color graphics.

As far as the sound and overall design, it is as perfect as it can be.
Trevor really outdid himself and deserves volumes of praise.  I really could
not be happier, both with the outcome and the fact that it is FINALLY done
:P

Cheers,
R-
-----Original Message-----
From: Brett Maddaford [mailto:Brett.Maddaford at mailus.com.au] 
Sent: Thursday, May 10, 2007 7:51 PM
To: Altitude; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Noisy transformers and faraday cages

Heya Raph

Well done, mines still being worked on and has been for over 18
months...other projects keep getting in the way.
So did you find any big issues and are you impressed with the outcome ;)

Cheers
Brett

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of John Mahoney
Sent: Friday, 11 May 2007 03:13
To: Altitude; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Noisy transformers and faraday cages

At 12:20 PM 5/10/2007, Altitude wrote:

>I am wrapping up my 9090 drum synth and am wondering what would be the 
>best way to provide some shielding to my fairly electrically noisy 
>transformer (Hammond 30V CT @ 500mA).  The way the outputs are set up 
>is that there is no real way to avoid running audio leads by the 
>transformer and the noise goes down when the I move the leads away (the 
>primary side is the worse)
and
>I am using shielded audio cable.  Would putting up a mesh or steel box 
>around the transformer help in reigning in the noise? Any other 
>recommendations?
>
>Cheers,
>Raph


Mu metal?
--
john


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