MOTM

Hi all.

I have been lurking about the list for a time and am enjoying every
minute of it. I am just beginning my thought process for a modular for
the studio (MOTM of course), and wanted to ask about the Power One Power
Supplies. I don't recall who had mentioned it on the list, but this was
an alternative to the 900 PS offering a higher load capacity. Perhaps I
have delusions of grandeur about how big of a synth I can build, but I
wanted to start here.

Has anyone posted a schematic for this power supply? Is it a regulated
supply? Any tips and info would be appreciated. Yahoo (yuck) search of
the archives did not help much.

Thanks, Scott

In a message dated 4/9/01 3:41:56 PM, esresource@... writes:

<< I am just beginning my thought process for a modular for the studio (MOTM 
of course), and wanted to ask about the Power One Power Supplies. >>

The Power One power supplies are generically referred to as open-frame linear 
power supplies.  They are power supply circuit boards typically mounted to a 
combination mounting frame/heatsink.  Since they are "open-frame" they need 
to be enclosed somehow.  This is what is used in the MOTM-900, although it is 
packaged nicely with a front panel and such.  Go the MOTM route if you don't 
want to deal with the mounting issues or if you feel uncomfortable wiring 
120VAC devices.  This is the best route to go unless, as some people have 
mentioned, you need a huge power supply.

There are many places where you can buy these supplies new (Digikey, Newark, 
etc.) but I have found them surplus.  You are looking for a high-current +/- 
15VDC unit.  I bought mine from C&H Sales:

http://aaaim.com/CandH/

The +/-15VDC 1.5A model is Stock #PS9603 (Power One CP131A which also has 
5VDC @ 8A), the +/-15VDC 0.8A model is Stock #PS9910 (Power One HAA15-550).

For REALLY huge systems they also have some supplies with +/- 15VDC 10A 
outputs.  Great if you're into overkill.

Detailed info can be obtained from Power-One:

http://www.power-one.com/

By the way, people seem confused about low-voltage wiring.  Ever wire up a 
car?  Think low-voltage and high current when doing DC power distribution for 
a large MOTM system.  Sure, the supply may only have an 18 gauge 120VAC 
cable, but at 15VDC that 1.5 amps needs a bit of copper if it is travelling 
far.  Beefy is better!  Nothing ridiculous, but 14 or 12 gauge isn't out of 
the question.  Not to each module, but from the power supply to the power 
distribution board.

Ivan

----- Original Message -----

From: Scott Evans, Gen Mgr <esresource@...>
I have been lurking about the list for a time and am enjoying every
minute of it. I am just beginning my thought process for a modular for
the studio (MOTM of course), and wanted to ask about the Power
One Power Supplies. I don't recall who had mentioned it on the list,
but this was an alternative to the 900 PS offering a higher load capacity.
Perhaps I have delusions of grandeur about how big of a synth I can
build, but I wanted to start here.
--------
Scott, the power supply in the MOTM-900 is a Power-One supply.  However,
Paul has added all the extras you need, like a switch, power connection,
front panel, PCB to plug in your MOTM modules, etc.  That makes it simple -
plug and play.  If you buy the Power One supplies separately, you have to
supply that support suff yourself.  Of course, you can and should get the
power disctribution PCBs from Paul if you choose that method.  If you are
rack mounting your supply, you might as well buy what Paul sells ready to
go.  If you are doing a wood case and plan custom wiring, you can buy a
Power One directly and fix up the AC, power switch and all just the way you
want it.  You will need to add appropriate fuse protection.

The Power One supplies are available from all the regular mail order
sources.  However, check the surplus mags first if you want to go that way.
I found 1.5 amp supplies that were fitted to a bracket, and then not used
for $19.95.   Then I found brand new 5 amp supplies (yep 5 AMP) for $24.95.
That is just a fraction of the new price. Not junk, the good stuff at blow
out prices.  But, surplus deals come and go.  So, you have to buy what you
want now.  Don't expect to always be able to buy at that price.  And, if you
go that route, don't forget you have overhead wiring to do on your own.

----------
> Has anyone posted a schematic for this power supply?


You have to be into self punishment to build a power supply.  You can buy
good ones so cheap.  Of course, you need to know what you are buying.  You
want a nice linear supply, not some cheap switching POS.

Try
www.mpja.com
www.mcmelectronics.com
for potential surplus deals.

Larry H

--- In motm@y..., "J. Larry Hendry" <jlarryh@i...> wrote:
> Scott, the power supply in the MOTM-900 is a Power-One supply.  
> However, Paul has added all the extras you need, like a switch,
> power connection, front panel, PCB to plug in your MOTM modules,
> etc.  That makes it simple - plug and play.  If you buy the Power
> One supplies separately, you have to supply that support stuff
> yourself.  Of course, you can and should get the power
> disctribution PCBs from Paul if you choose that method.  If you 
> are rack mounting your supply, you might as well buy what Paul
> sells ready to go.  If you are doing a wood case and plan custom
> wiring, you can buy a Power One directly and fix up the AC, power
> switch and all just the way you want it.  You will need to add
> appropriate fuse protection.

I've bought a couple Power One supplies to use with my other modulars 
(1.5A model for the one with tons of LED's), and had no problem 
wiring up the switch & FUSED (can't hurt to emphasize this - I HAVE 
blown one through stupidity ... see below) cord receptacle.  They've 
worked great.  Unfortunately, I haven't built enclosures for them 
(OSHA would probably haul my ass off to jail in a heartbeat), so I 
always have to warn people - DON'T stick your hand in the back of the 
modular!

Quick question, though (especially since Larry is the high voltage 
expert) - what's the deal w/stranded vs. solid wire?  I've been using 
14ga solid copper wire for the main (800mA or 1.5A) DC out, but 
(IIRC) Larry recommends stranded.  What's the reason for this?  (And, 
do I risk screwing things up by using solid?)  (And, for that matter, 
why is stranded used for all audio applications, from microphone 
level to power amp speaker level?)

Thanks,

    -Doug
     ceres@...

> (And, for that matter, 
> why is stranded used for all audio applications, from microphone 
> level to power amp speaker level?)

i always thought that this was just an ease-of-use thing.  at least 
that's why i've always used stranded.  especially with jack wiring, 
you never know when you're going to have to shove things around to 
fit all that stuff in the case.

alex

In a message dated 4/9/01 5:18:24 PM, ceres@... writes:

<< And, for that matter, 
why is stranded used for all audio applications, from microphone 
level to power amp speaker level? >>

FLEXIBILITY

Solid is great, but rarely practical.  Stranding is for flexibility.  Any 
other effects of stranded versus solid only occur at radio frequencies and 
above (sorry to the hi-fi tweeks out there).  Yes, solid wire works GREAT for 
speakers.  Just difficult to use.

Ivan

Scott