MOTM

I'm starting to worry about current draw of some digital-based MOTM-500 series modules.

I want to use nice LED alphanumeric displays for some of the modules. LCD needs a backlight, and
that also sucks power. How much power? The uP(s) + displays are at about 300ma to 400ma.

Of course, I can add a +5V regulator to the +15V line, but that sucks all your +15V current.

So, what I am thinking is using a "line lump" +5V switcher. These have "universal inputs": they
will work anywhere in the world without a jumper. The plug is a standard-sized 'barrel' female. I
would have a 1U panel made up with

a) panel-mounted male connector
b) power LED
c) auto-power switch: the +15V turns on the +5V
d) a new distribution board with 3-pin MTA connectors

These little supplies can pump out 3A no problem. This also keeps the "noisy digital" supply from
getting back into the "quiet" +-15V lines (there will still be filtering).

The cost for everything would be $89 or $99. One of these could power 8 or so 500 Series, and
they make even bigger ones (like 5A out).

I'm assuming the isolation is such that the +-15V from MOTM-900s would still be used to power up
the "analog" parts of the 500 Series. Also, it may be possible to take the +5V input and on the
module, convert to +-15V just for *that* module's use. The reason is that the current for +-15V
is usually on the order of 20ma. Another thing to consider is that the 500 Series modules are not
"clean" like say a VCO or VCA is. If there is some local power supply "grunge", that DOES NOT
find it's way back into the "clean" supply, you will never "know" it was there in the first place
(how 'clean' does a fuzz box need to be?).

There is 1 more solution: a 3U wide MOTM-950 Supply. It's got all 3 voltages BUT the +-15V is
lower current: 400ma instead of 800ma. This is used to power 500 Series ONLY. The 500 Series
would use a 6-conductor MTA-156. The +5V is rated at 2A. This could power between 5 and 8 500
Series.

Thoughts??!?

Paul S.

I like the separate power supply with 3 voltages, with a different
connector.  That is what I am planning, going linear all the way.  And, that
would me it easiest for the buy-and-plug guys that don't build.  And, make
us a PCB like the 960 with the MTA-156-6 connectors.  If someone really
wants to cheap out (even temporarily) with a 5 volt switcher, they can
connect the +/- 15 from their linear supply to the 960-6 PCB and connect the
5 volts from a switcher.

The part that I don't like the sound of is powering the whole thing from a 5
volt switcher stepping up on the PCB when you need +/-15.  And, I don't like
the sound of using a +5 volt regulator on the 500 series and using up the
+15 leg too fast going the other way.

I think the 3 voltage supply approach will be easiest too when we have a
sequencer.  Need lots of +5 and a little of the other. Maybe the new MOTM
supply could be right for "a few 500 series" or "sequencer only" power
supply.  Plus it makes it easy to stay with the single Neutrik external
power connector as that standard develops.  If you plug in the wrong supply
it either:
a - ignores the 5 volts as not needed.
b - doesn't work because there is no 5 volts supply, but nothing is damaged.

Plus, you might have a market out there for 500 series guys that won't /
haven't bought any of your other stuff.  They will not like to cabbage two
supplies just for their 500 stuff. Or, maybe they have one or two of your
+/-15 modules and don't want to have two supplies.

All together a separate 3 voltage supply makes the most sense.  I like the
idea of the MTA-156-6.  Gotta have a distribution PCB too though for us
cabinet guys.

And last but not least, it makes it easier for the guys that like to mix in
a little dot com stuff.  You may not see that as an advantage.   But, there
is no MOTM sequencer in the near term (that we have heard about). The dot
com sequencer might be attractive to some MOTMers.  I think the ability to
mix and match for those that choose too is actually good for both you and
Roger (saying that after selling my only dot com modules).  It would be nice
to stay 100% with MOTM power supplies.

That's my $.02
Larry

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

From: Paul Schreiber <synth1@...>

> I want to use nice LED alphanumeric displays for some of the modules. LCD
needs a backlight, and
> that also sucks power.

i prefer LED over LCD if there is a choice (lcds are so 80's !)

> So, what I am thinking is using a "line lump" +5V switcher. These have
"universal inputs": they
> will work anywhere in the world without a jumper. The plug is a
standard-sized 'barrel' female. I
> would have a 1U panel made up with

i don't like the of the wallwart / line lump - it seems to let down what is
currently an elegant solution
if this idea were transferred into in kind of mini 900 series PSU delivering
+5v i'm sure many people would find this more paleteable - subject to cost
of course. i like the 950 superpsu but think the mini supply would suit my
needs at least until i got a pile of 500 series and a dotcom sequencer
almost filling one cabinet

cheers
paul b

I think a totally seperate power supply for all three voltages is 
the way to go.  I don't like the idea of getting digital noise on 
the supply lines for the analog modules, and I don't like 
wallwarts.  On the subject of LEDs vs. LCDs, I have no particular 
preference as long as they're all the same.  I have a really cheap 
LCD handheld oscilloscope that I was thinking of trying to adapt to 
a MOTM module as well.

I think a totally seperate power supply for all three voltages is 
the way to go.  I don't like the idea of getting digital noise on 
the supply lines for the analog modules, and I don't like 
wallwarts.  On the subject of LEDs vs. LCDs, I have no particular 
preference as long as they're all the same.  I have a really cheap 
LCD handheld oscilloscope that I was thinking of trying to adapt to 
a MOTM module as well.

> i prefer LED over LCD if there is a choice (lcds are so 80's !)

And LEDs are so 70s... How 'bout Nixie tubes? They're so, uh... 50s? 60s?
I'm not sure when those were the numeric output device of choice--I just
remember seeing them in some ancient machine many years ago.

--Adam

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

From: "Adam Schabtach" <adam@...>
> And LEDs are so 70s... How 'bout Nixie tubes? They're so, uh... 50s? 60s?
> I'm not sure when those were the numeric output device of choice--I just
> remember seeing them in some ancient machine many years ago.

if only paul were to offer nixie tubes !!!
i've an old marconi frequency counter, the only reason i've kept it is for
the nixie tubes
there's a chap in the states that sells the parts for a nixie tube clock,
but it's a little beyond my experience at the moment...

cheers
paul b

At 11:00 PM -0500 09/01/02, Paul Schreiber wrote:
>
>I'm starting to worry about current draw of some digital-based MOTM-500
>series modules.

Cool, that's means you are working on them :)

>I want to use nice LED alphanumeric displays for some of the modules. LCD
>needs a backlight, and that also sucks power. How much power? The uP(s) +
>>displays are at about 300ma to 400ma.

I agree, LED is way better than LCD.

>Of course, I can add a +5V regulator to the +15V line, but that sucks all
>your +15V current.

As I'm sure you already know, there are voltage inverting switching
regulators, but running off the -15V doesn't sound like a good idea either
(not to mention the cost and complexity added to each module).

>So, what I am thinking is using a "line lump" +5V switcher. These have
>"universal inputs": they will work anywhere in the world without a jumper.
>>The plug is a standard-sized 'barrel' female.

That sounds like a good idea.

>I would have a 1U panel made up with
>
>a) panel-mounted male connector
>b) power LED
>c) auto-power switch: the +15V turns on the +5V
>d) a new distribution board with 3-pin MTA connectors

Would all that be necessary??  I don't see the advantage of having a panel
if the switch is auto.  Nor do I see the advantage of having a power LED if
these modules have LED displays.

While I realize it's the wrong way to distribute +-15, perhaps a
daisy-chain system would work for +5V.  The back of each digital 500 module
could have two "line lump" jacks wired in parallel.

Then people could plug their linear supply and their +5 switcher into the
same power strip, and use that to turn everything on and off.

Even if an auto-power switch is necessary, it still does not require a
panel.  It could be mounted on the distribution board behind the scenes,
which, imho, would be much more elegant.

>Also, it may be possible to take the +5V input and on the
>module, convert to +-15V just for *that* module's use. The reason is that
>the current for +-15V is usually on the order of 20ma. Another thing to
>>consider is that the 500 Series modules are not
>"clean" like say a VCO or VCA is. If there is some local power supply
>"grunge", that DOES NOT find it's way back into the "clean" supply, you
>>will never "know" it was there in the first place
>(how 'clean' does a fuzz box need to be?).

(That's a very difficult question to answer.  Imho, there is a huge
difference between distortion, and hum and noise.)

>There is 1 more solution: a 3U wide MOTM-950 Supply. It's got all 3
>voltages BUT the +-15V is lower current: 400ma instead of 800ma. This is
>>used to power 500 Series ONLY. The 500 Series would use a 6-conductor
>>MTA-156. The +5V is rated at 2A. This could power between 5 and 8 500
>Series.

I guess that would be OK for someone who wants an all-500 system, but even
they might want to add some non-500 modules as well -- perhaps an LFO or a
couple of envelopes as mod sources.

Also, the 500 modules might bring new people into the system.  Let's say
people who don't have any MOTM buy 500's in order to add new and different
modules to their setup.  Then when they realize for themselves all the
advantages that are hard to convey through a website -- ergonomics,
precision, build quality, convenience of 1/4" jacks, etc. -- they might
want to buy more MOTM.  However, they might be less likely to start adding
non-500 modules if they have to buy another power supply.

At 11:00 PM -0500 1/9/02, Paul Schreiber wrote:
>c) auto-power switch: the +15V turns on the +5V

What happens if there is no +5V power when the 15V turns on, does the 
module get damaged at all?


>There is 1 more solution: a 3U wide MOTM-950 Supply. It's got all 3 
>voltages BUT the +-15V is
>lower current: 400ma instead of 800ma. This is used to power 500 
>Series ONLY. The 500 Series
>would use a 6-conductor MTA-156. The +5V is rated at 2A. This could 
>power between 5 and 8 500
>Series.
>
>Thoughts??!?

How about a new larger current full size power supply that could 
power the same number of both old and/or new modules.

Maybe it could have normal connectors for +- 15V to old and new 
modules, with a separate 5V connector/wiring scheme for the new 
modules.

This way people with existing power supplies could add the walwart 
solution to their system, and people buying new supplies could just 
buy the new supply and not have to deal with a messy power system 
using two separate power cables/switches/etc. per cabinet.

And while you are designing a new supply, could you please add remote 
on/off capability, so that we could use a non-powered front panel 
switch if we want to. The remote part of the circuit could be 
jumpered so that it could work as either a normal rear panel or 
remote/front panel switched system. It could also have power status 
lights on the front panel for the DC power rails/AC power/standby/etc.


Simon
Canberra
AUSTRALIA

I am a new MOTM user, putting together MOTM/Blacet/Oakley modules 
into a large cabinet or two. I will want to use some 500 series 
modules in the same cabinet as the older modules.

I don't want to use multiple power supplies in my cabinet. I don't 
want to have a smaller number of modules in the cabinet because the 
modules draw too much power for the existing power supply.

New MOTM users wanting to use both old/new modules will/do want a 
single supply in their cabinet. Not some botched-together solution 
using multiple power supplies per cabinet, that is a really 
messy/unprofessional solution in my opinion.

Existing MOTM users want to add 5V to their existing power supply to 
support some new modules in their system.

Please give us a nice clean/single power supply solution to power 
cabinets containing both old and new modules. And, an upgrade 
solution for owners of the older power supply to add 5V to their 
supply.

You would be turning away new customers if they had to buy two 
separate supplies for a single cabinet. The idea certainly doesn't 
meet the high level of design quality that I would expect in a MOTM 
product.

It seems that you are compromising by trying to fit the new power 
supply into the same sheet metal to reduce costs, or to keep existing 
users happy.

You should take this opportunity to make a new more powerful power 
supply to support similar cabinet sizes to the old power supply did, 
using a mix of old and new modules or just all new modules.

You could sell the new power supply to anyone wanting to use any new 
modules, the old power supply to people who only want to use old 
modules, and the 5V upgrade to existing users that want to add some 
new modules to their existing system.

Simon
Canberra
AUSTRALIA

>There is 1 more solution: a 3U wide MOTM-950 Supply. It's got all 3 
>voltages BUT the +-15V is
>lower current: 400ma instead of 800ma. This is used to power 500 
>Series ONLY. The 500 Series
>would use a 6-conductor MTA-156. The +5V is rated at 2A. This could 
>power between 5 and 8 500
>Series.

Smaller power supply for only 500 series modules is a bad idea!

This is supposed to be a modular system, I want to mix old and new 
modules in the same cabinet, and I don't want multiple supplies in a 
single cabinet.


And, front panel power switching is important to me, it really makes 
the system seem more 'professional', better quality, etc. This is 
speaking from experience with a Roland System 700 which has front 
panel switching, I really don't want to reach around behind a large 
cabinet to turn it on and off, it might be OK for a keyboard, but not 
a large modular system. I have a number of large synth cabinets 
stacked right next to each other, and ontop of each other, there 
simply isn't room to leave space to reach around behind large 
cabinets.


Simon
Canberra
AUSTRALIA