Archive of the former Yahoo!Groups mailing list: 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.