Be careful about trying to use an Astron RS-35M as a
battery charger. Several years ago I had used the one
I have here in that fashion and ended up shorting the
crowbar circuit's SCR. I never fully figured out
exactly what happened but suspect I got into trouble
by turning off the power supply before disconnecting
it from the battery. This is the exact scenario that
you would have with the "bridge" battery on the power
supplu output as you propose. Also consider that
Astron does have versions of their power supplies
specifically designed for use with batteries. The
other thing I seen done is to put a series diode in
the + lead to the battery.
On the other hand the UPS wouldn't really need to be
that big for what you are trying to do. Something on
the order of 500VA should handle a brief power outage
period with a 25A load on the supply. This based on
25A x 20V, as I recall the pre regulator/pass
transistor voltage of the Astron supplies is about
20V, (note that this quick and dirty estimate ignores
transformer efficiency). If you use a max load case
you'd be looking at acquiring a UPS required to handle
700VA (35A x 20V). I haven't done this yet myself so I
can't speak about any UPS RFI generation issues,
perhaps someone else here on the TT mail list has some
more experience about that potential problem?
It is for sure that the filter caps will not hold up
for more than a few tenths of second under a light
load, and hardly at all under a significant load. So
if you have numerous glitches in your AC service the
filter caps will do little to nothing to help you.
Duane
N9DG
--- Bill Tippett <btippett@alum.mit.edu> wrote:
> I've ordered an Orion and for the first time will
> be
> using an outboard DC supply (a used Astron RS-35M
> is on the way). I often get short power glitches
> since I am
> in a rural location and am concerned about getting
> resets
> on Orion since I understand it takes awhile to
> reboot (how
> long?) I'm thinking of getting a small battery
> (motorcycle)
> to place between the RS-35M and Orion. This would
> stay
> fully charged and might help prevent unwanted resets
> by
> brief power glitches.
>
> Has anyone ever done anything like this? Is it
> even
> necessary or is there enough residual energy in the
> PS
> filter caps that brief interruptions (typically <10
> sec) are not
> a problem? I don't really want to buy a UPS large
> enough
> to power Orion but is there a simpler solution?
>
> 73, Bill W4ZV
__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com
|