Oz:
Oh my, I'm deeply offended.
Actually, I never recommended 4 car batteries, but it
can be done that way. Wire them in series, charge them
in parallel. (Did I forget to mention that I am a Certified
Electronics Technician?)
Phil has verified the voltage specs in a personal post.
<QUOTE>
Hey Ray- this is great information, but I have revisited the specs for this
switch...
http://www.cisco.com/univercd/cc/td/doc/product/lan/28201900/1900dc/dcpwrint
.htm#xtocid231323
To add to the mix, this requires: 39W, -40 to -60 VDC
Any ideas- could this be done with a polarity change ???
Thanks !!!
Phil
<END QUOTE>
This nails it down as destined for a telco supply. Yes, Phil, the polarity
switch is
all that is required. Marlin P Jones has one -48 VDC 1 amp (roughly 48
watts)
for $56, and one used -48 VDC 15 amps (roughly 750 watts) for $40.
A little history: telephone companies use/used batteries to supply their
power
to the lines. Whether it is +48 VDC or -48 VDC depends simply on whether
the
positive or negative supply line is attached to the ground (yes, to the
earth itself).
In modern supplies directly attached to the device both lines are attached,
and
neither line goes to ground, so a simple polarity switch is all that is
required.
-48 VDC is the nominal line voltage on a telephone system. This drops to
about
-20 VDC when someone picks up a receiver. The ringing voltage is about
90 Volts AC, which can easily damage sensitive DC based equipment, and
cause interference on adjacent data lines.
I am surprised at the wattage requirement. The 9 volt battery scheme
wouldn't
supply enough amps, and the 6 volt battery scheme would run the batteries
down pretty darn quick.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Oz
Sent: Monday, July 10, 2000 8:56 PM
To: [EMAIL PROTECTED]
Subject: Re: Running a DC powered Catalyst 1900 ???
Bzzzzzrt wrong answer HEH
The 48 volts is the DC power that the equipment uses My Portmaster box
needs 5 amps..
Some how I think the idea of dragging in 4 car batteries would test the
"wife to rack in kitchen quotient"
The 8 foot rack was a definite * what !!! are you out of your (expletive
deleted) mind.
4 car batteries would be cause to find myself impaled on less than small
kitchen knife.
Big time heh
"Somebody else said that it was 48 volts.
That's the line voltage on a telephone line, and
as we know, a telephone line does not carry a
lot of amps, so almost any 48 volt source would be
enough."
Oz
http://www.mcseco-op.com/helpfull_links.htm
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