[23049] in North American Network Operators' Group
Re: Maintenance modems and power failures
daemon@ATHENA.MIT.EDU (Bryan Bradsby)
Fri Feb 12 10:02:22 1999
Date: Fri, 12 Feb 1999 08:52:31 -0600 (CST)
From: Bryan Bradsby <Bryan.Bradsby@capnet.state.tx.us>
To: nanog@merit.edu
In-Reply-To: <4.1.19990211141936.020308c0@pgemail.pgexch.com>
At 01:14 AM 2/12/99 -0500, Joseph Lapolito wrote:
> We have been using a DC powered 28.8 modem made by
> a company called WTI.
> It is basically a USR modem ripped open put into a rack mount
> chassis and converted to take a .25amp DC feed.
Or you could find someone in your organization handy with a soldering
iron and follow this basic recipe -
Cut the transformer off your modem power cord.
Connect reliable -48 VDC to a fuse, resistor and zener diode.
This is not rocket science, but observe proper voltage and power rating
on the zener, wattage and value for the resistor, and polarity on the DC
feed into the modem, and ground isolation on the selected modem.
Or you could battery backup the main power to the building, with automatic
switch over to redundant diesels. Works nice at HQ, a little pricy for
remote sites. Your choice.
-bryan
CapNet / Tex-an Network
Texas Government and Educational Network NOC: 512-475-2432
a facility based Network Service Provider fax: 512-463-3456
