From: massoud@chemteca.sdsu.edu (Massoud Ajami)
Subject: Re: Resetting a computer by phone
Keywords: reset, computer, phone, remote
Organization: San Diego State University
Distribution: usa
Date: Sat, 22 Aug 1992 18:41:32 GMT

In article <1992Aug21.033107.9085@nosc.mil> gag@nosc.mil (Gary A. Gilbreath) writes:

>Has anyone seen a product that will allow you to remotely reset a
>computer by using a phone?  I often use a program that allows me
>to remotely access my computer from home, but sometimes the computer
>hangs and I have no way of restarting it.

>I would prefer to only have to use one phone line.  However, if there
>is some very simple/cheap device that can do the job from a second line
>that might be OK (it would have to be pretty cheap or easy to build).

>The only way I can think to get a single phone line to work would
>be to monitor the serial line between the computer and the modem.  The
>device would look for a specific character sequence (possibly including
>BREAK and/or critical timing to avoid inadvertently resetting the
>computer with arbitrary binary data), and then either close a relay/
>solid-state switch/FET to toggle the reset line, or actually cycle
>the power to the computer using a S-S switch or relay.

>I think this could be done without too much trouble with a simple
>microcontroller and a few external components, but I wondered if
>someone knew of a device I could just go out and buy.

>Thanks,

>Gary Gilbreath, NCCOSC, RDT&E Division, San Diego, CA
>Internet: gag@manta.nosc.mil
>uucp: {ihnp4,akgua,decvax,dcdwest,ucbvax}!sdcsvax!nosc!gag

        ------------------------------------------------------------|
       |                                                            |
  tip -|-ccc---rrr---                                               |
                     |                                              |
                    / \                                             r  600
                  /     \                                           r  ohm
                /  FWR    \             Vref     |\                 r
               |\ ---->   /------         o------|- \               |
               |  \     /        |               |    \             |
               |    \ /          r               |    /-----|       |
               |     |           |        |------|+ /       |       |      r
  ring -|------|------           r        |      |/         |       |    | e
        |      |                 r<-------|                 r    |o-| |o_| s
        |      |                 r        c                 l====|====|    e
        |      |                 |        c                 y    |o-  |o-| t
        |      |                 |        |                 |       |    |
        |      |-----------------|--------|-----------------|       |
        |-----------------------------------------------------------|
               
This little gadget may do the job. By adjusting the r, or Vref, you can 
trigger the relay based on the number of rings that you recieve. One set of 
contact is used for reseting the computer, and the other set is to act as 
pick up action. If computer is hung, modem would not answers, so, say you 
let it ring 10 times (while modem answers less than that), you hear hand set 
pick up, hang up, then dial again, and this time modem answers. Of course if 
you load your comm. program bu autoexec.bat. Remember, the ring voltage can 
be up to 90 volts, don't zap your compatator!


Peace and Prosperity!
  ---==< 110 >==---
Newsgroups: comp.sys.ibm.pc.hardware