home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Magnum One
/
Magnum One (Mid-American Digital) (Disc Manufacturing).iso
/
d2
/
rebooter.arc
/
REBOOTER.TXT
< prev
Wrap
Text File
|
1989-06-19
|
8KB
|
200 lines
An Automatic Re-Booter for your Board
by Matthew Lewis
Sysop of Media Shack PCBoard
Toronto, Ontario, Canada
(416) 699-1846 ■ 300-2400 bps
Background:
This came about because of a couple of events that for
some reason didn't successfully complete, and the board
failed to reload, leaving my board down for most of the
day until I retured home from work.
I originally connected a telephone answering machine to
the board's phone line, and set it to answer on the
fourth ring. As the board normally answers on the first
or second ring, under normal conditions, the answering
macnine would do nothing, but if the board failed to
answer the phone, the machine would answer on the fourth
ring, play a tape to the caller advising him to wait
about a minute and call back, and reboot the computer.
The last commands in my AUTOEXEC.BAT file would reload
and start the board program.
After some proding by some other sysops who heard about
this, and wanted one themselves, I designed the circuit
described below. I have designed this circuit so that it
can be built from parts which should be available at any
Radio Shack store, not because of any particular fondness
for Radio Shack, but just because this will virtually
guarantee availability of the parts anywhere. The total
cost for all required parts should be less than $20.00.
Parts List:
You will need the following parts.
2 - Opto-isolators similar to Motorola 4N36
1 - Operational Amplifier or Comparitor IC (741, 1458,
TL082, LM358, etc.) (I used an LM358J)
1 - Silicon Diode - Virtually any will do (D1)
1 - 100 nF (0.1 uF) capacitor - min 100 volt rating (C1)
1 - 470 uF capacitor - min 16 volt rating (C2)
1 - 680 ohm 1/4 watt resistor (R7)
1 - 1,000 ohm 1/4 watt resistors (R2)
1 - 10,000 ohn 1/4 watt resistor (R1)
2 - 100,000 ohm 1/4 watt resistors (R4 & R5)
1 - 22,000 ohm 1/4 watt resistor (R3)
1 - 20,000 ohm multi-turn trimpot (R6)
1 - piece of perf-board to build it on
misc wire and hardware for mounting
That's it for the parts you'll need. Now on to my
attempt at a schematic diagram.
Schematic Diagram of Auto Re-Booter
+ 12 v
│
Line 1 ┌───────┐ ┌──────────┐ │
─────────┤ C 1 ├─────┬───┤a c├───┘
└───────┘ ┌─┴─┐ │ │
├───┤ │ Opto- │
│D 1│ │ isolator │
│ │ │ │
Line 2 ┌────────┐ └─┬─┘ │ │ ┌────────┐
─────────┤ R 1 ├────┴───┤k e├────┤ R 2 ├───┐
└────────┘ └──────────┘ └────────┘ │
│
│
┌───────┬───────┬────────────────────────────────────────┘
│ │ │ ┌─┐
┌──┴──┐ ┌─┴─┐ │ │ └─┐ + 12 v
│ C 2 │ │ │ │ ┌───────┐ │ └─┐ │
│ │ │R 3│ └───┤ R 4 ├──────┤ + └─┤
└──┬──┘ │ │ └───────┘ │ └─┐
│ └─┬─┘ │ Op-Amp ├──────┐
G G ┌───────┐ │ ┌─┘ │
┌─────┤ R 5 ├──────┤ - ┌─┤ ┌─┴─┐
│ └───────┘ │ ┌─┘ │ │ │
│ │ ┌─┘ G │R 7│
+ 12v │ └─┘ │ │
│ │ └─┬─┘
│ │ │
┌─┴─┐ │ ┌───────────────────────────┘
│ │ │ │
│R 6│ │ │ ┌──────────────┐
│ │<─────┘ │ │ │ to Reset Switch +
│ │ └──┤a c├───────────────────
│ │ │ │
│ │ │ Opto- │
└─┬─┘ │ isolator │
│ │ │
G │ │ to Reset Switch - (G)
┌────┤k e├───────────────────
│ │ │
G └──────────────┘
Notes: Opto-Isolators
a = anode of LED
k = cathode of LED
c = collector of transistor
e = emitter of transistor
G = ground connections
Op-Amp
+ = non-inverting input
- = inverting input
Theory of operation:
When the phone rings, a voltage of about 80-90 volts,
peak to peak, aproximating a square wave, is placed on
the line. This signal is passed by capacitor C1 and
resistor R1 to the LED of the first opto-isolator causing
it to light on one half cycle. Diode D1 is there to
conduct on the other half cycle. During the time that
the LED is forward biased, and lighted, the
photo-transistor will conduct, charging capacitor C2
through resistor R2. When the phone is not ringing,
capacitor C2 will discharge via resistor R3, at a slower
rate that it is charged at while the phone is ringing.
The voltage on C2 is coupled to the non-inverting input
of the op-amp via resistor R4, and when it becomes more
positive (by just a couple of microvolts) than the
voltage at the wiper of R6, then the output of the op-amp
will rise to about 10.5 volts, causing the LED of the
second opto-isolator to be forward biased, and lit,
causing the photo-transistor to conduct, and the computer
will re-boot just as if you pressed the reset button.
Trimpot R6 is adjusted for the Op-Amp output to go
positive after the desired number of rings. In my own
case, I found that when the voltage at the wiper of R6 is
set to 7.5 volts, with respect to ground, the computer
will reboot on the fourth ring. The higher the voltage
on the wiper of R6, the more rings it will take before
the computer reboots.
CAUTION:
I am using this device on an XT clone, but have been told
by someone else who tried a similar idea on an AT, that
if the reset button is pressed a second time before DOS
gets loaded, it will go into the CMOS setup, and wait for
input from the keyboard. I have no way to test this, so
if you're using an AT or clone, try hitting the reset
button again before DOS gets loaded to see what happens,
BEFORE INSTALLING THIS DEVICE!
DISCLAIMER:
I make no guarantee what-so-ever that the above described
device will work for you, or meet your phone company's
acceptance. Furthermore, I will not be responsible in
any way for any loss of any kind that you may suffer
because of using this device.
The ONLY claim that I make is that I have used the above
described device on my own system, and it works for me.
Closing Statement:
I hope that you will find this device usefull, and if you
do, I would appreciate a note in either the InterLink or
CanConfMail/SmartNet Sysop conference.
Matthew Lewis - Sysop - Media Shack PCBoard
Toronto, Ontario - (416) 699-1846