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                The International Information Retrieval Guild                
 
                                   Presents
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                The IIRG Technical Journal Volume I,  Issue 1                
 Ĵ
          May 1993            /         Editor:  nuis        
 

                    Ŀ
                       - In This Issue of the Journal -   
                    Ĵ
                         The Digital Triggering Timer     
                    


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    OFFICIAL DISLAIMER...

    All information in the IIRG Technical Journal is Member contributed
    material.  The Publishers and Editors of THE IIRG disclaim any liability 
    from any damages of any type that the reader or user of such information
    contained within this journal may encounter from the use of said 
    information.  All files are brought to you for entertainment purposes
    only.  We also assume all information infringes no copyrights and hereby
    disclaim any liability or responsibility.

    IIRG Technical Journal is (C) 1993 by The IIRG
    IIRG and INTERNATIONAL INFORMATION RETRIEVAL GUILD is (C) 1982

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                    Ŀ
                         The Digital Triggering Timer     
                    Ĵ
                     Design and Implementation:    Muther 
                     Technical Quality Assurance:  nuis 
                    


                        ĿĿĿ
                          ô Section 1: Principle ô  
                          
  
Historically the "time bomb" has utilized crude triggering devices such as the
ubiquitous kitchen timer or the anachronistic mechanical alarm clock with 
protruding wires and failure prone mechanisms.

With any luck detonation would occur as scheduled, providing no
electromechanical malfunctions occurred.

Although it was quite easy to isolate a moving hand with a stationary screw 
placed through a plastic lens, the devices were crude, even for their era.
They offered only little accuracy and limited timeframes, generally 12 hours
or less.

There were many influencing factors that determined successful use 
of these mechanisms, including temperature and humidity; for example,
most devices of this type could simply be frozen and rendered inoperative.

By applying modern technology to the issue of triggering mechanisms, far 
more reliable, precise, and surprisingly inexpensive solutions were    
achieved.

The first attempts at employing digital control to triggering mechanisms
achieved large success, much to the chagrin of federal authorities.  These
devices were based upon the early digital chronographs which utilized 
a high voltage output that could easily power a small switching device such
as the transistor.

The 1st generation of digital alarm chronograph used a buzzer type apparatus
powered by a direct current power source, typically a 1.5 volt battery.
The alarm portion needed nothing but a +1.5, and a ground to produce an 
audible signal.  This current made construction of a digital trigger easy,
cheap, effective, and extremely reliable.

Due to widespread availability and ease of construction of explosive devices
utilizing this digital trigger, any terrorist organization could acquire and
assemble this device without drawing undue attention.

As can be imagined, this became the "timer of choice" for such organizations,
as it was clearly far superior to the older style, and could be made small
enough to easily foil conventional security measures.

In response to increasing federal pressure, manufacturers were forced to change
the basic design of the devices to limit usable output current such that the
device would need major modifications in order to be used as a terrorist
device.

The major design revision consisted of altering the current output used to
activate the chronograph's buzzer mechanism to levels that would be
practically useless for driving anything else.

In this document and associated diagrams we will illustrate how the more
modern designs may still be employed for this purpose, with a little
modification, and a little knowledge of electrical engineering.

The device described here has been thoroughly tested and works as stated.
It is based upon a common digital alarm watch, an automotive alarm sound
sensor, and a standard reed relay.


                      ĿĿĿ
                        ô Section 2: Implentation ô  
                        

Materials List

 1) 9 volt battery, alkaline preferred
 2) Standard Bell wire, 22 gage, solid copper core
 3) 1 SPST normally open reed relay, 5 volt operating voltage, 5 amp contact
    rating
 4) 1 watt diode, fast switching
 5) 2 DPDT toggle switches
 6) Indicator beacon (optional)
 7) Automotive alarm glass breakage detector (Most radio/aftermarket shops
    carry this for approx $35.00 U.S.)
 8) 1 El Cheapo alarm watch (Our prototype incorporated a MARLBORO watch that
    was a summertime promotional giveaway for purchasing 2 packs.  Any Kmart
    brand will do fine)
 9) Estes igniter, or blasting cap
10) Black Kat salute for testing, or favorite nitrogen based high explosive

Total of parts should not exceed $50.00 U.S.

Equipment List

 1) 12v DC power source, regulated
 2) 1/4 drill bit
 3) Small finish nail or equiv.
 4) Epoxy, non-metallic type (5 min cure is preferred)
 5) 12v test lamp or volt/ohm meter
 6) Soldering iron, 35 watt max, small tip
 7) Solder, low flux content, small gage (silver mix is avail at radio shack)
 8) Trusty Crucifix (optional)


Assembly


Step 1

Carefully remove the watch back.  The piezo element which actually generates
the audible alarm generally is either wired in place, or held by case
pressure against small springlike protrusions.

Step 2

Remove the piezo element by prying it out of the case back or by unsoldering.
Care is not needed unless you plan to reuse the element at a later time,
otherwise the piezo element can be destroyed.

Step 3

Pierce two small holes through the watch case with the finishing nail heated
with a lighter (plastic back) or drill a 1/4 inch hole in metal case back.
The larger opening for the metal back models ensures that the wires will not
become pinched and short, and also allows for the epoxy to seep in for securing
at a later step.

Step 4

Thread the wire through nail holes or through case back and solder to
the original wire or springlike protrusions that butted up to the piezo
element.  Solder carefully, using as little heat as possible to avoid circuit
damage, but make sure the joint is shiny and strong.  There should be no lumpy
solder blobs anywhere on the board.

Step 5

Carefully place the back on the watch temporarily to seat the wiring.
Remove the back, and inspect for insulation damage or pinching.  If all
is well, then a slight epoxy mixture may be applied to the board in order
to hold the wiring securely to the inside of the case (not the back).
The epoxy will provide needed strain relief for this part of the device.

Wait until this cures before continuing.

Step 6

Secure the watch back, and inspect for proper external button operation.
Since we know some of you who are not careful have already epoxied the metal
buttons and have rendered them inoperable, you must start again from Step 1
(this time be more careful).

Those of you whose watches perform as well as they did before you started,
i.e., the set buttons work ok, the date/time button is ok, the light is ok,
etc., may move on to Step 7.

Step 7

In this step we will determine how your glassbreak sensor works.  This STEP
is critical.  Failure to determine startup output can result in loss of limbs.

Adjust the sensitivity setting on the detector to MIN, and apply power to the
unit.  99 percent of the detectors on the market have a status led.  Read the
instructions included with the unit to determine output polarity.  Some may be
switchable, some may have a polarity wire, and some only an output wire (these
units generally output ground @ 100ma Max Load).  In any event, while applying
power, watch the status LED.  NOTE IF IT LIGHTS when power is first applied.
This is critical.  Also eye your volt/ohmmeter.  Set it to "locking" if your
model supports this feature, and watch as you power up.  One end should go to
the positive, the other to the detector output wire (blue or gray most of the
time).  NOTE the meter reading.

Step 8

If you were fortunate enough to buy a unit with a detachable mike, you are
luckier than the poor sap who must take his apart to desolder the surface
mounted mike from the pc board.

Cut the mike off and solder the wires from the watch to the 2 wires which used
to attach to the mike.  Polarity is unimportant, but check just to be on the
safe side.

Once connected, and taped or heatshrinked together, the watch can be epoxied
to the top of the detector.  When mounting, be sure to locate the watch such
that access to the inside of the detector and any external adjustment holes or
knobs is not restricted.

Step 9

Some units have wires inside to expand the "listening" range of the detector
to match different glass manufacturers processes.  This wire may be orange or
purple.  It is like an "expand" button is to a stereo.  Do not cut this until
ready for testing.  Some units need it cut, some don't.  Let's see what your
watch outputs for a frequency first.

Power your detector and set your watch to alarm test mode (usually by holding
2 buttons together at once).  You should see the detector light come on at this
time.  If not, turn up the sensitivity to MAX, and try again.  You may want to
add a slight load to the output wire (such as an LED), but be sure to use a
resistor in order to prevent burnout.  Remember, the unit will output ground
with the forward voltage being applied by the supply.

Test again.  If your unit lights this time, BRAVO halfway home now.  If not,
then the last resort is to cut the sensitivity "expand" mentioned earlier.  If
it works now, then you're set; if not, you're SOL.  Give up now, 'cause you
should have never started this project without knowing what the fuck you were
doing in the first place.

The sensitivity setting should be set to as MIN as possible, but still function
everytime an alarm test is made.

Step 10

A SPST switch must be placed inline at the output wire of the detector.
Why?  Refer back to the output levels read when the detector was first tested
for output.  When a glass detector is first powered up, the output usually
engages for a brief instant... KABOOM without the switch.  Look at your NOTES
taken in Step 7..... did you see the ground come in for an instant?  You MUST
isolate the startup with a switch.  Diagram 2 illustrates the proper
implementation.

Revisions to the switch may be made, such as a simple or time delayed relay
action.  However, as a safety precaution, the diagram uses a positive, less
dangerous mechanical approach.

The outputs should be sent to a relay, and isolated by a switch.  A diode is
used to prevent the relay from dragging the ground from the glassbreak sensor
unit and causing a malfunction.

Diagram 2 will provide you with the rest of the construction details.  The
9 volt battery powers the glass detector for 30 hours, and will have
sufficient voltage to fire the igniter and relay for 2 attempts, after
which it should be replaced.  Alternatively, two 9 volt batteries may be used,
but the initial draw of the glass detector will still drain the first in the
30 hour timeframe.




Comments and suggestions about this and future issues of the IIRG Tech
Journal are welcome.  Contact nuis at the IIRG WHQ, the Rune Stone.


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                  The IIRG Technical Journal (C) IIRG'1993
                        - May Odin Guide Your Way -
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