12/19/91 11:14pm

Basic Eavesdropping #1
The Electronic Ear
------------------
Written By The Freddy
In Association With The National Newtwork of Anarchists and Nihilists (NNAN)

Introduction
------------
	This text file is the first in a series on the topic of eaves-
dropping.  My trusty Webster's Compact Dictionary defines eavesdropping as
the art of listening secretly.  This can be useful to the young anarchist
in many ways.  Suppose that, as a beginning phreak, you are given the
undubious assignment of being the lookout.  Well, you want to hear the
guard coming while being as far away as possible.  Or you stake out your
mark's house to find out as much as you can before you get your revenge.
Well, again, you want to hear as much as possible without making yourself
known.  To find out how to properly accomplish these and many other tasks,
read on.

Disclaimer
----------
This document was intended for informational purposes ONLY, the author and
the National Network of Anarchists and Nihilists do not endorse or support
any illegal action presented here or in any other documents which we
release.  The only motivation for the writing of this document is purely
for educating the general public.  The author and the National Network of
Anarchists and Nihilists will not be held responsible for any actions by
the reader of this document.

Description
-----------
	The Electronic Ear is alot like those "high tech" Listenaiders
which boost sound.  Think of the possibilities.  With the Electronic Ear
you can hear whispers 500 feet away or a conversation half a block away.
You can listen in and record for all posterity the conversation on the tape
of your choise.  Of course, it is illegal to listen in on and/or record a
conversation without the permission of the parties doing the conversing.
Two versions will be presented.  One that uses a parabolic dish (like on
satellites); the other uses a highly directional shotgun microphone.  Both
use the same easy to build superamplifier circuit.

Parts List
----------
Amplifier Circuit
-----------------
R1        10 k-ohm resistor
R2        100 ohm resistor
R3        4.7 M-ohm resistor
R4,R6     3.3 k-ohm resistor
R5        220 ohm resistor
C1        220 pF disc
C2,C3,C5  0.47 æF disc
C4        1.0 æF polarized electrolytic
IC1       LM387 integrated amplifier IC
D1        1N34A
S1        SPST switch
Mike      Electret condenser microphone
(1)       Project box, 2 3/4 by 5 1/8 by 1 3/4
(1)       1/8 inch microphone input audio jack
(1)       1/8 inch sound output audio jack

All resistors are 5 to 10 percent tolerance, 1/4 watt.
All capacitors are 10 to 20 percent tolerance, rated at 35 volts or more.
LM387 amp is available in kit form from:

	ALLEGRO ELECTRONICS SYSTEMS
	3E MINE MOUNTAIN
	CORNWALL BRIDGE, CT 06754
	(203)672-0123

Mail order company.  Catalog available.

Construction Of The Amplifier Circuit
-------------------------------------
	The Amplifier Circuit is based on an LM387 dual preamp IC.  In
layman's terms, the preamp first increases the amplification from the
microphone about 47,000 times, and then limits the audio signals of only 1
volt peak to peak or less to go to the output jack.  This will save your
ears in case one of your less scrupulous friends shoots a cap gun in front
of the mike.  Use a universal solder board for the circuit.
	Construction is pretty straightforward.  I have included both the
schematic and a picture of what the finished circuit should look like.

Schematic Of The Amplifier Circuit
----------------------------------

      C6 220pF                     o  To tape         Power supply
  ----|(--ground                   |  circuit         decoupling/filtering
  |                          C5   \./   or                   C2
  |                       .47 æF  --- headphone           ---|(---
  |                                |  amp                 | .1æF |
  |           ----o----------------o                V+ o--o--|(--o--ground
  |           |   |                |                         C1
  |      D1   \/  |                |                       1000æF
  |    1N34A  -   |                |
  |           |   |                |                  Recorder interface
  |___________o   |                |                      J1
              |   |                |                     (o)------
          R5  /   /  R6            |                   Tip|      |
      220 ohm \   \ 3.3 k-ohm      |5                     \/     |
              /   /                /\               ---/\/\/\/---o--ground
              \   \              /    \             |     R1
              |   |            /        \           o    10 k-ohm
     S1       ----o        6 /    IC1b    \ 3
 o-o  /o--o-------| -------/     LM387      \-------o-ground
    /     |       |      /--------------------\     |
          |       |            |7      |8  C4 1.0 æF|
          |       |            |       |       +    |
          |       |------------o       |----o---|(---
          |                    |            |
          |             R4     /            |
          |          3.3 k-ohm \            |
          |                    /            |
          |                    \            |
          |                    |            |
          |                   \./  C3       |
          |                   ---.47 æF     |
          |                   +|            |         Headphone amp
          |                    |            |              J1
          |  ------------------o            |             (o)-------
          |  |                4|            |           Tip|       |
          |  /                 /\           |              |       |
          |  \ R3            /    \         |        C2   \./      |
          |  / 4.7 M-ohm   /        \       |       4.7æF ---      |
          |  \           /    IC1a    \     |              |  C1   |
          |  |          /     LM387     \   |              | .1æF  |
          |  |        /-------------------\ |              o--|(---o
          |  |            2|       1|       |       Q1     |       |
          |  --------------o        ---------     2N2222   |       |
          |                |                      c      e |  R4   |
          |          R2    /        V+ o------o----\    /--o-\/\/\-o-ground
          |       100 ohm  \                  |      \/     1 k-ohm|
          |                /              R2  /     ----           \
          |                \          22 k-ohm\      b|        R3  /
          |                |                  /       |    27 k-ohm\
          |          C2   \./                 \       |            /
          |        .47 æF ---   C1            --------o-------------
          |     R1         |   220 pF                 \
          |----\/\/\/\-----o----|(-------             / R1
                10 k-ohm   |            |             \ 1 k-ohm
                           |   ---------o---ground    /
                           |   |                      |
                           Mike                       o

Suggested Parts Layout
----------------------
       Headphnone    Mike Jack
       Jack_____     _____
         --|   |-----|   |------------------------------------------------
         |  | |       | |                                  --------      |
  ON/OFF |  ---       ---                             _____|______|____  |
  switch ---  ______________________________________  |               |  |
      O--| |  |     __________                     |  |               |  |
         ---  |   -|__________|-          _|_ _|_  |  |               |  |
         |    |                           | | | |  |  |               |  |
         |    |   ____/------------\____  | | | |  |  |               |  |
         |    |       \------------/      | | | |  |  |    Battery    |  |
         |    |                           | | | |  |  |               |  |
         |    |     _|_                   -|- -|-  |  |               |  |
         |    |     | |       _   _   _   _        |  |               |  |
         |    |     | |     _|_|_|_|_|_|_|_|_      |  |               |  |
         |    |     | |     |               |      |  |               |  |
         |    |     | |     |               |      |  |               |  |
         |    |     -|-     |_______________|      |  |               |  |
         |    |              |_| |_| |_| |_|       |  |               |  |
         |    |     Circuit board                  |  |               |  |
         |    --------------------------------------  |               |  |
         |                                            -----------------  |
         |_______________________________________________________________|


Notes
-----
	If you cannot understand the schematic, then get a friend to make
it for you.  You should be able to build the circuit with a minimal amount
of electrical experiance.
	If you plan to connect the output to the line input of a tape
recorder, use a 10 k-ohm potentiometer as a level control and be sure to
use shielded cable to reduce unwanted hiss.
	Test the circuit before building the rest of the Electronic Ear.
Connect a electret condenser mike to the input jack and a pair of
headphones to the output.  Don't put the headphones directly over your
ears.  I found this out the hard way.  Turn the circuit on and listen for
the squealing sound of the oscillating circuit.  If you don't hear it, go
to the next step.  If there is an oscillation problem, increase the value
of C6 to 330 pF or 470 pF.  Also try increasing R5 from 220 ohms to a
higher value that will reduce or eliminate oscillation, but it will also
decrease the gain of the circuit.  If oscillation is still a problem, then
try replacing R3 with a 1.5 m-ohm resistor.  This should decrease the
overall gain of the circuit.

The Parabolic Dish
------------------
Parts List
----------
1     Spun aluminum or plastic parabolic dish
1     10 inch length of 12 gauge wire
2     #12 crimp on connector

Dish available from:

	EDMUND SCIENTIFIC CO
	P.O. BOX 5408
	SCOTTSDALE, AZ 85261
	(609)573-6250

Mail order company.  Catalog available.

Construction Of The Parabolic Dish
----------------------------------
	The most effective way of tuning in on distant sounds is to use a
parabolic dish.  I used an 18 inch diameter dish purchased surplus from
Edmund Scientific.  Other dishes, both metal and plastic, will do.
	The microphone must be positioned at the focal point of the dish.
You could use the complicated algebra method, but an easier way is to
position the dish in full sunlight and move  small piece of paper in and
out of the center until you see a small, bright spot.  Measure the distance
from the paper to the base of the dish and you have the focal point.  If
the dish is not reflective, try covering it with aluminum foil.
	You want to mount the microphone to a standoff.  This can be made
from a coat hanger adjusted to fine tune the focal point.  The microphone
should be physically insulated from the standoff using double sided tape.
The finished standoff and mike should look like this:

               _________
              /         \
             |            \
             |            |
             |           |-|   
    Coat     |           | | Crimp-on spade
    hanger   |           | | connector (bend  
    bent     |         --|-| out tongue)
    to       |
    shape    |
             |  
             |
             |
             |
            |-|
            | |  Crimp-on spade
            | |  connector
            |-|
            |

	Attach the amplifier to the side of the dish using some hardware or 
double sided tape.  
	Paint the dish flat black so it does not glint in the sunlight.  
Also, add a 1/4" 20 bolt and sleeve coupling to one side of the dish to 
provide a meansto secure it to a tripod.  This works quite well.

                      _
                    /
                 /  Parabolic
              /     dish
  Amplifier  /
   circuit  /  
       |---/
       |   |
       |   |--\      o\
       |   |    \-----/
       |---\
             \
              \
                \  
                /\\  
              /    \\_
               \  /
               |__|
              /    \
            /        \   Tripod
          /     /\     \

The Shotgun Mike
----------------
Parts List
----------
1     40 inch lenght of 4 inch PVC or ABS plastic pipe
1     4 inch end cap to fit onto one end of pipe
1     3 inch round speaker (replaces Mike)

Construction Of The Shotgun Mike
--------------------------------
	The Shotgun Mike is cheaper to build than the parabolic dish.  It 
does not collect as much sound, though, but it is more directional.
	The speaker needs to be physically isolated from the tube to reduce 
the effects of vibration.  I have found that a pice of 2 inch thick foam 
cut to 4 1/2 inches in diameter works well.  Punch or cut out a small 
circle in the center so it looks like a doughnut.
	Solder an 8 inch length of shielded cable to the terminals of the 
speaker.  Press the magnet of the speaker through the small hole and slip 
the foam and speaker into one end of the tube.
	Solder the other end of the speaker wire to a 1 1/8 inch plug.  
Drill a hole in the end cap for the speaker wire, mount the amplifier, and 
you're set.  The finished product should look like this:

  Amplifer                                     PVC pipe
  circuit   ---------------------------------------------------
  ##########||----|   /                                            
  ##########|| F  |  / Speaker
  ##########|| o  |-| 
  ##########|| a  |-|
  ##########|| m  |  \
  ##########||----|   \
            --------------------------------------------------

Conclusion
----------
	Now that you know how to build an Electronic Ear, you probably want 
to know how to use it.  That will be upcoming in a future installment.  
Until then, build one yourself.  I can be reached at The DeaTh BoX 
BBS--(714)970-6710--which is the home of NNAN.  Well, it's getting late so 
until next time, adieu.

12/24/91 1:27am
