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Leads
If you are
new to electronics you will need to know what a lead is. A lead
is simply a wire used to connect two parts electrically. The method of
clipping the lead to the component (part) determines its name. An alligator
clip test lead uses a small metal clothespin for connecting, while
a mini-hook clip lead is like a small, spring-loaded crochet hook.
The mini-hook is best for attaching to a wire, the alligator clip is best
for larger connections like to the test surfaces.
Leads come
in many different lengths and are carried by all electronics stores.
The testing
device consists of four parts the test surfaces, probe and handhold,
speaker, and circuit. These are connected by leads. The first item to
construct is the test surfaces.

Test Surfaces
You will
need two plates to set test samples on. The plates that hold the samples
are intentionally separated from the main circuit because, unless you
add shielding, the frequencies on the test plates may interfere with the
circuit.
Materials
needed:
- shoe box
- aluminum
foil
- stiff
paper
- 2 bolts
and nuts
- nail
- 4 alligator
clip test leads (3 very short, 1 about 24 inches)
- 2 ordinary
light switches.
Acceptable:
Cut two 3 1/2 inch squares out of stiff paper such as a cereal box. Cover
them with slightly larger squares of aluminum foil, smoothed evenly and
tucked snugly under the edges. You have just made yourself a set of open
capacitors.
Mount two
ordinary light switches on the front side of the shoe box, one in front
of each plate. Cut 1 by 1/2 inch rectangular holes to let the toggle through.
Remove the screws that came with the switch, then insert the switch from
inside so that OFF is when the toggle is UP (this is the reverse of how
most light switches are oriented). Push a pin from the inside thorough
the screw holes, enlarge them, and replace the screws from the outside.
If the shoe box is too shallow, flex the "ears" off the switches.
On the shoe
box, label the left plate "Substances" and the right plate "Tissues".
Label the toggle for each plate with an "OFF" and "ON".
Using a short
alligator clip test lead, attach the tissue plate bolt to the tissue switch
at one screw terminal. If there are three screw terminals, one will be
green for ground - do not use it, use the other two. Attach the other
screw terminal on the tissue switch to the substance plate bolt. Attach
the substance plate bolt to the substance switch at one screw terminal.
Finally attach a long alligator clip test lead to the other substance
switch screw terminal. The other end will be attached to the circuit when
you build it.
Choose either
the "Acceptable" or the "Best" construction technique.
You do not have to do both.
Best:
Use a large plastic project box instead of the shoe box. Do not use project
boxes with metal lids. If you can not find all plastic boxes, remove the
metal top and mount the test plates to the bottom. Use insulating sleeves
and solder all connections.

Probe
And Handhold
These are
what you grasp when testing. The places to attach the probe and handhold
are described with the circuit instructions.
Acceptable:
For the probe use an empty ball point pen (no ink) with a metal collar
by the point. Connect a two or three foot alligator clip test lead to
this collar. For the handhold use a cheap metal can opener (the kind that
fills your hand) with a second alligator clip test lead attached.
Best:
The Archer Precision Mini-Hook Test Lead Set has a banana plug for the
probe on one end and a mini-hook on the other end for easy attachment
to the circuit. Tape a long, new pencil to the probe; this makes it easier
to hold. The best handhold is simply a 4 inch piece of 3/4 inch copper
pipe (which a hardware store would just saw off for you) connected to
the circuit with a three foot alligator clip test lead.
Banana Plug
Probe = Radio Shack #278-1160A Precision Mini-Hook Test Lead Set

Speaker
Hearing is
believing. The sound made when you test substances lets you know if you
have a YES (positive) or NO (negative). The better the sound quality the
easier it is to hear the difference.
Acceptable:
You may hook the circuit up to your stereo system. Make sure you ask an
expert to make the attachment. The leads (wires) you need to do this depend
on the terminals your stereo has, but the end of the lead to the circuit
should have either alligator clips or mini-hooks for easy attachment.
Turn the bass all the way down, and the treble all the way up when you
use it. Headsets do not work.
Best:
The Archer Mini Amplifier Speaker is inexpensive and small (about the
size of a transistor radio), making it easy to take with you. It needs
a 9 volt battery. Remove the screw at the center back of the speaker using
a Phillips screw driver to gain access to the battery compartment. Also
get an 1/8 inch phono jack. Plug the phono jack into the receptacle marked
"INPUT", and unscrew the plastic housing on the jack to expose
the two posts for attaching wires. Each post should have a small hole
in it to attach a mini-grabber lead. If there are no holes use alligator
clip leads, but slip a piece of plastic tape between the posts to make
sure the alligator clips do not touch each other.
You are
now ready to build the main circuit.
Materials
needed:
- shoe box
- tape
- nail
- pointed
knife
- cheap
wire stripper (if needed)
- paper
clip

Parts
List
| Item |
Radio
Shack # |
| Ordinary
light switch |
|
| Potentiometer
(variable resistor), 50k ohms |
271-1716 |
| Knob
to fit potentiometer |
274-428 |
| .1 microfarad
ceramic disk capacitor |
272-1432A |
| .0047
microfarad ceramic disk capacitor (.005 will do) |
272-130 |
| MPS2907
PNP silicon transistor or equivalent |
276-2023 |
| Audio
output transformer 900 CT: 8 ohm |
273-1380 |
| 3 size
AA batteries |
|
| Battery
holder for 4 AA's (3 AA battery holder will do) |
270-391
has 2 wires coming away from it, one red (for +), one black (for -). |
| Microclip
test jumpers |
278-017
(you need 6 packages of two) |

Directions
- Get a
shoe box, save the lid, print
the picture above and tape it to the bottom (inside) of the box.
- Mount
the light switch (a) just like you did for the test plates on the front
of the shoe box. Mount it in the regular way so that ON is UP and label
the box clearly. Turn light switch OFF before continuing.
- Pierce
a hole with a large nail or pencil for the shaft of the potentiometer
(b), and a smaller hole for the tab on the side of the potentiometer
(the tab keeps the potentiometer from rotating when you turn the switch).
Remove the nut and washer from the base of the potentiometer shaft,
insert the shaft into the hole from inside of the shoe box. Trim the
excess cardboard around the shaft with a knife. Replace the washer,
nut and tighten securely.
- Attach
the knob (c) to the shaft. Use a very small screw driver or pointed
knife to tighten.
- Pierce
holes in the box with a pin for the .1 microfarad capacitor (d) and
the .0047 microfarad capacitor (e). Push the wires of each capacitor
through the holes from the outside. When the ceramic part is almost
touching the box, bend the wires inside to keep it in place. The capacitors
look very much alike, so be careful not to switch them (open one capacitor
package at a time and put the part directly in place, double checking
the diagram).
- Pierce
the holes for the transistor (f). Examine the transistor. Hold it in
your left hand with the flat side on the let and wires pointing up at
you. Notice that the center wire is the "base". Bend the base
wire away to the left slightly so you will be able to insert the transistor
into the triangle of holes. A diagram on the transistor package tells
you that the top wire is the "collector" and the bottom wire
is the "emitter". Insert the transistor from the outside of
the box so each wire goes where it is supposed to=, and bend the wires
sideways to secure.
- Pierce
seven holes for the transformer (g). There should be 2 wires on one
side and 3 on the other. All wires should have the ends bared and available
for connections. If they are not, strip away 1/4 inch of insulation
and twist the strands together on each wire to keep them neat (practice
using the wire stripper, first on a different piece of wire). Notice
that the transformer has 2 little mounting tabs. Push them through the
box and bend them down with a knife or screwdriver on the inside to
keep the transformer firmly in place or tape the transformer to the
outside of the box. Then thread the 5 wires through their respective
holes.
- Prepare
the battery holder (i) by cutting the wires to no more than two inches.
Bare the ends of the wires for 1/4 inch. You will only use three batteries,
so in one of the battery slots, fill the space with a paper clip. Straighten
one end of the paper clip. Hook the other end to the spring, and thread
the straight part though the hole on the other side. Then bend the straight
part down on the outside, out of the way.
- Next,
insert three AA size batteries (h) in the holder (i) (note the plus
(+) and minus (-) ends are marked on the holder). Notice that one wire
is red (for positive) and one is black (for negative). Don't let the
bared ends of the two wires touch. Pierce the holes for the battery
wires and insert from the outside. Tape the battery holder to the outside
of the box. If your batteries get warm remove them and recheck your
connections. Now to connect everything.
- Use 9
microclip test jumpers (j) to make the nine connections drawn. Note
that connection 6 needs an alligator clip lead to the light switch.
Pull on each connection after you make it, and stuff the extra wire
through a slit made in the side of the she box with scissors. Make slits
wherever you need them. Then clip the lead from your test plate shoe
box to the capacitor where shown. Next attach the probe and handhold
where shown. Finally attach the speaker where shown. In the picture
there are both mini-hook and alligator clips depicted, but it is not
important which kind you use, only that you make secure connections.
- Test the
circuit. Turn the speaker on, and the volume half way. Turn the Syncrometer
(light switch) ON. Test the circuit by briefly touching the probe to
the handhold. The speaker should produce a should like popping corn
(readjust speaker volume to a comfortable level). If you hear nothing,
go over each step carefully. Make sure the batteries are fresh. Recheck
all connections, especially ones made to stripped wires. Replace the
lid and turn the shoe box over so it sits on its lid.
- Label
the potentiometer. Turn the knob almost fully clockwise. Mark the box
where the line on the knob points. Grasp the handhold in one hand and
press the probe with your thumb. Listen to the pitch. Now turn the knob
almost fully counterclockwise, mark the box, and listen to this pitch.
Whichever pitch is higher label MAX (maximum) on the box.
- You did
it! Turn off the speaker and the Syncrometer.

After you
have used the Syncrometer for a while you may wish to take your device
to an electronics shop and ask someone to mount the components in an all
plastic box and solder the connections. This would let you travel with
it in your suitcase without mashing it into a jumbled mess of wires.
Syncrometer
Schematic

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