Elenco Electronics K-44 User guide

LIE DETECTOR KIT
MODEL K-44
Assembly and Instruction Manual
ElencoTM Electronics, Inc.
Copyright © 2003 ElencoTM Electronics, Inc. 753116

PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this Lie Detector kit from a distributor, catalog, etc., please contact Elenco™ Electronics
address/phone/e-mail is at the back of this manual) for additional assistance, if needed.
RESISTORS
Qty. Symbol Value Color Code Part #
1 R3 1kW5% 1/4W brown-black-red-gold 141000
1 R2 100kW5% 1/4W brown-black-yellow-gold 161000
1 R1 1MW5% 1/4W brown-black-green-gold 171000
1 VR1 900kWPotentiometer 191695
CAPACITORS
Qty. Symbol Value Description Part #
1 C1 .022mF (203) Disc 242010
1 C2 47mF Electrolytic 274744
SEMICONDUCTORS
Qty. Symbol Value Description Part #
1 U1 LM555 /LM1455 IC (Integrated Circuit) 330555
1 D1 LED (Light Emitting Diode) 350002
MISCELLANEOUS
Qty. Symbol Description Part #
1 PC Board 518044
1 Speaker 64W520813
2 SW1, 2 Slide Switch 541102
24” Solder 63/37 551124
1 Battery Holder 590096
2 Washer 8mm x 14mm 645101
1 Socket 8-pin 664008
1 Foam Tape 740020
1 Speaker Pad 780125
1 Wire 22 AWG Stranded 814001
-1-
Resistor
Capacitor
Potentiometer
PARTS IDENTIFICATION
Discap Electrolytic
(–) (+)
LED Speaker 64W
W
Switch
IC Socket 8-pin
Integrated
Circuit
Battery Holder
Speaker Pad
Washer

-2-
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in properly identifying the value of resistors.
BAND 1
1st Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
BAND 2
2nd Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
Multiplier
Color Multiplier
Black 1
Brown 10
Red 100
Orange 1,000
Yellow 10,000
Green 100,000
Blue 1,000,000
Silver 0.01
Gold 0.1
Resistance
Tolerance
Color Tolerance
Silver +10%
Gold +5%
Brown +1%
Red +2%
Orange +3%
Green +.5%
Blue +.25%
Violet +.1%
BANDS
12 Multiplier Tolerance
IDENTIFYING CAPACITOR VALUES
Capacitors will be identified by their capacitance value in pF (picofarads), nF (nanofarads), or mF (microfarads). Most
capacitors will have their actual value printed on them. Some capacitors may have their value printed in the following
manner. The maximum operating voltage may also be printed on the capacitor.
Second Digit
First Digit
Multiplier
Tolerance The letter M indicates a tolerance of +20%
The letter K indicates a tolerance of +10%
The letter J indicates a tolerance of +5%
FortheNo.01234589
Multiply By 1 10 100 1k 10k 100k .01 0.1
Multiplier
Note: The letter “R” may be used at times
to signify a decimal point; as in 3R3 = 3.3
103K
100V
Maximum Working Voltage
The value is 10 x 1,000 = 10,000pF or .01mF 100V
10mF 16V
METRIC UNITS AND CONVERSIONS
Abbreviation Means Multiply Unit By Or
p Pico .000000000001 10-12
n nano .000000001 10-9
mmicro .000001 10-6
m milli .001 10-3
– unit 1 100
k kilo 1,000 103
M mega 1,000,000 106
1. 1,000 pico units = 1 nano unit
2. 1,000 nano units = 1 micro unit
3. 1,000 micro units= 1 milli unit
4. 1,000 milli units = 1 unit
5. 1,000 units = 1 kilo unit
6. 1,000 kilo units = 1 mega unit

-3-
The heart of the Lie Detector is the 555 IC. The 555
timer has become one of the basic and extremely
successful chips in the semiconductor field.
Understanding this device will prove most helpful,
as you will surely encounter its use many times in
the future.
THE 555 IC TIMER
The block diagrams and pin connections of the 555
chip are shown in Figure 1. In the Lie Detector, the
555 timer operates as an astable multivibrator or
free-running oscillator. It generates a continuous
output of high and low pulses. Resistors R1, R2,
VR1 and capacitor C1 determine the frequency at
which it oscillates. The combination of components
are called an RC circuit. If you vary the resistor or
capacitor, you will change the frequency or pitch of
the oscillator. In the LOW mode, the circuit
oscillates from 16 to 31Hz, and 35 to 600 in the
HIGH mode.
Placing resistance across the two washers (P1, P2),
causes the circuit to oscillate. As the resistance
changes, so does the frequency. Your body GVR
(galvanic skin resistance) is placed in the circuit
when you hold the two washers. Under stress, your
GVR decreases, causing the oscillator frequency to
increase. If you were to let go of the washers, the
oscillator would stop. The output at pin 3 may be
high or low.
To change the sensitivity, the circuit has a LOW and
HIGH switch (SW1). In the LOW position, resistor
R1 (1M) is placed in series with the trim pot. A
greater change in resistance is needed to affect the
oscillator frequency. In the HIGH position, resistor
R1 is removed and a change in resistance across
the washers is easily detected. You can adjust the
sensitivity in either mode using trim pot VR1.
The output of the 555 timer appears on pin 3 as a
square wave, which drives the speaker and LED.
The speaker and LED are not connected to pin 3
directly, but through a coupling capacitor (C2) and a
current limiting resistor (R3). As the output goes
high and low, this causes the speaker to sound and
the LED to flash at the same rate.
CIRCUIT OPERATION
GND
TRIGGER
OUTPUT
RESET 4
3
2
1
5
6
7
8+Vcc
DISCHARGE
THRESHOLD
CONTROL
VOLTAGE
UPPER
COMPARATOR
INTERNAL
VREF
Q2
– +
OUTPUT
BUFFER
2 VCC
3
R
R
VCC
3
Q1
CONTROL
FLIP-
FLOP
LOWER
COMPARATOR
– +
R
S Q
R Q
RESET
Figure 1

-4-
Introduction
The most important factor in assembling your K-44 Lie Detector Kit is good soldering techniques. Using the
proper soldering iron is of prime importance. A small pencil type soldering iron of 25 - 40 watts is
recommended. The tip of the iron must be kept clean at all times and well tinned.
Safety Procedures
• Wear eye protection when soldering.
•
Locate soldering iron in an area where you do not have to go around it or reach over it.
•Do not hold solder in your mouth. Solder contains lead and is a toxic substance. Wash your hands
thoroughly after handling solder.
• Be sure that there is adequate ventilation present.
Assemble Components
In all of the following assembly steps, the components must be installed on the top side of the PC board unless
otherwise indicated. The top legend shows where each component goes. The leads pass through the
corresponding holes in the board and are soldered on the foil side.
Use only rosin core solder of 63/37 alloy.
DO NOT USE ACID CORE SOLDER!
CONSTRUCTION
Solder Soldering Iron
Foil
Solder
Soldering Iron
Foil
Component Lead
Soldering Iron
Circuit Board
Foil
Rosin
Soldering iron positioned
incorrectly.
Solder
Gap
Component Lead
Solder
Soldering Iron
Drag
Foil
1. Solder all components from
the copper foil side only.
Push the soldering iron tip
against both the lead and
the circuit board foil.
2. Apply a small amount of
solder to the iron tip. This
allows the heat to leave the
iron and onto the foil.
Immediately apply solder to
the opposite side of the
connection, away from the
iron. Allow the heated
component and the circuit
foil to melt the solder.
1. Insufficient heat - the
solder will not flow onto the
lead as shown.
3. Allow the solder to flow
around the connection.
Then, remove the solder
and the iron and let the
connection cool. The
solder should have flowed
smoothly and not lump
around the wire lead.
4. Here is what a good solder
connection looks like.
2. Insufficient solder - let the
solder flow over the
connection until it is
covered. Use just enough
solder to cover the
connection.
3. Excessive solder - could
make connections that you
did not intend to between
adjacent foil areas or
terminals.
4. Solder bridges - occur
when solder runs between
circuit paths and creates a
short circuit. This is usually
caused by using too much
solder. To correct this,
simply drag your soldering
iron across the solder
bridge as shown.
What Good Soldering Looks Like
A good solder connection should be bright, shiny,
smooth, and uniformly flowed over all surfaces.
Types of Poor Soldering Connections

ASSEMBLE COMPONENTS TO THE PC BOARD
-5-
D1 - LED (light emitting diode)
(see Figure A)
VR1 - 900kWTrim Pot
(see Figure B)
U1 - 8-pin IC Socket
U1 - LM555 Integrated Circuit
(see Figure C)
C1 - .02mF or 0.22mF
(203 or 223) Discap
R1 - 1MW5% 1/4W Resistor
(brown-black-green-gold)
SW1 - Switch
(see Figure D)
R3 - 1kW5% 1/4W Resistor
(brown-black-red-gold)
C2 - 47mF Electrolytic Capacitor
(see Figure E)
R2 - 100kW5% 1/4W Resistor
(brown-black-yellow-gold)
SW2 - Switch
(see Figure D)
Wire/Washers (left & right hand)
(see Figure F)
Figure A
Mount the LED with the flat side in
the same direction as marked on
the PC board.
Flat
Mount flush
with PC board
Figure C
Insert the 8-pin IC socket into
the PC board in the direction
shown. Solder and cut off
excess leads. Then, insert
the LM555 IC into the socket
in the same direction shown.
Figure B
Mount the 900kWpot to the PC
board as shown. Solder and cut
off the excess leads.
Figure D
Cut the tabs off of the switch
as shown.
Figure E
The electrolytic capacitor has polarity. Be sure
to mount it with the negative (–) lead (marked
on side) in the correct hole. Bend the capacitor
as shown.
Polarity
Marking
1/8”
IC LM555
PC Board
IC Socket Figure F
Cut the wire in half. Strip 1/4” of insulation off of
one end and 1/2” off of the other end.
Loop the 1/2” end around the washer and then
solder it. Solder a wire to the PC board marked
Left Hand and a wire to Right Hand.
Knot the wires as shown to create a strain relief.
Tab Tab
Looped
Wire
Solder
Knotted
Wires

-6-
ASSEMBLE COMPONENTS TO THE PC BOARD (continued)
Speaker
Remove the backing from one side of the
speaker pad and then attach it to the speaker.
Remove the second backing and attach the
speaker to the PC board as shown.
Solder the speaker wires to points A and B on
the the PC board as shown.
Battery Holder
Bend the battery holder leads as shown below.
Remove the backing from one side of the foam tape. Attach the
foam tape to the battery holder as shown.
Remove the second backing and attach the holder to the PC board
as shown.
Solder the battery holder’s two leads to the PC board as shown. Cut
off the excess leads.
Speaker
Speaker Pad
PC Board
Black Wire
Red Wire
Point B
Point A
Foam Tape
Battery Holder
Foam Tape
Backing
Foam Tape
Backing
Solder
Bend Leads
Figure G Figure H
TESTING
1. Be sure that all components have been mounted
in their correct places.
2. Check that the electrolytic capacitor C2 has been
installed correctly.
3. Be sure that the LM555 IC U1 has been installed
correctly.
4.
Check all solder connections. Solder should flow
into a smooth puddle rather than a round ball.
Resolder any connection that has formed into a ball.
5. Have any solder bridges formed?
6. Check the battery voltage.
TROUBLESHOOTING
Contact ElencoTM Electronics if you have any problems. DO NOT contact your place of purchase as they will
not be able to help you.
Set VR1 fully counter clockwise, switch SW1 to
LOW, and SW2 to OFF. Insert a 9V battery and set
SW2 to ON. The LED lights and you should not
hear any sound from the speaker. Short the two
washers, the speaker sounds as the LED flashes.
Adjust VR1 clockwise and the frequency increases.
Set SW1 to HIGH and adjust VR1 the same way.
Note, you do not hear the tone when VR1 is fully
clockwise in the HIGH mode. After testing the unit
is complete, go on to Operation on the next page.

ElencoTM Electronics, Inc.
150 W. Carpenter Avenue
Wheeling, IL 60090
[phone]
http://www.elenco.com
e-mail: [e-mail]
SCHEMATIC DIAGRAM
OPERATION
Turn the unit on, set to LOW or HIGH mode. Hold
one washer in each hand using your thumb and
index finger. The speaker sounds as the LED
flashes. Now squeeze the washers harder, the
frequency should increase. This simulates your
galvanic skin resistance lowering due to stress. The
kit is ready for use. Ask the person holding the
washers questions and see if they are telling the
truth.
You can also use the kit as a moisture indicator for
plants. Remove the washers and strip ends of the
two wires 1". Insert the wires into the soil, the more
moisture in the soil the faster the circuit oscillates.