Elenco Electronics K-43 User guide

DECISION MAKER KIT
MODEL K-43
Assembly and Instruction Manual
Elenco Electronics, Inc.
Copyright © 2002 Elenco Electronics, Inc. 753123

PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this Decision Maker 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 #
2 R1, R8 470W5% 1/4W yellow-violet-brown-gold 134700
1 R5 15kW5% 1/4W brown-green-orange-gold 151500
1 R2 56kW5% 1/4W green-blue-orange-gold 155600
1 R7 68kW5% 1/4W blue-gray-orange-gold 156800
1 R3 100kW5% 1/4W brown-black-yellow-gold 161000
1 R4, R6 1.5MW5% 1/4W brown-green-green-gold 171500
CAPACITORS
Qty. Symbol Value Description Part #
1 C1 .0039mF (392) Mylar 233917
1 C2 .015mF (153) Mylar 241517
1 C3 2.2mF 50V Electrolytic (Lytic) 262247
1 C4 47mF 16V Electrolytic (Lytic) 274744
SEMICONDUCTORS
Qty. Symbol Value Description Part #
1 D1 1N4148 Diode 314148
1 Q1 2N3904 Transistor 323904
1 U1 4011 Integrated Circuit (IC) 334011
1 U2 4017 Integrated Circuit (IC) 334017
8 LED 1 - 8 Light Emitting Diode (LED) 350001
MISCELLANEOUS
-1-
Resistor Capacitors
PARTS IDENTIFICATION
Electrolytic
Switch
Diode
Battery Snap
Buzzer
Qty. Description Part #
1 PC Board 517017
1 Dimple Switch 546101
1 Battery Snap 590098
1 Buzzer Piezoelectric 595201
1 Filter Red 621400
1 Spacer 7/32” 624008
Qty. Description Part #
1 Tape 2-sided 1” 748127
1 Cushion Tape 1” 790006
1 Wire Red 22ga. 1” 814220
1 Wire Bare 24ga. 1” 835000
1 Solder Tube 9ST4
Mylar Dimple
Integrated Circuit
IC Socket
LED Transistor

-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 +0.5%
Blue +0.25%
Violet +0.1%
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 0.01 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-
INTRODUCTION
Need help in making up your mind? Just ask the
K-43 Decision Maker. Press the ask button and the
right answer will be given to your question. The
Decision Maker has eight light emitting diodes
(LEDs) that are driven ON and OFF one at a time
in sequence. When the ASK button is pushed, the
LEDs will flash and the buzzer will sound. After a
brief period of time, only one LED will remain lit.
Next to the lit LED is the answer to the question
asked. In a minute or two the LED will get dim and
gradually go out.
Figure 1 shows the block diagram of the Decision
Maker circuit. It consists of two oscillators and eight
LEDs driven by a decade counter. One oscillator
drives the decade counter and the oscillators are
controlled by two timers. We shall proceed to study
the circuit in detail.
THEORY OF OPERATION
OSC 1
Decade
Counter
Timer 2
OSC 2
Timer 1
Buzzer
LEDs
PRESS
BUTTON
B+
Figure 1
The Decade Counter
The 4017 IC is a 5 stage divide by 10 counter. Figure
2 shows a diagram of this IC. This IC has 10 outputs
and a clear input. Only one of the 10 outputs will be
high at any given time. The other 9 will be low. Let’s
assume that output 1 is high. If a pulse is fed into the
clock input, output 1 will go low and output 2 will go
high. Each clock pulse will move the output one
position. Connect an LED to the output, it will light
only when the output goes high. It is obvious that
when the clock is running, the LEDs will flash on and
off with the speed of the clock. When the clock stops,
only one LED will be lit.
In this design, 8 LEDs are used per IC, but the
counter has 10 outputs. If the clock stops at an
output without an LED, nothing will light. To prevent
this, the 4017 IC is reset after hitting the 8th output.
This is simply done by tying the 9th output to the
clear pin (pin 9 and pin 15 shorted together).
The Light Emitting Diodes (LED)
The operation of the LED is very simple. When
current flows through the LED, it will emit light. Note
that the LED is connected between an IC output and
ground through a resistor. When the IC output goes
high, the LED will light. The resistor limits the current
so that the LED will not be damaged.
Figure 2
3
2
4
7
10
1
5
6
9
11
12
VDD - Pin 16
VSS - Pin 8
Block Diagram
15
14
1
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
COUT
Clock
Clock
Enable
Reset

-4-
Oscillators
The Decision Maker uses two oscillators. The first
oscillator produces a frequency of about 20 hertz
(cycles) and the other produces a frequency of about
2000 hertz. Figure 3 shows the basic oscillator
circuit. The 4011 integrated circuit (IC) contains four
two-input NAND gates. Two of these NAND gates are
needed to form an oscillator. Feed back for this
oscillator is via capacitor C2 and resistors R4 and R5.
These elements determine the frequency of
oscillation. Both IC1 and IC2 act as inverters, that is,
when the input is low, the output is high. As long as
pin 13 of IC1 is high, the circuit will oscillate. If pin 13
is brought low, the circuit will stop oscillating.
The second oscillator is similar to the one described
except for a difference in its frequency controlling
components, capacitor C1 and resistors R2 and R3.
C1 and R2 are smaller values causing the oscillator
to oscillate at a much higher frequency. Pin 5 of the
first NAND gate is brought high at a 20 cycles rate.
This causes the second oscillation to be chopped up
at the first oscillation frequency rate as shown in
Figure 4. This combination produces the unusual
sound heard from the buzzer.
Buzzer
The Decision Maker buzzer consists of a
piezoelectric material on a metal base. When a
voltage is applied to piezoelectric material, its
dimensions change. The buzzer is connected to the
2kHz oscillator. When the oscillator runs, the
changing dimensions to the piezoelectric buzzer act
like the cone of a speaker to set up sound waves.
Timer
Timer 1 is made up of capacitors C3 and R6. Timer
2 is made up of capacitor C4 and R7 (see Figure 5).
When S1 is pushed, both capacitors charge up to 9
volts and the oscillators run. When the switch is
released, capacitor C3 discharges through resistor
R6 and capacitor C4 discharges through resistor R7
and the base of Q1.
Note that C3 is tied to pin 13 of the 4011 IC. Thus,
when capacitor C3 loses its charge, the circuit stops
oscillating. The buzzer stops and a single LED
remains lit. After a minute or two, C4 loses its charge
and removes the base current from Q1. Q1 is in the
ground return path of the LEDs and both ICs. Thus,
when Q1 is turned off, the LED goes out. Only a very
small leakage current is then drawn from the battery.
This current is so small that no ON/OFF switch is
required.
Figure 4
Figure 3
IC2
R5 R4
C2
+V
Pin 13 IC1
4011 IC
Figure 5

Introduction
The most important factor in assembling your K-43 Decision Maker 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
-5-

Figure G
Mount the mylar capacitor to the PC
board and bend it 90Oas shown. Solder
and cut off the excess leads.
Figure A
Mount the LED
flush to the PC
board with the flat
side of the LED in
the same direction
as marked on the
PC board.
ASSEMBLE COMPONENTS TO THE PC BOARD
R7 - 68kW5% 1/4W Resistor
(blue-gray-orange-gold)
Q1 - 2N3904 Transistor
(see Figure C)
C3 - 2.2mF 50V Electrolytic
(see Figure D)
R6 - 1.5MW5% 1/4W Resistor
(brown-green-green-gold)
C4 - 47mF 16V Electrolytic
(see Figure D)
D1 - 1N4148 Diode
(see Figure E)
JP1 - Jumper Wire
(see Figure F)
C1 - .0039mF (392) Mylar Cap.
(see Figure G)
R2 - 56kW5% 1/4W Resistor
(green-blue-orange-gold)
R1 - 470W5% 1/4W Resistor
(yellow-violet-brown-gold)
R3 - 100kW5% 1/4W Resistor
(brown-black-yellow-gold)
U1 - 4011 Integrated Circuit
(see Figure B)
R5 - 15kW5% 1/4W Resistor
(brown-green-orange-gold)
R4 - 1.5MW5% 1/4W Resistor
(brown-green-green-gold)
C2 - .015mF (153) Mylar Cap.
(see Figure G)
R8 - 470W5% 1/4W Resistor
(yellow-violet-brown-gold)
Figure B
Insert the IC into the PC board
with the notch in the same
direction as marked on the PC
board.
Figure F
Form a discarded piece of a capacitor lead long
enough so 1/4” of wire passes through each hole in
the PC board. Mount the wire down close.
Figure E
Diodes have polarity.
Mount them with the
band in the correct
direction, as shown on
the PC board.
-6-
Band
Flat
Notch
Figure C
Mount the transistor with the flat
side in the same direction marked
on the PC board. Leave about
1/16” space between the PC board
and the transistor.
Flat
Figure D
Electrolytic capacitors have polarity. Be
sure to mount them with the negative (–)
lead (marked on side) in the correct hole.
Mount the electrolytics horizontal to the
PC board. Bend the leads at right angles
and then insert the leads into the PC
board.
J3 & J4 - Battery Snap
Install the red wire into the positive (+) hole
and the black wire into the negative (–)
hole as shown. Bend the leads to hold the
battery snap in place. Solder and cut off
the excess leads.
LED 5 - Light Emitting Diode
(see Figure A)
LED 4 - Light Emitting Diode
(see Figure A)
LED 8 - Light Emitting Diode
(see Figure A)
LED 7 - Light Emitting Diode
(see Figure A)
LED 3 - Light Emitting Diode
(see Figure A)
U2 - 4017 Integrated Circuit
(see Figure B)
LED 1 - Light Emitting Diode
(see Figure A)
LED 2 - Light Emitting Diode
(see Figure A)
LED 6 - Light Emitting Diode
(see Figure A)
Polarity
Marking
Red
Black

-7-
Figure I
S1, S2
Solder the 1” 24 ga. bare wire to S1 and S2 as shown.
Cut the wire so that each end extends 1/16” above the PC
board. Then, bend the wires toward each other and also
press them flat against the PC board with your pliers.
Place the dimple switch with the dome upward over the
S1 and S2 wires. Hold the switch in place with the
double-sided tape. Mount the spacer on top of the switch,
the double-sided tape on the switch will hold it in place.
ASSEMBLE COMPONENTS TO THE PC BOARD (CONTINUED)
Dimple
Switch
Tape
Cut the cushion tape into four equal 1/4” sections.
Peel off the protective film on one side of the
cushion tape and stick a section of tape on each
corner of the PC board on the top legend side
(see Figure J).
Place the spacer over the dimple switch as shown in
Figure J. Peel off the protective film on the other side
of the cushion tape and stick the red filter in place so
that the “ASK” ellipse is directly over the spacer on
the switch (see Figure J).
Spacer
1/4” Cushion Tape
1/4” Cushion Tape
Red Filter
PC Board
Figure J
Figure H
Buzzer
Mount the buzzer on the foil side of the PC board. The
white center should be facing up, also note the position
of the pad in the white area. Solder the buzzer to the PC
board at the two points. Strip the insulation off of both
ends of the red wire to expose 1/8” of bare wire. Solder
the wire to the buzzer and PC board.
BZ1
Solder Points

TROUBLESHOOTING
Contact Elenco Electronics if you have any problems. DO NOT contact your place of purchase as they will not
be able to help you.
-8-
OPERATING PROCEDURE
1. One of the most frequently occurring problems is
poor solder connections.
a) Tug slightly on all parts to make sure that they
are indeed soldered.
b) All solder connections should be shiny.
Resolder any that are not.
c) Solder should flow into a smooth puddle
rather than a round ball. Resolder any
connection that has formed into a ball.
d)
Have any solder bridges formed? A solder
bridge may occur if you accidentally touch an
adjacent foil by using too much solder or by
dragging the soldering iron across adjacent
foils. Break the bridge with your soldering iron.
2. Be sure that all components have been mounted
in their correct places.
a) The LEDs will not light if they have not been
installed correctly. The flat side of the LEDs
should be in the same direction as marked on
the PC board.
b) Be sure capacitors C3 and C4 are installed
correctly. These capacitors are polarized so
be sure that the positive and negative leads
are in the correct hole as marked on the PC
board.
c) Be sure that ICs U1 and U2 are installed
correctly. The notch should be in the direction
shown on the PC board.
d) Be sure that transistor Q1 has been installed
correctly. The flat side of the transistor should
be in the same direction as marked on the PC
board.
e) Be sure that diode D1 is installed correctly.
The stripe on the diode should be on the
same side as the stripe marked on the PC
board.
3. Use a fresh 9 volt ALKALINE battery.
4. NO SOUND AND NO LEDs
a) Check that the battery snap is wired as
shown on page 6 of this manual. The black
wire goes to J4 (–) and the red wire goes to
J3 (+).
b) Check that U1 and U2 are not installed
backwards. Be sure that there are no solder
bridges between the IC pins.
c) Check that the dimple switch is mounted with
the dome upward.
d) Check the value and the soldering of R7.
e) Check Q1.
5. CONTINUOUS SOUND AND LED
a) Check the wires in S1 and S2. They should
make contact with the dimple switch only
when the “ASK” ellipse on the red filter is
pressed.
6. LEDs BUT NO SOUND
a) Check that the buzzer is soldered as shown
in Figure H on page 7. Check the solder
connection between the jumper wire and the
center pad of the buzzer.
b) Check for soldering bridges between the pins
of U1.
c) Check the value and the soldering of R1, R2,
and R3.
7. LEDs STOP AS SOON AS THE SWITCH IS
RELEASED
a) Check that C3 and C4 are mounted with the
negative (–) lead in the hole marked on the
PC board.
b) Check the value and soldering of R6.
c) Check D1.
Operating your Decision Maker is very simple. Just
connect a 9 volt alkaline battery to the battery snap
and you are ready to go. Push the ASK button to get
your decision!

-9-
QUIZ
Fill in the blanks and check your answers below.
Answers: 1. off; 2. decade counter; 3. five, ten; 4. two; 5. NAND; 6. dimension; 7. oscillators; 8. C4
1. When driven by clock pulses, the outputs of the
decade counter will go on and _____________
one at a time in sequence.
2. LEDs are driven by a _____________
_____________.
3. The 4017 IC contains a _________ stage divide
by _____________ counter.
4. The Decision Maker uses _________ oscillators.
5. The 4011 IC contains four two-input __________
gates.
6. When a voltage is applied to the piezoelectric
buzzer, it changes its _____________.
7. When the ASK button is pushed, capacitors C3
and C4 charge up to 9V, and the
_____________ start running.
8. After the oscillators stop, only one LED will
remain lit and then gradually fade out as
_____________ loses its charge.