Elenco Electronics SNAP CIRCUITS XP SCXP-50 User manual

Copyright © 2013 by ELENCO®Electronics, Inc. All rights reserved. No part of this book shall be reproduced by 753154
any means; electronic, photocopying, or otherwise without written permission from the publisher.
REV-A
Patent #‘s: 7,144,255, 7,273,377, & other patents pending
Project A3

-1-
WARNING: SHOCK HAZARD - Never connect Snap
Circuits®to the electrical outlets in your home in any way!
WARNING: CHOKING HAZARD - Small
parts. Not for children under 3 years.
!
Conforms to all
applicable U. S.
government standards.
1. Most circuit problems are due to incorrect
assembly, always double-check that your
circuit exactly matches the drawing for it.
2. Be sure that parts with positive/negative
markings are positioned as per the drawing.
3. Be sure that all connections are securely
snapped.
4. Try replacing the batteries.
5. If the motor spins but does not balance the
fan, check the black plastic piece with three
prongs on the motor shaft.
ELENCO®is not responsible for parts damaged
due to incorrect wiring.
Basic Troubleshooting
Note: If you suspect you have damaged parts, you
can follow the Advanced Troubleshooting procedure on
page 8 to determine which ones need replacing.
Basic Troubleshooting 1
Parts List 2
About Your Snap Circuits®Parts 3 - 5
Introduction to Electricity 6
DO’s and DON’Ts of Building Circuits 7
Advanced Troubleshooting 8
Project Listings 9
How to Use Snap Circuits® 10
Part A – Introductory Projects (A1-A30) 11 - 27
Part B – Microcontroller Projects (B1-B27) 28 - 58
Part C – To Go Further 59
Other Snap Circuits®Products 62
Table of Contents
WARNING: Always check your wiring before
turning on a circuit. Never leave a circuit
unattended while the batteries are installed.
Never connect additional batteries or any
other power sources to your circuits. Discard
any cracked or broken parts.
Adult Supervision: Because children’s
abilities vary so much, even with age groups,
adults should exercise discretion as to which
experiments are suitable and safe (the
instructions should enable supervising
adults to establish the experiment’s
suitability for the child). Make sure your child
reads and follows all of the relevant
instructions and safety procedures, and
keeps them at hand for reference.
This product is intended for use by adults
and children who have attained sufficient
maturity to read and follow directions and
warnings.
Never modify your parts, as doing so may
disable important safety features in them, and
could put your child at risk of injury.
• Use only 1.5V “AA” type, alkaline batteries (not
included).
• Insert batteries with correct polarity.
• Non-rechargeable batteries should not be
recharged. Rechargeable batteries should only
be charged under adult supervision, and should
not be recharged while in the product.
• Do not connect batteries or battery holders in
parallel.
• Do not mix old and new batteries.
• Do not mix alkaline, standard (carbon-zinc), or
rechargeable (nickel-cadmium) batteries.
• Remove batteries when they are used up.
• Do not short circuit the battery terminals.
• Never throw batteries in a fire or attempt to open
its outer casing.
• Batteries are harmful if swallowed, so keep away
from small children.
Batteries:
!
WARNING TO ALL PROJECTS WITH A SYMBOL - Moving parts. Do not touch the motor or fan during operation. Do not
lean over the motor. Do not launch the fan at people, animals, or objects. Eye protection is recommended.
!!
!
Requirements for your computer: Windows®
XP (or later) or Mac OS X 10.2 (or later) or Linux,
512MB RAM, 500MB of hard-disk space, USB
port, and an internet connection.

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Important: If any parts are missing or damaged, DO NOT RETURN TO RETAILER. Call toll-free [phone] or e-mail us at:
[email protected]. Customer Service • 150 Carpenter Ave. • Wheeling, IL 60090 U.S.A.
Parts List (Colors and styles may vary) Symbols and Numbers
Qty. ID Name Symbol Part # Qty. ID Name Symbol Part #
r1Base Grid
(11.0” x 7.7”) 6SCBG r1Fan Blade 6SCM1F
r61-Snap Wire 6SC01 r2NPN Transistor 6SCQ2
r92-Snap Wire 6SC02 r1100WResistor 6SCR1
r43-Snap Wire 6SC03 r21kWResistor 6SCR2
r34-Snap Wire 6SC04 r210kWResistor 6SCR4
r15-Snap Wire 6SC05 r1100kWResistor 6SCR5
r16-Snap Wire 6SC06 r1Photoresistor 6SCRP
r17-Snap Wire 6SC07 r1Adjustable Resistor 6SCRV
r1Battery Holder - uses
3 1.5V type AA (not Included)
6SCB3 r1Slide Switch 6SCS1
r1470mF Capacitor 6SCC5 r1Press Switch 6SCS2
r1Red Light Emitting
Diode (LED) 6SCD1 r18 Ohm Speaker 6SCSP
r1Green Light Emitting
Diode (LED) 6SCD2 r1Microcontroller IC 6SCU21
r1Jumper Wire (Black) 6SCJ1 r1Microphone 6SCX1
r1Jumper Wire (Red) 6SCJ2 r1Programming Cable 9TLSCXP
r1DC Motor 6SCM1
You may order additional / replacement parts at our website: www.snapcircuits.net
5
4
3
2
1
RP
U21
S2
R2
X1
B3
D1
C5
D2
R1
SP
6
7
M1
Q2
R5
R4
RV
S1

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About Your Snap Circuits®XP Parts
(Part designs are subject to change without
notice).
BASE GRID
SNAP WIRES & JUMPER WIRES
MOTOR
Magnet
Electromagnet
Shaft
Power Contacts
Shell
Motor (M1)
BATTERY HOLDER
Battery Holder (B3)
The batteries (B3) produce an electrical voltage
using a chemical reaction. This “voltage” can be
thought of as electrical pressure, pushing
electricity through a circuit just like a pump
pushes water through pipes. This voltage is
much lower and much safer than that used in
your house wiring. Using more batteries
increases the “pressure”, therefore, more
electricity flows.
The blue snap wires
are wires used to
connect components.
They are used to
transport electricity and do
not affect circuit performance.
They come in different lengths to
allow orderly arrangement of connections
on the base grid.
The red and black
jumper wires make
flexible connections for
times when using the snap wires
would be difficult. They also are
used to make connections off the base grid.
Wires transport electricity just like pipes are used
to transport water. The colorful plastic coating
protects them and prevents electricity from
getting in or out.
The base grid is a platform for
mounting parts and wires.
It functions like the
printed circuit
boards used in
most electronic
products, or like how
the walls are used for
mounting the electrical
wiring in your home.
The motor (M1) converts electricity into
mechanical motion. An electric current in the
motor will turn the shaft and the motor blades,
and the fan blade if it is on
the motor.
Fan
How does electricity turn the shaft in the motor?
The answer is magnetism. Electricity is closely
related to magnetism, and an electric current
flowing in a wire has a magnetic field similar to
that of a very, very tiny magnet. Inside the motor
is a coil of wire with many loops wrapped around
metal plates. This is called an electromagnet. If
a large electric current flows through the loops,
it will turn ordinary metal into a magnet. The
motor shell also has a magnet on it. When
electricity flows through the electromagnet, it
repels from the magnet on the motor shell and
the shaft spins. If the fan is on the motor shaft,
then its blades will create airflow.

-4-
About Your Snap Circuits®XP Parts
RESISTORS
MICROPHONE
SPEAKER
SLIDE & PRESS SWITCHES RED & GREEN LEDs
CAPACITOR
Resistors (R1, R2, R4, & R5)
Resistors “resist” the flow of electricity and are
used to control or limit the current in a circuit.
Snap Circuits®XP includes 100W(R1), 1kW(R2),
10kW(R4), and 100kW(R5) resistors (“K”
symbolizes 1,000, so R4 is really 10,000W).
Materials like metal have very low resistance
(<1W), while materials like paper, plastic, and air
have near-infinite resistance. Increasing circuit
resistance reduces the flow of electricity.
The slide & press switches (S1 & S2) connect
(pressed or “ON”) or disconnect (not pressed or
“OFF”) the wires in a circuit. When ON they have no
effect on circuit performance. Switches turn on
electricity just like a faucet turns on water from a pipe.
Slide & Press Switches (S1 & S2)
The speaker (SP) converts electricity into sound
by making mechanical
vibrations. These vibrations
create variations in air
pressure, which travel
across the room. You
“hear” sound when your
ears feel these air
pressure variations.
Speaker (SP)
The microphone (X1) is actually a resistor that
changes in value when changes in air pressure
(sounds) apply pressure to its surface. Its
resistance typically varies from around 1kWin
silence to around 10kWwhen you blow on it
Microphone (X1)
The photoresistor (RP) is a light-sensitive
resistor, its value changes from nearly infinite in
total darkness to about 1000Wwhen a bright light
shines on it.
Photoresistor (RP)
The adjustable resistor (RV) is a 50kWresistor
but with a center tap that can be adjusted
between 200Wand 50kW.
Adjustable Resistor (RV)
The 470mF capacitor (C5) can store electrical
pressure (voltage) for periods of time. This
storage ability allows it to block stable voltage
signals and pass changing ones. Capacitors are
used for filtering and delay circuits.
Capacitor (C5)
The red & green LED’s (D1 & D2) are light
emitting diodes, and may be thought of as a
special one-way light bulb. In the “forward”
direction, (indicated by the “arrow” in the symbol)
electricity flows if the voltage exceeds a turn-on
threshold (about 1.5V for red and a little higher
for green); brightness then increases. A high
current will burn out the LED, so the current must
be limited by other components in the circuit.
LED’s block electricity in the “reverse” direction.
LED’s (D1 & D2)

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About Your Snap Circuits®XPTM Parts
The NPN (Q2) transistors are components that
use a small electric current to control a large
current, and are used in switching, amplifier, and
buffering applications. They are easy to
miniaturize, and are the main
building blocks of
integrated circuits
including the
microprocessor and
memory circuits in
computers.
TRANSISTORS
U21 Microcontroller IC:
(+) - power from batteries
(GND) - power return to batteries
S-In - Programming input snap
S-Out /Snap 0 - Serial Output 0
Snap 1 - IN1/OUT1/ADC1
Snap 2 - IN2/OUT2/ADC2
Snap 3 - IN3
Snap 4 -IN4/OUT4/ADC4
Note: There is additional information for
the PICAXE®08M2 integrated circuit at
www.picaxe.co.uk.
The programming cable is used to program and
communicate with the U21 microcontroller.
CABLES
MICROCONTROLLER
Microcontroller outputs cannot control the motor
or speaker directly, an interface transistor must
be used. Microcontroller outputs can control Snap
Circuits®LEDs directly.
Programming Cable
NPN Transistor (Q2)
The microcontroller IC (U21) includes the
PICAXE®08M2 integrated circuit. This is a mini
computer which can be programmed to perform
different tasks, including monitoring things and
making things happen. The PICAXE®08M2 has
a special programming interface that makes it
very easy to use.
Microcontroller IC (U21)
Notes for using the PICAXE®-08M2 in
other applications:
Power source:
This should be 4.5V or 5V. Higher voltages
may damage the part.
S-In connection:
The U21 platform has an internal 10KW
resistor between the S-In and GND snaps,
and a 22KWresistor between the S-In snap
and the microcontroller. These facilitate use of
the programing cable.
Several snaps can be used as either
inputs, outputs, or analog to digital
converters:
as Outputs: Each output can supply or
receive up to 20 mA. This is enough to light an
LED, but an interface transistor must be used
when controlling a motor or speaker.
as Inputs: An input should be above 80% of
the power source voltage to be high, or below
20% of the power source voltage to be low.
as Analog to Digital Converters (ADC): The
ADC range is the power source voltage range.
Circuit resistance should be less than 20KW,
or false readings may occur.

Introduction to Electricity
What is electricity? Nobody really knows. We only know how to produce it,
understand its properties, and how to control it. Electricity is the movement
of sub-atomic charged particles (called electrons) through a material due
to electrical pressure across the material, such as from a battery.
Power sources, such as batteries, push electricity through a circuit, like a
pump pushes water through pipes. Wires carry electricity, like pipes carry
water. Devices like LEDs, motors, and speakers use the energy in
electricity to do things. Switches and transistors control the flow of
electricity like valves and faucets control water. Resistors limit the flow of
electricity.
The electrical pressure exerted by a battery or other power source is called
voltage and is measured in volts (V). Notice the “+” and “–” signs on the
battery; these indicate which direction the battery will “pump” the electricity.
The electric current is a measure of how fast electricity is flowing in a
wire, just as the water current describes how fast water is flowing in a pipe.
It is expressed in amperes (A) or milliamps (mA, 1/1000 of an ampere).
The “power” of electricity is a measure of how fast energy is moving
through a wire. It is a combination of the voltage and current (Power =
Voltage x Current). It is expressed in watts (W).
The resistance of a component or circuit represents how much it resists
the electrical pressure (voltage) and limits the flow of electric current. The
relationship is Voltage = Current x Resistance. When the resistance
increases, less current flows. Resistance is measured in ohms (W), or kilo
ohms (kW, 1000 ohms).
Nearly all of the electricity used in our world is produced at enormous
generators driven by steam or water pressure. Wires are used to efficiently
transport this energy to homes and businesses where it is used. Motors
convert the electricity back into mechanical form to drive machinery and
appliances. The most important aspect of electricity in our society is that it
allows energy to be easily transported over distances.
Note that “distances” includes not just large distances but also tiny
distances. Try to imagine a plumbing structure of the same complexity as
the circuitry inside a portable radio - it would have to be large because we
can’t make water pipes so small. Electricity allows complex designs to be
made very small.
There are two ways of arranging parts in a circuit, in
series or in parallel. Here are examples:
Placing components in series increases the resistance;
highest value dominates. Placing components in parallel
decreases the resistance; lower value dominates.
The parts within these series and parallel sub-circuits
may be arranged in different ways without changing what
the circuit does. Large circuits are made of combinations
of smaller series and parallel circuits.
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Series Circuit
Parallel Circuit

-7-
DO’s and DON’Ts of Building Circuits
After building the circuits given in this booklet, you may wish to experiment on your own.
Use the projects in this booklet as a guide, as many important design concepts are
introduced throughout them. Every circuit will include a power source (the batteries), a
resistance (which might be a resistor, capacitor, motor, integrated circuit, etc.), and wiring
paths between them and back. You must be careful not to create “short circuits” (very low-
resistance paths across the batteries, see examples at right) as this will damage
components and/or quickly drain your batteries. Only connect the U21 microcontroller IC
(the PICAXE 08M) using configurations given in the projects, incorrectly doing so may
damage it. ELENCO®is not responsible for parts damaged due to incorrect wiring.
Here are some important guidelines:
ALWAYS USE EYE PROTECTION WHEN EXPERIMENTING ON YOUR OWN.
ALWAYS include at least one component that will limit the current through a circuit, such
as the speaker, capacitors, ICs (which must be connected properly), motor,
microphone, photoresistor, or resistors.
ALWAYS use LEDs, transistors, and switches in conjunction with other components that
will limit the current through them. Failure to do so will create a short circuit
and/or damage those parts.
ALWAYS connect capacitors so that the “+” side gets the higher voltage.
ALWAYS disconnect your batteries immediately and check your wiring if something
appears to be getting hot.
ALWAYS check your wiring before turning on a circuit.
ALWAYS connect U21 microcontroller IC using configurations given in the projects or
as per the connection description on page 5.
NEVER connect to an electrical outlet in your home in any way.
NEVER touch the motor when it is spinning at high speed.
Placing a 3-snap wire directly
across the batteries is a
SHORT CIRCUIT.
This is also a
SHORT CIRCUIT.
When the slide switch (S1) is turned on, this large circuit has a SHORT
CIRCUIT path (as shown by the arrows). The short circuit prevents any
other portions of the circuit from ever working.
NEVER
DO!
NEVER
DO!
NEVER
DO! NEVER
DO!
Examples of SHORT CIRCUITS - NEVER DO THESE!!!
Warning to Snap Circuits®owners: Do not use
parts from other Snap Circuits®sets with this kit. Other
sets use higher voltage which could damage the
microcontroller and other parts.
You are encouraged to tell us about new programs and circuits you
create. If they are unique, we will post them with your name and state
on our website at www.snapcircuits.net/kidkreations.htm. Send
your suggestions to ELENCO®: [email protected].
ELENCO®provides a circuit designer so that you can make your own
Snap Circuits®drawings. This Microsoft®Word document can be
downloaded from www.snapcircuits.net/SnapDesigner.doc or
through the www.snapcircuits.net website.
WARNING: SHOCK HAZARD - Never connect Snap Circuits®
to the electrical outlets in your home in any way!
!
!
!
!
!

Advanced Troubleshooting (Adult supervision recommended)
-8-
ELENCO®
150 Carpenter Avenue
Wheeling, IL 60090 U.S.A.
Phone: [phone]
Fax: [phone]
e-mail: [email protected]
Website: www.elenco.com
You may order additional /
replacement parts at:
www.snapcircuits.net
ELENCO®is not responsible for parts
damaged due to incorrect wiring.
If you suspect you have damaged parts,
you can follow this procedure to
systematically determine which ones need
replacing:
(Note: Some of these tests connect an LED
directly across the batteries without another
component to limit the current. Normally this
might damage the LED, however Snap Circuits®
LEDs have internal resistors added to protect
them incorrect wiring, and will not be damaged.)
1. LEDs (D1 & D2), motor (M1), speaker
(SP), and battery holder (B3): Place
batteries in holder. Place one of the LEDs
directly across the battery holder (LED + to
battery +), it should light. Do the same for
the motor, it should spin. “Tap” the speaker
across the battery holder contacts, you
should hear static as it touches. If none
work, then replace your batteries and
repeat. If still bad, then the battery holder is
damaged.
2. Jumper wires:
Use this mini-
circuit to test
each jumper
wire, the LED
should light.
3. Snap wires: Use this mini-circuit to test
each of the snap wires, one at a time. The
LED should light.
4. Slide switch (S1) and Press switch (S2):
Use this mini-circuit; if the LED doesn’t light
then the slide
switch is bad.
Replace the
slide switch
with the press
switch to test it.
5. 100W(R1), 1kW(R2), and 10kW(R4)
resistors: Use the mini-circuit from test 4
but replace the switch with the 100Wresistor
(R1); the LED will be bright if the resistor is
good. Next use the 1kWand 10kWresistors
in place of the 100Wresistor; the LED
should be dimmer but still light.
6. Microphone (X1) and Photoresistor (RP):
Use the mini-circuit from test 4 but replace
the switch with the microphone (X1, + on
right); if blowing into the microphone does
not change the LED brightness then the
microphone is bad. Replace the microphone
with the photoresistor. Waving your hand
over the photoresistor (changing the light
that shines on it) should change the
brightness of the LED or the photoresistor is
bad.
7. Adjustable resistor (RV): Build Project
#A16, the resistor control lever should turn
the LED (D1) on and off; otherwise it is bad.
8. NPN transistor (Q2): Build the mini-circuit
shown here. The LED (D2) should only be
on if the press switch (S2) is pressed. If
otherwise, then the NPN is damaged.
9. 470mF capacitor (C5) and 100kW
resistor (R5): Build the mini-circuit shown
here. When you press the switch, the LED
should be bright but then slowly get dim,
otherwise the
capacitor is bad.
Replace the 1kW
resistor (R2)
with the 100kW
resistor (R5); the
LED should stay
on much longer
or R5 is bad.
10. Programming cable: Connect the cable
to the red LED (D1), orange and yellow
wires to (+) and black wire to the other
side. Run the AXEpad for Snap Circuits®
XP software. Open a terminal (press F8).
Type something into the output buffer and
press Send. The red LED should flash and
what you typed should appear in the input
buffer.
11. Microcontroller (U21): Use project B27
(Test the Microcontroller).

Project Listings
Part A - Introductory Projects: These projects introduce you to the
Snap Circuits®method of building circuits and show how electronic
components work. No computer is needed for these projects (some
projects use the U21 microcontroller, but with a factory-loaded program).
Part B - Microcontroller Projects: These projects are an
introduction to microprocessors, and the flexibility they give by being
programmable. A computer is needed to load programs into the
microcontroller, but no other programming knowledge is needed. The
microcontroller re-programming procedure is explained in project B1.
Part C - To Go Further: This section is intended for users who
would like to develop their own programs for the microcontroller. It
also has bonus circuits for owners of other Snap Circuits®models.
-9-
Project # Title Page #
A1 Electric Light 11
A2 Controlling Electricity 11
A3 Dancing Motor 12
A4 Electronic Counter 13
A5 Adding Sound to the Counter 14
A6 Daylight Alarm Clock 14
A7 Intruder Alarm 15
A8 Jukebox 16
A9 Counting to the Stars 17
A10 Angles and Distance 18
A11 Flip-Flop 19
A12 Adjustable Light Timer 19
A13 Light Sensitive Timer 20
A14 Shot in the Dark 20
A15 Microphone Control 21
A16 Adjustable Brightness 21
A17 Conduction Detector 21
A18 Slider 22
A19 Parallel Resistors 22
A20 Series Resistors 22
A21 Flying Saucer 23
A22 Transistor 23
A23 Capacitor Battery 24
A24 Blow Off Sound 24
A25 Capacitor Photo Control 25
A26 Capacitor Photo Control with Slow Shut-off 25
A27 Photo Switcher 26
A28 Blow On Sound 26
A29 Scratchy Amplifier 27
Project # Title Page #
A30 One Shot 27
B1 Blinker (Programming the Microcontroller) 29
B2 Blinkers 33
B3 Four Outputs 34
B4 Play a Tune 35
B5 Computer Music Box 36
B6 Random Sounds 38
B7 Sloppy Switches 39
B8 Bounceless Switches 40
B9 Jukebox with Terminal 41
B10 Launch Pad 42
B11 Adjustable Blinker 43
B12 Basic Light Meter 44
B13 Capacitor Discharge 45
B14 Sunrise Alarm 46
B15 Photon Counter 47
B16 Photon Kazoo 47
B17 Click Counter 48
B18 Super Click Counter 49
B19 Data Logger 50
B20 Data Logger with Cost 51
B21 24 Hour Data Logger 52
B22 Digital Voltmeter 53
B23 Battery Tester (4V or less) 54
B24 Battery Tester (20V or less) 55
B25 Clap Light 56
B26 Clap Music 57
B27 Test the Microcontroller 58

How to Use Snap Circuits
®
Snap Circuits®uses building blocks with snaps
to build the different electrical and electronic
circuits in the projects. Each block has a
function: there are switch blocks, light blocks,
battery blocks, different length wire blocks, etc.
These blocks are different colors and have
numbers on them so that you can easily
identify them. The blocks you will be using are
shown as color symbols with level numbers
next to them, allowing you to easily snap them
together to form a circuit.
For Example:
This is the switch block which is green and has
the marking on it. The part symbols in this
booklet may not exactly match the appearance
of the actual parts, but will clearly identify them.
This is a wire block which is blue and comes
in different wire lengths.
This one has the number , , , , ,
or on it depending on the length of the wire
connection required.
There is also a 1-snap wire that is used as a
spacer or for interconnection between different
layers.
You need a power source to build each circuit.
This is labeled and requires three (3) “AA”
batteries (not included).
A large clear plastic base grid is included with
this kit to help keep the circuit blocks properly
spaced. You will see evenly spaced posts that
the different blocks snap into. The base has
rows labeled A-G and columns labeled 1-10.
Next to each part in every circuit drawing is a
small number in black. This tells you which
level the component is placed at. Place all
parts on level 1 first, then all of the parts on
level 2, then all of the parts on level 3, etc.
Some circuits use the jumper wires to make
unusual connections. Just clip them to the
metal snaps or as indicated.
Usually when the motor is used, the fan will
be placed on it.
No computer is needed for introductory
projects (some projects use the U21
microcontroller, but with a factory-loaded
program).
Occasionally you may feel static electricity if
you touch a circuit when the programming
cable is connected, usually when humidity is
very low. Don’t worry; this is harmless. It
occurs because the cable makes an easy
electrical path between your body and the
ground, allowing static that has built up on you
to dissipate. Sometimes this static electricity
may reset the microcontroller (U21), causing it
to re-start its program.
Note: While building the projects, be
careful not to accidentally make a direct
connection across the battery holder (a
“short circuit”), as this may damage and/or
quickly drain the batteries.
S2
23 4 5 6
B3
-10-
PART A - Introductory Projects
7
M1

-11-
Project A1 Electric Light
Snap Circuits®uses electronic blocks that snap onto a clear plastic
grid to build different circuits. These blocks have different colors
and numbers on them so that you can easily identify them.
Build the circuit shown on the left by placing all the parts with a
black 1 next to them on the board first. Then, assemble parts
marked with a 2. Install three (3) “AA” batteries (not included) into
the battery holder (B3) if you have not done so already.
When you turn on the slide switch (S1), current flows from the
batteries through the switch, red LED (D1), and 100Wresistor (R1),
and back to the batteries. Turning on the switch completes the
circuit. When the switch is off, the current can no longer flow back
to the battery, so the red LED goes out.
The red LED is just like the ones used in electronic products
throughout your home.
+
Placement Level
Numbers
+
Use the circuit built in project A1, but replace the
100Wresistor (R1) with the 1kWresistor (R2). The
circuit works the same, but the red LED (D1) will
not be as bright.
Now replace the 1kWresistor with the 10kW
resistor (R4). The LED will be dim now.
Now replace the 10kWresistor (R4) with the 100kW
resistor (R5). The 100kWhas very high resistance,
so you may not see any light from the LED.
Take the circuit into a really dark room or curl your
fingers around the LED to block the surrounding
light. Now you see that the LED is on, though very
dim.
Project A2 Controlling Electricity
Snappy says resistors are used to control or
limit the flow of electricity in a circuit. Higher
resistor values reduce the flow of electricity in a
circuit.
In this circuit, the resistors are used to adjust the
LED brightness, to limit the current so the
batteries last longer, and to protect the LED
from being damaged by the batteries.
What is Resistance? Take your hands and rub
them together very fast. Your hands should feel
warm. The friction between your hands converts
your effort into heat. Resistance is the electrical
friction between an electric current and the
material it is flowing through.

Note: This circuit requires program Electronic Brain
to be in microcontroller U21’s memory. This is loaded
into U21 at the Snap Circuits®factory and should still
be there, unless you already reprogrammed it. If it has
been reprogrammed, you must use project B1 (on
page 29) to load program Electronic Brain back into
U21 before building this circuit.
Snap Circuits®uses electronic blocks that snap onto
a clear plastic grid to build different circuits. These
blocks have different colors and numbers on them so
that you can easily identify them.
Build the circuit shown above by placing all the parts
with a black 1 next to them on the board first. Then,
assemble parts marked with a 2. Then, assemble
parts marked with a 3. Install three (3) “AA” batteries
(not included) into the battery holder (B3) if you have
not done so already.
Turn on slide switch (S1) and wait for the red LED
(D1) to come on. Push the press switch (S2) and hold
it down until music starts. Set the lever on the
adjustable resistor (RV) for best sound. The motor
(M1) will spin while you push S2, and then will follow
the music as it plays. The red & green LEDs (D1 &
D2) will blink in time with the music. The fan blade is
not necessary and may be removed.
To change the song, push and release S2, then push
it again but hold it down until music starts. For more
songs, turn S1 off and on, slowly push and release
S2 four times, then push and hold down S2 until
music starts.
If you flip the motor around then the fan will rise into
the air like a flying saucer.
Project A3 Dancing Motor
Placement Level
Numbers
-12-
+
!
WARNING: Moving parts.
Do not touch the fan or
motor during operation. Do
not lean over the motor.
+
This complex circuit is pictured on the front
cover, use that as a guide to help build it.
The program in the microcontroller IC (U21)
controls power to the motor (M1), flashes the
LED (D2), and sends music to the speaker
(SP). The microcontroller is like an electronic
brain running the circuit.
+

Project A4 Electronic Counter
Note: This circuit requires
program Electronic Brain to be in
microcontroller U21’s memory.
This is loaded into U21 at the
Snap Circuits®factory and should
still be there, unless you already
reprogrammed it. If it has been
reprogrammed, you must use
project B1 (on page 29) to load
program Electronic Brain back into
U21 before building this circuit.
The circuit will count how many
times you press switch S2, then
announce the answer by flashing
LEDs.
Turn on slide switch (S1) and
wait a moment for the green LED
(D2) to come on. Slowly press
switch S2 up to 255 times; the
red LED (D1) flashes each time.
Then wait 10 seconds.
After 10 seconds, the
microcontroller (U21) recog-
nizes that it is time to display the
count. The green LED will turn
off, and then the green & red
LEDs will flash based on the
number of S2 presses. The
green LED will flash first and
each flash counts as 4, then the
red LED will flash and each flash
counts as 1.
For example, if you pressed S2
14 times, the green LED will
flash 3 times (representing 12,
since each counts as 4) and the
red LED will flash 2 times (12 + 2
= 14).
When the microcontroller
finishes displaying the count, the
green LED will stay on, indicating
the microcontroller is ready for
you to press S2 more.
The total is cumulative, and so
includes earlier presses in
counting mode. Turn slide switch
S1 off and on to reset the count
to zero.
When pressing S2 to count, do
not press it rapidly on and off, or
the microcontroller may miss
counts. The red LED should blink
after each count.
Part B: 64 second timer
Turn slide switch S1 off and on
to reset the circuit, and wait for
the green LED to come on. Push
press switch S2 and hold it down
until the green LED turns off.
After a short pause, the red LED
will come on and stay on for
about 64 seconds.
-13-
We measure many things in
quarters. This picture shows
only a few of them. How many
more can you think of that uses
a system like this?

Turn off the slide switch (S1). Use the circuit from the preceding
project, but add parts to it so it matches the one shown here.
Set the lever on the adjustable resistor (RV) to the middle.
Turn on the slide switch (S1), and wait a moment for the green
LED (D2) to come on. Slowly press the press switch (S2) six
times, then press it again but hold it down until music starts. The
red & green LEDs blink in time as a song plays. You can adjust
the sound volume using the lever on the adjustable resistor. The
green LED will stay on when the song is finished.
The microcontroller can produce other tunes. Push the press
switch several times (not six times), and then hold it down until
an alarm plays. The green LED will come on when the alarm is
finished.
You can still use the circuit as a counter like in the preceding
project. To count, press switch S2 several times then wait 10
seconds (don’t hold S2 down). The LEDs will display the count
as before, without music.
Project A5 Adding Sound to the Counter
Project A6 Daylight Alarm Clock
Note: This circuit requires program Electronic Brain to be in microcontroller U21’s
memory. This is loaded into U21 at the Snap Circuits®factory and should still be there,
unless you already reprogrammed it. If it has been reprogrammed, you must use project
B1 to load program Electronic Brain back into U21 before building this circuit.
-14-
Use the preceding circuit, but replace the press switch (S2) with
the photoresistor (RP). Place the circuit in a dark room and turn on
the slide switch (S1). The green LED (D2) will come on, indicating
the circuit is working.
When a room light is turned on for more than 10 seconds, or
sunlight makes the room bright, an alarm will sound. The warning
will repeat approximately every minute until the slide switch is
turned off or the
room is made
dark again.
In darkness, the
photoresistor has high
resistance, like a switch
that is turned off. When
light shines on it, the
photoresistor has much
lower resistance, like a
switch that is turned on.

Use the circuit from project A5, but replace the press switch (S2)
with the 100Wresistor (R1). Place a business card or old
playing card under one end of the 100Wresistor, as shown.
Tie a fine black trigger thread on the card and the other end of
the thread to a fixed object in the room. Make sure the trigger
thread stretches across a walk path or in front of a door that will
catch the trigger thread when opened. Turn on the slide switch
(S1). The green LED will come on indicating the alarm is active.
When an intruder trips on the trigger thread, the red light will
come on for a few seconds and then the alarm will sound. The
warning will repeat every minute until the slide switch is turned
off or the card is placed back under the 100Wresistor. You can
adjust the sound volume using the lever on the adjustable
resistor (RV).
Note: After the circuit has been on for several minutes without
being triggered by an intruder, the green LED will turn off. Don’t
worry, your alarm circuit is still working. The software running
the microcontroller (U21) has a shutdown feature, which
preserves battery life when there isn’t much happening. The
microcontroller is sleeping, but it will wake up if an intruder
triggers the alarm. Turn off the slide switch (S1) to turn off the
circuit completely.
Note: This circuit requires program Electronic Brain to be in
microcontroller U21’s memory. This is loaded into U21 at the Snap
Circuits®factory and should still be there, unless you already
reprogrammed it. If it has been reprogrammed, you must use project
B1 to load program Electronic Brain back into U21 before building this
circuit.
Project A7 Intruder Alarm
Trigger Thread
-15-
The green LED uses about 20mA
of electricity when it is lit. This isn’t
much, but it will drain the batteries
after several days when it is left
on for 24 hours a day. Battery-
preserving shutdown modes are
an important feature of micro-
controllers.

Set the lever on the adjustable resistor (RV) to the middle.
Turn on the slide switch (S1), and wait a moment for the
green LED (D2) to come on. Push the press switch (S2)
and hold it down until music starts. The red & green LEDs
blink in time as a song plays. You can adjust the sound
volume using the lever on the adjustable resistor. The
green LED will stay on when the song is finished.
The microcontroller (U21) contains four songs that are
built into memory and cannot be erased. Each of these
can be programmed to play and flash lights. The
machines that play songs on command are called
“jukeboxes”. A jukebox is a partially automated music-
playing device, usually a coin-operated machine, that can
play specially selected songs from self-contained media.
You just made a simple jukebox!
Select a song to play when the green LED is on and not
flashing. S2 presses are cumulative, unless you turn the
slide switch on and off between songs.
1) Press and hold down S2 to play “Birthday Song”.
2) Press S2 once, then press it again and hold it down
for “Jingle Bells”.
3) Press S2 twice, then press it again and hold it down
for “Silent Night”.
4) Press S2 three times, then press it again and hold it
down for “Rudolph the Red Nose Reindeer”.
5) Press S2 four times, then press it again and hold it
down for all of the above songs in reverse order.
6) Press S2 five or more times, then press it again and
hold it down to play another familiar song.
Project A8 Jukebox
CAN YOU PLAY
THREE BLIND MICE?
-16-
Note: This circuit requires program Electronic Brain to be in microcontroller
U21’s memory. This is loaded into U21 at the Snap Circuits®factory and
should still be there, unless you already reprogrammed it. If it has been
reprogrammed, you must use project B1 to load program Electronic Brain
back into U21 before building this circuit.

Project A9 Counting To The Stars
Note: This circuit requires program Electronic
Brain to be in microcontroller U21’s memory.
This is loaded into U21 at the Snap Circuits®
factory and should still be there, unless you
already reprogrammed it. If it has been
reprogrammed, you must use project B1 to load
program Electronic Brain back into U21 before
building this circuit.
The circuit will count how many times you
press switch S2, play some music, and then
spin the fan for a duration based on how many
times you pressed the switch.
Part A. Turn on slide switch (S1) and wait a
moment for the green LED (D2) to come on.
Press switch S2 once; the red LED (D1)
flashes. Wait for the green LED (D2) to turn off
(about 10 seconds after you press S2). When
the green LED comes back on, press and hold
down S2 until music starts. The motor (M1) will
spin for 1/4 second and stop. The green LED
will come back on, indicating the time has been
reset.
Part B. Now press switch S2 three times, and
wait for the green LED to go off. The red LED
will flash three times, indicating the motor will
spin for 3/4 seconds. Press and hold down
switch S2 until the music starts. The motor
should spin for 3/4 seconds, and the fan may
rise into the air.
Part C. Now press switch S2 ten times, and
wait for the green LED to go off. The green
LED will flash twice and the red LED will flash
twice. Each green flash equals 1 second and
each red flash equals 1/4 second, so the motor
should spin for 2 and 1/2 seconds. Press and
hold down switch S2 until the music starts. The
motor should spin for 2 and 1/2 seconds, and
the fan will rise into the air.
Part D. For each time you push the switch, the
motor will spin for 1/4 second. Press switch S2
up to fifty times, and wait for the green LED to
go off. The green & red LEDs will flash based
on the motor spin time you entered; each green
flash equals 1 second and each red flash
equals 1/4 second. Press and hold down switch
S2 until the music starts. The motor should spin
for the duration you entered; if the time is long
enough then the fan will rise into the air.
-17-
!
WARNING: Moving parts.
Do not touch the fan or
motor during operation. Do
not lean over the motor.
This complex circuit is
pictured on the box cover, use
that as a guide to help build it.
The program in the
microcontroller IC (U21)
controls power to the motor
(M1), flashes the LEDs (D1 &
D2), and sends music to the
speaker (SP).
The microcontroller is like an
electronic brain running the
circuit.
+

Project A10 Angles and Distance
Use the same circuit as project A9, but place a
book or other object under the base to create a
launch angle as shown. Place a piece of paper or
short box on the floor approximately three feet in
front of the snap circuit base. This paper/box is
the target area landing zone.
Turn on slide switch (S1) and wait a moment for
the green LED (D2) to come on. Push the press
switch (S2) as many times as desired, then press
it again and hold it down. When an alarm starts,
release S2. When the alarm stops, the motor (M1)
should spin for a while, and then the fan should
launch toward the target. Repeat, pressing S2
more or less times. The more times you press S2,
the higher/farther the fan should fly. See who can
land the fan on the paper/box with the fewest
launches.
BOOK CIRCUIT TARGET
!
WARNING: Moving parts.
Do not touch the fan or
motor during operation. Do
not lean over the motor.
Note: This circuit requires program Electronic Brain to
be in microcontroller U21’s memory. This is loaded into
U21 at the Snap Circuits®factory and should still be
there, unless you already reprogrammed it. If it has been
reprogrammed, you must use project B1 to load program
Electronic Brain back into U21 before building this circuit.
-18-
+

Project A11
Build the circuit, leaving
one end of the black
jumper wire unconnected.
Turn on the switch (S1).
One LED (D1 or D2) will
be on, the other off.
Alternately touch the
loose end of the black
jumper wire to the snaps
marked “A” and “B” in the
drawing. When you do,
both LEDs change
between on and off. One
LED “flips” on and the
other “flops” off.
Flip-Flop
Project A12
Build the circuit, turn on the slide switch (S1), and push the press
switch (S2). The red LED (D1) will be on for a little while. Push
the press switch again to turn the LED back on. Move the lever
on the adjustable resistor (RV) to adjust how long the LED stays
on for.
Adjustable Light Timer
-19-
This circuit is known as a “flip-flop” due to the way
it operates. Variations of this circuit form one of
the basic building blocks for computers. This
circuit can be thought of as a memory because it
only changes states when you tell it to, it
“remembers” what you told it to do, even though
you removed the loose wire. By combining
several of these circuits, you can remember a
letter or number. A typical computer has
thousands of flip-flops, in miniaturized form.