SNAP CIRCUITS
INSTRUCTIONS
READ EVERYTHING CAREFULLY
& you will learn more
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Make sure ALL parts are in place before beginning
Follow the Projects in order. Upon finishing, feel free to experiment
The BLACK numbers show which pieces to put down 1st, 2nd, or 3rd
Before turning the switch, check all drawings match EXACTLY, including +
and – symbols! Check all connections are securely snapped.
Check for SHORT CIRCUITS and remove any dangers!
DISCUSSION YOUR OBSERVATIONS, WRITE THEM DOWN, and HAVE FUN!
#1
SERIES CIRCUIT with LIGHT
OBJECTIVE: To show how a switch turns an electrical
circuit “ON” and “OFF”.
Build the circuit at left by placing all the parts with a black “1” on
the base first. Then, place down all the parts with a “2” next to
them. Screw the bulb into the lamp socket (L1).
When you close the slide switch (S1), the current from the battery
flows through the lamp and through the switch and then back into
the battery. This is an example of a closed circuit – electricity can
flow because the circuit is connected. When you turn the switch to
the “OFF” position, this opens the circuit and electricity stops
flowing.
#2
SERIES CIRCUIT with FAN
OBJECTIVE: To show how electricity can be used to run a
Direct Current (DC) motor.
Build the circuit at left by placing all the parts with a black “1” on
the base first. Then, place down all the parts with a “2” next to
them. When you close the slide switch (S1), the current from the
battery flows through the motor (M1) and through the switch and
then back into the battery. Place the fan blade on the motor shaft.
WARNING: When you turn on the switch, there will be moving parts. Keep
your head and face away from the fan blade AT ALL TIMES.
When you are ready, put the switch in the “ON” position to close
the circuit. The motor with rotate, turning the fan blade. We are
changing electrical energy from the battery into mechanical energy
in the motor turning the fan blades. DC Motors are used to power
cordless drills, electric toothbrushes, model trains and planes, and
much more! Electric motors are much easier to control than gas
motors (combustion engines) in cars.
#3
SERIES CIRCUIT with FAN
OBJECTIVE: To make a circuit that launches the fan blade
into the air to simulate a flying saucer or frisbee.
Rebuild the circuit from Project #2, but reverse the polarity
(direction) of the motor – pay careful attention to the + sign. When
you close the slide switch (S1), the motor will begin to turn and
increase in speed. When the motor is spinning as fast as it can, turn
the switch off. The fan blade should rise and float into the air. Be
careful not to put your face over the fan blade or it will hit you!
The air is being blown down by the blades as a result of the motor
turning. When the switch is turned off, the fan unlocks from the
motor and flies into the air. If the speed of the rotation is too slow,
the fan will remain on the motor because it does not have enough
power to lift off.
If the fan doesn’t fly off, try turning the switch on and off several
times when it is at full speed.
#4
SERIES CIRCUIT with LIGHT AND FAN
OBJECTIVE: To show how voltage affects speed of a DC
motor and can decrease lift of the fan.
Change the circuit in project #3 by adding the lamp (L1) in series (in
a row) with the motor as shown in the diagram on the left.
When you place the lamp in series with an electronic device, it will
draw less current because the lamp takes some of the electricity (it
creates resistance). The lamp reduced the amount of current
through the motor, and that reduces the top speed of the motor.
Close the switch (S1) and wait until the fan reaches the maximum
speed. Open the switch (turn it off) and see if the fan launches and
how high it reaches. In many cases, it may not launch at all.
#5
SERIES CIRCUIT with LIGHT AND FAN (Same Parts, Different Arrangement)
OBJECTIVE: To show how a lamp can indicate when a
motor is running.
Rearrange the circuit from Project #4 to follow the diagram on the
left. When you close the switch (S1), the fan will spin and the lamp
(L1) will turn on. The fan will take a while to build up speed because
a significant amount of the electrical current is going into the lamp
instead of the fan. Does the light get brighter if you remove the fan
blade from the motor? Why or why not?
If you read this, raise your hand and call over a teacher to let them
know you’ve been reading the directions. Good work!! Keep it up!
#6
PARALELL CIRCUIT with LIGHT AND FAN
OBJECTIVE: To show how an indicator light can be
connected without affecting the electrical current to the
motor (without decreasing the speed of the motor).
Change the Project #5 setup to look like the drawing on the left. Be
sure to place the pieces with a black 1 next to them first, and then
all the pieces with a black 2 second.
When you close the switch (S1), the fan and the lamp should both
turn on (the fan might spin very slowly or not at all if the batteries
are weak). In this PARALLEL circuit, the lamp does not take any of
the current that goes to the motor. Remove the fan and notice how
the lamp does not change in brightness as the motor spins a little
faster. Both the motor and light have their own paths to the battery.
#7
PARALELL CIRCUIT – 2-Speed Fan and Light
OBJECTIVE: To show a parallel circuit with variable
(changing) fan speed.
Build the circuit at left. When you close the slide switch (S1),
current flows from the batteries, through the switch and into the
motor and fan. The current then flows into the light, UNLESS the
press switch (S2) is pressed down. When the S2 switch is ON, the
current travels through the switch instead of the lamp.
When the current travels through the light, the fan spins slowly.
When the press switch (S2) is ON, the light receives no current
and the fan speeds up.
#8
PARALELL CIRCUIT – Musical Doorbell
OBJECTIVE: To show how a full circuit can be used as a
musical doorbell.
Build the circuit show at left. When you close the slide switch (S1),
the music circuit (U1) may start playing a song and then stop. Each
time you press the switch button (S2), the song will play again.
Musical circuit boards like the one inside of U1 are used in many
toys that play music and make noises. Many songs are able to be
stored on circuits smaller than the tip of a pencil.
#9
PARALELL CIRCUIT – Sound Activated Whistle Chip
OBJECTIVE: To show how sound can be turned ON and
OFF in an electronic device (circuit).
Build the circuit show at left, starting with the parts with a black 1
first. Connect the speaker last using the jumper wires as shown.
When you close the slide switch (S1), the music may play for a bit
and then stop. Once the music stops, clap your hands close to the
whistle chip (WC) or tap on the base with your finger. The music
should play for a bit again and then stop.
#10
PARALELL CIRCUIT – Police Light Siren
OBJECTIVE: To build a police siren activated by light.
Build the circuit show at left. Cover the photoresistor (RP) and
turn the slide switch (S1) ON. A police siren with music is heard for
a while and then stops. You can start and stop the siren by
covering or uncovering the photoresistor.
#11
PARALELL CIRCUIT – Space Wars
OBJECTIVE: To use the space wars circuit to make
sounds.
Build the circuit show at left. Close the circuit by fipping the slide
switch (S1), or pressing the press switch (S2). Do both several
times in combination. You will hear an exciting range of sounds, as
if the space war is happening!
The space wars circuit can play a variety of sounds stored inside .
#11.5 Space Wars Light Resistor
OBJECTIVE: To use the space wars circuit to make sounds with a light switch.
Use the circuit you created in Project #11, but replace the slide switch (S1) with the photoresistor (RP).
The circuit immediately makes noise. Try turning it off!
If you experiment, you can see the only way to turn it off is to cover the photoresistor (or turn off the
lights in the room). Since light is used to turn on the circuit, you might call it a “light switch”.
The photoresister contains material that changes its properties when exposed to light. As it gathers
more light, the material becomes better at carrying electrical current. For example, street lights use this
technology to know when it is dark out and when the light should be turned on and off.
Good Work!
Hopefully you read all the instructions 
Answer the following questions, then feel free to explore and try to create different circuits.
• What is the difference between a series and parallel circuit?
• If you add a light to a circuit, what will that do to the other parts
connected to the circuit?
• How does a lightbulb act as a switch in a circuit?