Remote Control Car
Introduction
This remote control car project serves as a good introduction to some basic
principles of electric circuitry. We will learn how to build a remote control
system from scratch by connecting the motor and electrical wiring to the
switchboard. The project will also teach us the differences between parallel
and series circuits and finally show us how to draw a proper circuit diagram
using the electrical symbols for motors, batteries and switches.
Time: 3 hours
Engineering and Scientific Background
Electricity is the flowing movement of electrons through a conductive
substance (like water or metals). An insulating substance is one where no
electrons can move or they move with great difficulty (like wood and plastic).
The electrons move by jumping from one atom to another (see complete
definition of electricity in the Toilet Paper dispenser write-up). The
batteries are what give the electrons a push to start their movement. We
call the continuous circle where the electrons pass (from the battery to the
components and then back to the battery) a circuit. A circuit needs a
minimum of wires and the battery. Here are some examples:
Now, if we wanted to turn on a light or a motor, we would have to put it
inside the circuit. The electrons must be able to pass through the wires,
then through the component (light or motor) and go all the way around, to
finish off where they started. When the electrons do this continuous
circular motion, the circuit is said to be closed.
Materials
- 4 long pieces of electrical wiring (about 100cm each)
- 11 short pieces of electrical wiring (about 15cm each
-
2 3V motors
1 9V battery
1 bamboo BBQ skewer
4 film canister lids
1 elastic band
Chicken wire or paperclips
1 straw
-
Scrap pieces of cardboard
2 paper clips
1 nail
Glue gun
Scissors, x-acto knife
Tape
Decorating supplies
Cautions and Warning
- Ask a grown up to help you when using the glue gun and x-acto knife.
- Do not touch both poles of the battery at the same time with any part of
the body as this may cause a severe electric shock.
- Nails and bamboo skewer have one very sharp end. Use caution when
manipulating these objects. To avoid injury, tape these ends when not in
use.
Procedures
NOTE: Refer to the drawings at the end for more precise instructions on
how to build your car.
1- Cut out a 30cm x 20cm piece of cardboard. This will be the base of
your car.
2- Poke holes in the centre of all 4 film canister lids with the nail or
BBQ skewer.
3- Pass the prong of each motor through the hole in the centre of a lid
(2 lids with a motor in each). Glue the lids to the prongs. These will
become your two back wheels!
4- Cut your straw about the same length as the width of your car.
5- Put the skewer through the straw and then put the remaining two
film canister lids on each side of the skewer. Glue them to the
skewer. These are your front wheels. Cut off the extra skewer that
is sticking out of the sides.
6- Follow the drawing and glue your front and back wheels to the
cardboard.
FOR THE NEXT STEPS, make sure each end of each wire is well sanded
to take off all the enamel coating.
7- As shown on the drawing, connect one short piece of wire to each of
the four terminals of the 2 motors and tape them in place.
The car is now physically ready and all we need is to do is build our
circuits.
CIRCUITRY
Start planning your circuits by building the control pad.
drawing closely.
Follow the
1. Cut out a 20cm x 20cm piece of cardboard. This will be the control
pad.
2. Make a battery container in the centre of your pad, by gluing two
small scrap pieces of cardboard or Popsicle stick on either side (like a
small box with only three sides). The distance between the two pieces
you glue should be about 1 ½ times the width of the battery. Use the
elastic band or masking tape to hold the battery in place.
3. As shown on the diagram, tape three short pieces of chicken wire to
the cardboard in front of the battery. The ends of the wires nearest
to the battery should be lifted off the cardboard and twirled so they
can touch the clips of the battery. The wires and battery slot should
be spaced in a way that when the battery is shifted to the side, the
wires touching the terminals alternate (only 2 wires should touch the
battery at all times to avoid short circuits).
4. Take the two outside chicken wires, lift the ends furthest from the
battery and twist them together. Make sure they are a bit elevated
so they do not touch the wire in the middle.
5. Tape two short pieces of wire on the cardboard on each side of the
battery slot. Bend into L shapes (see figure).
6. Bend both paper clips into V shapes. Twist a short wire around the
smaller end of each paper clip. Glue them to the cardboard so that
the lifted ends are above the pieces of wire. These are our switches.
7. Now, we need to connect our pad and car with the long pieces of wire.
Follow the patterns shown on the diagram. It helps to work on one
motor at a time. When all the wires are connected to it, verify that it
works by pressing the paper clip down. Note which way the wheels are
turning.
8. When the first motor is done, connect the second. Once again verify
that it works. Make sure both wheels are turning in the same
direction. If they aren’t, simply switch the wires on the clips of the
motors’ terminals.
Conclusion
Everything should now be working. Pressing both paper clips down at the
same time will make the car go straight. Pressing only one at a time will
make it turn. Sliding the battery to the opposite side in its slot will make
the car go in reverse.
Questions:
1- How does the car turn if the front wheels don’t move?
2- Can you name a vehicle that uses this technology to turn?
Answers
1-
2-
Well it’s very simple. When we hold down only one of the paper clips, only one of the wheels work. Because
only one side of the car is being pushed forward, the entire vehicle turns on itself. Both wheels need to turn
together for the car to advance.
The tank works on the same principles. In the case of a tank, when it is making a turn, only one of its tracks is
moving.