1. LIGHTHOUSE
Electronic circuit production

2. The components

3. The battery clip holds the 9volt battery which
powers the circuit. The red wire is
positive and the black is negative.
Current flows through the wire much
as the flow of a river, the current
flows in one direction from the battery from
positive to negative.
The battery clip

4. The resistor limits the amount of current
which flows to the L.E.D. it “resists” the
Current flow slowing it down.
It can protect delicate components in a
circuit from receiving too much voltage
and slows the current flow through the
circuit. Resistors are too small to have
Numbers printed on them so they have
a colour code printed in bands.
Your resistor is a 100K
The resistor

5. The L.E.D gives off visible light and is a common
component in lots of electrical equipment such as power
indicators on televisions.
It is known as an output component.
It has a positive leg (long) called the anode
and a negative leg (short) called the cathode
and it is important to remember this when
you solder this in your circuit.
The wrong way round and it won’t work
The Light Emitting Diode

6. The transistor can be used as an amplifier
or a switch to control the flow of current
around the circuit. It has three legs, the middle leg is the
base which activates the transistor, the positive or collector
and the negative or emitter. These need to
be soldered to the other components
correctly. It is semi circular in shape so
that you can tell which way round it goes.
- +
The transistor

7. The L.D.R is the most important component
in this circuit. It works like a resistor by limiting current.
Unlike a resistor which has a set value, resistance changes
based on the amount of light falling on the
surface of the LDR. This allows more
voltage to the L.E.Ds which in turn allows the
lights to come on when it begins to get dark.
These components are known as sensors.
The Light Dependent
Resistor

8. The wire is the glue that holds the components
together in the circuit. There are two colours
that match the flow of current, positive (red) and
negative (black)
It is vitally important your wires are soldered in
properly in order for the circuit to work.
The plastic serves as a non conducting
layer to prevent short circuits.
It also helps identify positive and negative in
wiring circuits.
The wires

9. CREATING THE CIRCUIT

10. Take your two L.E.Ds and
twist the positive and negative
legs together so they are attached
as in the diagram
APPLY SOLDER
Step 1

11. Prepare one black length of wire and one
red length of wire by stripping the ends
and twisting the exposed wire
APPLY SOLDER
Step 2

12. Twist these wires onto the legs of the L.E.Ds
Remember the red wire goes on the long leg
and the black one on the short
APPLY SOLDER
Step 3

13. Attach the resistor to the red wire
on the L.E.Ds
APPLY SOLDER
Step 4

14. Prepare two wires in the same way
for the LDR but in this case the red and
black wire can be on either leg as there
is no positive or negative.
APPLY SOLDER
Step 5

15. Prepare a piece of red wire and attach
it the center leg of the transistor.
you may need to bend the legs out
slightly to do this.
APPLY SOLDER
Step 6

16. You are now ready to solder the
circuit together.
Take your time to look at the
diagrams and ensure
your components are soldered to
each other in the right order
Preparation complete

17. Attach the black wire from the
LDR to one leg of the transistor
as shown. Make sure the transistor
Is the right way round.
APPLY SOLDER
Step 7

18. Now join the black leg of the
L.E.D to the remaining
leg of the transistor
APPLY SOLDER
Step 8

19. Next join the two red wires together
and solder them to the remaining
leg of the resistor
APPLY SOLDER
Step 9

20. The final step is to solder the battery
clip in place.
Step 1.The black wire goes to the leg of the transistor
which is attached to the LDR
Step 2. The red wire attaches to the wire leading
from the L.E.Ds at a point before the resistor.
A FULL DIAGRAM IS ON THE NEXT SLIDE
The final step

21. L.D.R
BATTERY
CLIP
RESISTOR TRANSISTOR
L.E.Ds
Complete circuit

22. • If you have completed the steps correctly you
should have a functioning circuit.
• Now all that remains is to attach the battery
• If you put your hand over the LDR the L.E.Ds should light up
• If this doesn’t happen;
• Check your soldering
• Check the components are soldered together correctly
• Check the positive and negative legs are the right way round
Testing your circuit

23. Building the house

24. A development net is a flat
shape which when folded
and assembled will become
a 3D object
The development net

25. Apply details to the outside
of your house to make
it more creative.
Colour in the walls and roof
And add flowers or a design
Maybe your school logo
Designing your house

26. The thick black lines on the
net are cut lines, cut along
These lines neatly with the
scissors.
The dotted lines
on this net are
fold lines. Carefully fold
along each of these points
Cut and fold

27. The areas at the sides of the house
re glue tabs and you should apply
The double sided tape to this area
Do not stick it together until the
Circuit is installed
Glue tabs

28. • The LDR goes through the small hole in the roof of the
net and is attached with tape
• The battery will be stuck to the floor also using tape
Putting in the circuit

29. • Double sided sticky tape is used on the glue tabs to
assemble the house
• Try to be neat when folding and assembling
Assembly

30. You have now created your first sensor operated circuit.
There is a pack of components for you to take home or to
assemble in school with your teachers.
Pass on what you have learnt to your classmates and see if
you can create your own sensor based projects.
Task complete