1. LED Flashlight

2. How does it work?
When electricity flows through an LED (light-emitting diode), the LED lights up
We need a battery, two LEDs, some wire, a switch and some know-how!

3. Need to learn some things
How to read an electrical schematic
What parts we’re using
How to build the flashlight

4. Reading Schematics:
What’s this?
Battery

5. How about this?
Resistor

6. What’s this? Diode Lets current flow one direction but not the other
YES X NO

7. Electrical circuit
Must have a closed path all the way from one terminal of the battery to the other

8. Will current flow?

9. How about here?

10. And here?

11. Will current flow?

12. How about now?

13. Schematic versus real life
long lead is anode
anode
cathode

14. Here’s our battery Called a coin or button battery
This one is only 3 V
Hey, we don’t need a resistor then!
Notice the top is positive- that should connect to the anode (long lead)

15. Are you ready to build? Cereal box Paper template Coin battery 2 LEDs
scissors, paste, wire, tape, paper clip, aluminum foil, sandpaper
pen or pencil

16. Cut the cereal box open

17. Then cut it into 2 halves

18. Look at template
FRONT
BACK

19. Cover all black lines with paste

20. Turn it over and paste template to cardboard

21. OK, cut it out- solid lines only!

22. Punch out the two holes

23. Fold box on dotted lines

24. LEDs: one lead is shorter!
If you forget which is shorter, look for the flat

25. Color the top of the short lead

26. Bend legs at the knees
Short!
Short!
Short!
Short!

27. Twist together the two short leads
Here’s a handy twisty tool
Dowel with two 1/16” holes
Put both SHORT leads in holes
Twist
Repeat with other legs

28. End result
Which are the short leads?

29. Bend LEDs toward each other
Don’t let short leads touch the long leads!

30. Got three pieces of magnet wire?

31. Burn insulation off the ends
Then sand off the black stuff

32. Twist one around the SHORT leads

33. Use a pen or pencil to make a small loop in the other end

34. Tape loop to bottom (-) side of battery

35. Make a loop in another wire and tape it to the top (+) side of battery

36. Here’s a chance to test it!
Touch, don’t twist!
Touch the other end of the second wire to the other LED leads.
It should light up.

37. Bend the paper clip a little
Twist the end of the second wire to the paper clip

38. Tape the big loop of the paper clip to the outside of the box
Cover the big loop with tape

39. Get the last piece of wire
Slide one sanded end under the top part of the clip
This is going to be your switch!
Must be sanded part!!!

40. Tape it down ONY THE END

41. Twist the other end of the last piece of wire to the long leads of the LED
Test it! Close the switch! Does it light up?

42. Poke the LEDS through the holes
Tape down wires from the switch
Tape the battery to the inside of the box somewhere

43. Fold up the box and tape it

44. You are all done

45. How does it work?
What is this?
What is this?
What is this?