Introduction: Simple Paper Circuit LED Flashlight
This is a great introduction to DIY electronics for kids. It uses a standard sized business card as the template and basic components to make a solder-less circuit. Ideal for children aged four to ten. Adult assistance is recommended especially for the younger ones. The Kauai Makerspace (www.kauaimakers.org) presented this project at the Honolulu Mini Maker Faire and it was a huge success. The PDF template we used has been included in this instructable. Feel free to use it or come up with your own schematic.
Step 1: Tools and Materials
You will need the following items for this project:
- Business card with schematic
- 1/8" Copper Foil
- CR2032 Battery
- Safety Scissors
- 5mm LED
- 200 Ohm Resistor
Step 2: Lay the Copper Foil
Note: Keep the spool in the plastic bag. Cut a slit in the plastic bag to pull out just enough copper foil as needed. The copper foil will completely unravel if it is removed from the bag.
Cut a 6-inch section of copper foil from the spool using scissors.
The copper foil will coil up and become useless if you pull the paper backing completely off.
To prevent this from happening, begin by peeling the paper backing away from copper foil just a little bit, maybe a half inch at the most. Use this piece to start affixing the copper tape to the card where the dashed lines are. Peel the paper backing off as needed while you lay the copper tape to the card. You will need to place a total of three segments of copper tape on to the card. After completing the first segment, the easiest way to end it is by ripping the copper foil. Repeat this process for the other two segments.
The best way to handle the 90-degree bends is by folding the foil tape to maintain one continuous segment. If the foil breaks, just overlap the two segments.
Make sure the copper foil tape is one continuous segment from the battery to the other side of the card to the LED.
Make sure the copper foil tape is not crossing over from one side of the card to the other on the edge where the LED is supposed to go.
Step 3: Resistor
Once the three copper foil tape segments are laid out, you are ready for the resistor. Take one resistor and put a 90-degree bend in one of the leads to make an 'L' shape. Place the resistor over the resistor icon. Make sure it lines up over top of the copper foil tape. Use invisible tape to secure it on top of the foil tape.
Note: The direction of the resistor does not matter.
Step 4: LED
You are ready for the LED after you've secured the resistor. The LED is directional meaning that current can only flow through it in one direction. To make sure you correctly place the LED on to the card the right direction, take a look at the LED. You will notice one of the leads is shorter than the other. The shorter lead is the negative lead and the longer lead is the positive lead. Place the card in between the two leads with the shorter lead is on the same side as the battery. Tape the LED in place over the copper foil on both sides of the card.
Step 5: Battery
Place the battery on the card with the '+' side facing up. You need to tape the battery in a special way to keep the center of it exposed. The best way is to put two pieces of tape on either side of the battery, leaving a vertical line in the middle of the battery exposed. This line of exposed area should match up with the copper tape above it.
Step 6: Fold
Fold the card in half lengthwise. This should close the circuit and cause the LED to temporarily light up.
If it lights up, fold the card again so the logo is facing outward. You have now completed making a paper LED flashlight. The LED should light up when you squeeze the paper flashlight.
If the LED does not light up, go to the next step to begin troubleshooting.
Step 7: Troubleshoot
Most often, the copper foil tape is not laid down well. It could have a poor connection if there are multiple breaks or overlaps in each segment.
Another common issue is a bad connection between the components (LED, Battery, or Resistor) and the copper foil. Make sure the invisible tape securely holds the components directly over the copper foil.
Double check to make sure the battery is '+' side up and the LED is oriented the correct way with the negative lead on the same side of the card as the battery.
Make sure the battery and LED are working. You can test both at the same time by putting the battery between the two leads of the LED - Short lead on the negative side of the battery. They both work if the LED lights up. Change out the LED or battery and repeat this test if the LED doesn't light up.
One sneaky problem is when the copper foil is one continuous piece from the resistor past the LED and on to the back side of the card. There must be a break in the foil at the edge where the LED is located.
If none of this helps, it is best to start over from scratch using a new card. You should still be able to use the same components.
Step 8: Done!
Congratulations! You have now successfully created your very own LED paper flashlight. We hope this inspires you to make other electronic circuits.