Penny-Powered Flashlight

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30 Minutes


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Power a flashlight with pennies so you can signal Spider-Man when you’re in need! No store-bought batteries necessary. Build the flashlight with an LED and a few other household supplies, and make your own power source with coins and cardboard.
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Gather seven pennies that were made in 1983 or later. You can tell when a penny was made by looking at the date on the front of it. Pennies made in 1983 and later have zinc in them, which is what we need for this project.


Put on your safety glasses and sand one side of each penny until it has a silver-looking finish. That’s the zinc! It could take a while to sand away the copper (brown finish), but the zinc is under there.


Place a penny on a piece of cardboard and trace around it six different times. Pour vinegar into the cup. Cut out the six cardboard circles and put them into the cup of vinegar.

Once they are completely saturated with vinegar, take the cardboard circles out and use a paper towel to wipe off the excess vinegar.


Now let’s build the battery. Cut a piece of duct tape about 1/2″ wide and 5″ long. Lay it flat on a surface — sticky side up. Place 1 sanded penny — zinc (silvery) side up — in the middle of the tape.


Place a cardboard circle on top of the penny. Place another penny — zinc side up — on top of the cardboard circle. Continue to do this until you’ve placed all pennies and cardboard circles in one stack. A penny with the zinc side facing up should be at the top of the stack.


Bring one end of the duct tape up along the side of the stack, wrap it across the top, and then down along the other side to where it meets the other half. Wrap the second half of duct tape in the same way over the first, affixing it across the bottom of the stack and cutting off any excess tape. The other two sides of the stack should remain open so we can attach the LED.


Take the LED and bend the wires, or leads, so the positive (+) lead — the longer one — can touch the zinc of the penny on the top of the stack. Bend the negative (–) lead — the shorter one — so it can touch the bottom penny’s copper (brown) side. It should light up!


Tinker with light and shadow as you figure out how to construct an addition for your flashlight so you can see Spider-Man’s face in the beam of light! See our first prototype below. How might you add in fine structures to get the web-like features to show on Spider-Man’s face?

Can you make the flashlight image look more like Spidey’s face? Reference image here.

You can also increase the voltage by adding more pennies and cardboard circles to your stack. Use a multimeter to measure how much voltage your stack of pennies is creating and compare that to the label on the batteries in an inexpensive calculator. Run two wires from your penny-pack to the battery compartment of the calculator. Note where the positive and negative wires need to attach, and test how much voltage your penny battery puts out before trying to use it.



Project Author - Marc de Vinck

I’m currently working full time as the Dexter F. Baker Professor of Practice in Creativity in the Masters of Engineering in Technical Entrepreneurship Program at Lehigh University. I’m also an avid product designer, kit maker, author, father, tinkerer, and member of the MAKE Technical Advisory board.

Electricity for Young Makers: Fun and Easy Do-It-Yourself Projects

Learning to be a maker has never been more fun. Lavishly illustrated with cartoons and drawings, this book guides the reader through six hands-on projects using electricity. Discover the electrical potential lurking in a stack of pennies – enough to light up an LED or power a calculator! Launch a flying LED copter into the air. Make a speaker that plays music from an index card. Build working motors from a battery, a magnet, and some copper wire. Have fun while learning about and exploring the world of electricity. The projects in this book illuminate such concepts as electric circuits, electromagnetism, electroluminescence, the Lorentz force and more. You’ll be amazed by the results you get with a handful of simple materials.


Please Note

Your safety is your own responsibility, including proper use of equipment and safety gear, and determining whether you have adequate skill and experience. Power tools, electricity, and other resources used for these projects are dangerous, unless used properly and with adequate precautions, including safety gear and adult supervision. Some illustrative photos do not depict safety precautions or equipment, in order to show the project steps more clearly. Use of the instructions and suggestions found in Maker Camp is at your own risk. Make Community, LLC, disclaims all responsibility for any resulting damage, injury, or expense.

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