Potato Powered Calculator
Materials:
Potato clock-- $19.95 (Discovery Channel Store, or wherever you can find one)
Pocket calculator-- $2.00 (dollar store)
Galvanized nails (2) -- $.5 (hardware store)
Foot and a half of insulated copper wire-- $3.00 (hardware store)
Two potatoes or other fruits—(varies, check your local produce store)
Wire cutters-- $5.00 (hardware store)
Soldering Iron-- $1.00 (dollar store)
Solder-- $1.00 (dollar store)
There are three major components of the two-potato calculator:
1. The plastic body
2. Calculator module with two wire probes soldered onto the back of the unit
3. Jumper wire with attached probes
Process:
Step 1: Create your own wire probes
1. Cut the copper wire into three 5-inch pieces.
2. Strip the ends of the wires, leaving about a half inch of copper exposed. For two of the wires, strip one inch of insulator from one end of each. Twist them tightly.
3. Wrap one of the twisted ends around the neck of one of the galvanized nails, just below the head. Wrap it over itself like a twist-tie so it will not come undone.
4. Repeat with the remaining twisted wire and nail.
Step 2: Hooking up the wires to the potatoes
1. Insert copper side of wire into a potato.
2. Insert nail side of other wire into a different potato.
3. Connect remaining piece of wire between the two potatoes. Make sure that the nail end leads into the potato that has the copper from the first wire, and the copper end leads into the potato that has the nail wire. Also make sure to place connections as close together as possible to ensure the power reaches the calculator.
Step 3: Test the circuit and solder the wires
1. Take the back cover off the calculator (you may need a screwdriver) and remove the battery.
2. Only two wire ends should be unused at this point. Touch one end to one side of the battery connections, and the other end to the other side.
3. Try turning the calculator on. If it doesn’t work, switch the wire ends.
4. When you’re sure that the wires are leading to the right connections, solder them on. Ask your teacher, parent or guardian for help.
Voila! Your potato calculator is complete.
Note that you can remove the wires from the potatoes easily. Try different fruits and vegetables to see if they work as well as potatoes.