In the first part of the twentieth century building crystal radios occupied young boys all over America. Time and tide turned those young boys into soldiers fighting the Nazis in World War II.Hungry for some sort of diversion, they remembered their boyhood hobby and built simple radios out of scrounged materials. Copper wire, razor blades and safety pins brought music and a little recreation to help lighten the darkness of life at war.
Make a hole in each end of the paper tube on top and bottom using a hole punch. The holes need to be lined up one above the other so that you can push the magnet wire through easily.
Pull some magnet wire off the spool and insert it through the holes on one side of the tube leaving six inches sticking out. Fasten the wire to the tube with tape at the point where it comes out of the tube.
Wrap the magnet wire around the tube 120 times to form a coil. Make sure the wire loops are beside each other and not on top of each other.
After the coil is wound, pull an additional 8 inches of wire off the spool and cut it free from the spool. Push the end of the wire through the holes in the end of the tube and leave the end sticking out.
Place the tube coil down on the board and fasten it in place with tape. The terminal wires leading out from the coil should be sticking out from the bottom.
Screw a wood screw into the board near each end of the coil and wrap the coil terminal wires around the screws. The screw on the left is where the antenna wire is attached and the other one is for the ground wire.
Drive a screw part way into the board one inch below the ground wire screw and wrap one of the earphone wires around it. Wrap one end of the one inch piece of copper wire around the screw above the earphone wire and wrap the other end around the ground wire screw attached to the right side of the coil.
Place the blued razor blade on the board about three inches from the coil. Attach it to the board with 2 wood screws but don’t tighten them all the way down yet.
The Detector and Earphone
Bend the head of the safety pin back at an angle of 90 degrees with pliers. Poke the point of the pin into the graphite of the unsharpened end of the pencil.
Screw the safety pin to the board with a wood screw but do not tighten the screw all the way down. The safety pin should be positioned on the board so that the pencil point is touching the razor blade.
Wrap the wire from the other side of the earphone around the screw holding the safety pin and tighten the screw all the way down with the screwdriver.
Wrap one end of the six inch copper wire around the left hand screw holding the razor blade and wrap the other end of the wire around the antenna wire screw that is connected to the left side of the coil. Tighten the screws holding the razor blade with the screwdriver.
Wrap the end of the long antenna wire around the screw attached to the left side of the coil and tighten it down with the screwdriver. Wrap the ground wire around the other screw and tighten the screw. The signal flowing through the antenna can be heard in the earphone as AM radio when the ground wire is attached to something metal such as a pipe or radiator.
Things You'll Need
- Toilet paper tube
- Blued razor blade
- Magnet wire
- 2 inch piece of 22 gauge copper wire
- 6 inch piece of 22 gauge copper wire
- 8 Wood screws, Phillips head
- Paper clips
- Piece of wood
- Coat hanger wire
- One inch piece of pencil, with sharpened point
- Phillips screwdriver
- Hole puncher
- Earphone with the ends of the wire stripped
- 10 feet of copper wire for an antenna
- 3 feet of copper wire for ground
You can use a rusty nail as part of the detector if you can’t find a blued razor blade. Try and see how many other things you can find to make your radio work.
Watch the weather when using your radio. The copper wire hanging out your window makes a good conductor for lightning.
- single edged razor blade image by jimcox40 from Fotolia.com