Here are some simple instructions for making a crystal radio. These particular instructions are derived from the second radio my daughter and I recently built, but they can be modified in any number of ways to make a variety of crystal radio designs.

There is a parts list and a tools list at the bottom of this page.

These instructions do not go into the how and why a crystal radio works.

• Find or make a base for your radio. It must be big enough to fit the coil, wiring, and components. The base we used measures roughly 11X10X1″.

• Find something for a cylinder around which you will wrap the magnet wire, making a coil for the radio. The first radio I made used an empty conditioner bottle; this radio is made with a Metamucil container. You can use a rigid cardboard tube, a non-rigid tube that you make rigid by applying glue or some kind of lacquer, a length of PVC or other plastic piping, or something similar. I’ve read that many people use something that is between 1 1/2″ to 2 1/2″ in diameter. The tube should probably be between about 6″ to 12″. The container we used is about 7 1/2″ long.

• Wrap the tube with magnet wire. We used 22 AWG, but I’ve read of people using a variety of gauges. Remember, the lower the number, the thicker the wire. The higher the number, the thinner the wire. Any kind of insulated wire can work, but I think magnet wire is the best and easiest to work with. Magnet wire has a thin enamel coating that insulates the copper wire underneath, like plastic sheathing does on the wire in any electrical cord you plug into a wall. It’s important to have insulated wire for the coil so that the current has to follow all of the turns in the coil, thereby creating a magnetic field (quick note: I am a complete novice when it comes to radio and electronics…to get a better understanding of how and why a crystal radio works, I encourage you to do some research online…there are lots of resources that explain the science behind this project!).

• Make small holes in the cylinder, through which you can run the magnet wire. This will help keep the wrapped wire securely in place.

• Affix the wire-wrapped cylinder to the radio base. We used hot-glue; it can be stapled, screwed, clamped, etc.

• One end of the wire used for the coil will connect to the right side of the wiring on the base, and the other side will connect to wiring on the left side of the base. We set ours up as the blueprint below indicates: the magnet wire on the left of the coil connects to our antenna wire; the magnet wire on the right connects to the resistor, earpiece, diode, tuning wiper, and ultimately the ground wire.

• Remember that the magnet wire is insulated…that means that wherever you are tying into something else (like the antenna or resistor or ground wire), you must remove that insulation, so the radio current can transfer. We simply sanded the surface of a couple of inches of the ends of the magnet wire, exposing the bare copper underneath.

• Likewise, you must remove the enamel along the strip of the coil that the wiper tuner comes into contact with when you move it left or right. This way, the tuning wiper (the brass rod on this radio) comes into contact with the wire of the coil and the radio current passes from the coil to the wiper and into your earpiece. When you connect the wiper to the radio base (and to the wiring from the earpiece and the ground), you want to make sure all the connections are snug, while also making sure the wiper can still move. This way, it will be in contact with the coil and you can tune the radio, hopefully finding a station or two, by simply moving the tuning wiper left or right along the coil.

• All the little ‘x’ marks on the diagram below indicate where we used screws and washers. We wrapped wire around the screws, sandwiched between two washers on each screw, and tightened with a screwdriver. This pinches the wires together, helping to ensure good contact. Some people solder these connections and/or use Fahenstock clips.

• Once you have everything set up on the radio base, you are ready to tie into the antenna and ground wires. The antenna can be pretty much any wire. It can be left-over magnet wire, old cords, pretty much whatever. The higher you can get the antenna, typically the better, athough I read a story about POWs tying a homemade radio into the barbwire surrounding the prison camp. This fencing resulted in a huge antenna that captured radio-waves well. It’s best to have any part of the antenna that rests on or touches something be insulated. DO NOT put your antenna in contact with or close to power lines.

• The ground can be any metal that is driven into the earth. The first radio I made was in a basement and I ran the ground wire to an exposed piece of metal plumbing. This acted as a decent ground. You can drive a copper pipe into your yard and connect to that, or try something similar. DO NOT connect your ground wire to a natural gas pipe.

• Both the antenna and ground are temporary connections. DO NOT leave your radio connected to the antenna and ground when not in use. This is dangerous during electrical storms, as lightning can strike and follow the wiring to your radio. Don’t leave them connected and DO NOT operate your radio during lightning storms. Our most recent radio works pretty well without even connecting to the antenna or ground, although it has better reception and volume when it is connected to both.

Parts list:

• base (we used a section of a 1X12″ pine board)
• cylinder (1 1/2″ to 3″ diameter; 6″ to 12″ length)
• magnet wire (we used 22 AWG)
• tuning wiper (we used a brass rod (12″ length and 1/16″ diameter); can be any conductive metal)
• high-impedance earphone (sometimes called a piezoelectric earphone)
• wire (for connecting components on the base and for the antenna and ground wire)
• diode (we used a 1N34A germanium diode)
• resistor (optional; we used a 47K ohm resistor)
• screws
• washers
• alligator clips (optional)

Tools list:

• saw
• pin vise or drill
• screwdriver
• wire cutter/stripper
• electrical tape
• hot glue gun (optional; cylinder can be attached in a number of ways to the base)
• needle-nose pliers
• hobby knife
• sandpaper