How to make a simple radio set

You will now see step-by-step procedure to build an inexpensive crystal radio set and soon you will be able to send your voice hundreds of miles away as once Marconi did

Instructions

Difficulty: Easy

Things You’ll Need:

• 0.0003 uF (microfarad) variable capacitor.
• 2 oz. of 30 s.w. gauge wire for inductor
• Germanium diode
• High impedence earphones (2,ooo-4,ooo ohms)
• 4 wander plugs and sockets
• Tuning knob with pointer
• Aerial wire (5o-Ioo ft.)
• I sq. ft. of hardboard or plywood
• super glue

1. A cabinet for your crystal set can easily be made from a square foot of either hardboard or three-ply wood. Cut the parts required -- that is, two sides, back, front, top and base-using the measurements shown in the figure. Then drill the five holes in their right positions.
2. Glue the sides together, and slip two or three strong elastic bands round this frame to hold it firmly in place. Glue the top in position and weight it down with something fairly heavy until the glue is dry.
3. Cut out a semi-circular piece of paper, about three and a half inches in diameter, and paste it on the top of your cabinet just above the centre hole. This is the tuning dial on which you will mark the positions of the stations you receive.
   You are now ready to make the crystal set itself.
4. MAKING AND FITTING THE INDUCTOR :
   a) All you need for the inductor is a core and some wire (see list of parts). The core must be fairly firm so that the wire can be wrapped tightly round it, and the cardboard centre of a toilet roll is ideal for this purpose. Trim it to the right length for the cabinet and cut a small notch at each end to allow your screwdriver to get inside when you fasten the inductor in position.
5. b) Make two small holes near one end of the core, and secure the end of the wire by passing it into one 1 hole and out of the other. Draw out enough wire to make a connection later.
6. c) Wind the wire neatly on to the core, taking about sixty turns and making sure they do not overlap. (By experimenting with the number of turns on the coil you may find you can vary the stations you receive.) Make two holes at the other end of the core, and secure the wire by threading it through them as before. Wrap a layer of transparent tape round the wire coil to hold it in position.
   Now fasten your inductor in the cabinet with two small screws as shown in the diagram.
7. FITTING THE CAPACITOR
   Pass the spindle of the variable capacitor through its hole in the top of the cabinet and bolt it from the outside. Fit the tuning knob on top of the spindle
8. FITTING FOUR SOCKETS
   Pass each socket through the hole provided for it, and bolt firmly from inside.
9. SOLDERING THE CONNECTIONS
   Join up the various connections, soldering each joint as shown in the diagram. You can now screw the base on to the cabinet.Solder plugs on to earphones.
10. Insert aerial, earth and earphone plugs in their sockets, and adjust the tuning knob until a signal is heard. Mark the positions of the stations on your paper dial.
    Good luck and good listening!

Tips & Warnings

• The aerial should consist of between fifty and 100 feet of wire. It should be led outside if possible, though good results can sometimes be obtained by placing it round a picture rail. Take care to insulate it from all metal objects. And remember, the longer the aerial, the better the reception.
• A good earth is the water system of a house, because the pipes run underground. But an earth can be made by sinking a metal rod -- copper is best -- in a mixture of coke and soot that has been packed into a hole in the ground.