Layout and construction tips:
The layout shown above is approximately to scale, and should work satisfactorily for placement of soldering strips (numbered 1 - 5) and major components.
The 100 k resistor and the two fixed capacitors should be soldered at the ends of the strips. Other components will be located elsewhere on the strips. The position of the IC is shown.
When soldering, heat the strip, then melt a little solder in onto the strip and press the component lead in position. Ensure solder flows onto the lead and do not let the connection be disturbed for a few seconds after the soldering iron has been removed. Try not to let the soldering iron remain on the connection any longer than needed after the part has melted solder on the lead, particularly when soldering the leads to the IC, since it is somewhat heat sensitive. Ensure the soldering iron is hot before you attempt to use it.
Check to make sure the parts leads will fit properly before soldering. It may be necessary to bend the leads slightly and even hold the lead onto the strip when soldering - a partner may provide a third hand if this is a problem for you.
The glue holding the strips onto the board may melt and allow the strip to slide on the board when soldering it. This is not a problem as long as the strip is put back into place. When the glue cools, it will form a better bond with the board.
The black battery lead may be left under the 1 k resistor, as may be the red connection.
The battery holder should be secured well with hot glue on both long sides. Since there is no power switch, the battery is removed when the radio is not in use.
You will find that the radio is somewhat directional, and that stations can be brought in better often by turning the radio.
Follow the procedure in the order listed for best results. Refer to the drawing and the model as needed to keep from having to start over.
1. Starting 1 inch from the left edge of the board, cut and place
on the board the sticky copper strips as indicated:
#1 1 1/8 inch
#2 1 inch
#3 5/8 inch
#4 1 3/4 inch
#5 1/2 inch
2. Cut one lead of the coil to 1 inch in length and the other to 1 1/2 inches. Clean the enamel off about 1/4 inch of the end of each lead (should be a shiny copper appearance)
3. Cut each lead of the 100 kohm resistor to 1/2 inch in length (brown-black-yellow) and solder to strips 2 and 4
4. Solder the 10 nF capacitor (0.01 uF) between strips 1 and 2
5. Solder the 100 nF capacitor (0.1 uF) between strips 1 and 4
6. Cut the black battery lead to 3 inches long and strip off 1/4 inch of insulation. Solder it to strip 1.
7. Solder the red battery lead to strip 5. (note: if the length of this lead is too long, you can cut it to fit as you did with the black lead)
8. Test the earphone by putting it in your ear and touching the two leads together. If you hear a sharp click, the earphone is satisfactory.
9. Wrap a lead of the earphone to each lead of the 1 kohm resistor (brown-black-red), close to the resistor, and solder the earphone leads to the resistor leads.
10. Cut each of the 1 kohm resistor leads to 1/2 inch, and solder the resistor between strips 4 and 5.
11. Solder the center lead of the variable capacitor to strip 2, and the outside lead to strip 3
12. Solder the 1 inch coil lead to strip 2 and the 1 1/2 inch lead to strip 3
13. Solder the IC (integrated chip) to strips 1, 3 , and 4 as indicated; the flat side of the IC should be face down. You may spread the leads apart gently to reach.
14. Use hot glue to secure the variable capacitor to the board
15. Use hot glue to secure the coil to the board.
16. Run the earphone under the battery holder and to the right of the board. Use hot glue to secure the battery holder to the board. This keeps the fragile leads of the earphone from coming loose.
17. Use the small screw and the washer to secure the knob to the variable capacitor.
18. Install a battery into the holder - negative end to the spring,
and test the radio.