A WW II 'Foxhole Radio'

by Lance Borden, WB5REX

Components

  1. one cardboard toilet paper roll

  2. one razor blade ( blue is best but a rusty steel one is ok, blue ones are "PAL Super Single Edge" by American Safety Razor Co.)

  3. one wire coat hanger

  4. #22 AWG wire ( enough for 100 turns around the TP tube )

  5. one pair headphones ( high ohm set is best i.e., 4000 - 2000 ohms )

  6. one large safety pin and #2 pencil lead ( detector )

  7. assorted glues, lacquer etc., to finish and hold stuff to the base


Schematic

                     razorblade / pencil lead ( detector )
      
                                |       pin 
           ant.---O-----O-------| <------O------0  0---
                  |             |                      |     
                  <  >                                 |                            
                  <  >                                 |  hi ohm. headphones
                  <  >   tuner/slider                  |
           coil   <  > <-----------------O------0  0--- 
                  <  >                   | 
                  <  >                   |
                  <__>                 ground



     Schematic as it appeared in the original ascii text version of this page

Assembly

  1. wind the coil and spray or paint it with lacquer or something to set it firmly

  2. scrape the paint or varnish off the wire hanger and use it as the tuner/slider

  3. spread the safety pin apart and bend the head to 90 degrees to use it as a base to screw the pin to the base board, the pin then sticks up to its 2 turns then down to the point where the pencil lead is attached ( by wrapping it with #22 wire ) to become the detector which touches the razor blade

  4. use sandpaper to remove the varnish from the coil wire where it will be touched by the tuner/slider.


Source: "Electronics Handbook" Volume XVII, Page 47

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