Shown here is a very basic crystal set mounted in a tobacco can, as shown in the January 1933 issue of Television News.
The design for this well-constructed little set apparently originated in a Danish magazine, and was adapted by one Clifford E. Denton, who put it together in a couple of hours one evening. The variable capacitor, shown as C1 in the close-up picture here, was a compression type. The plates did not rotate. Instead, the screw was turned to compress the capacitor, with an insulating material to keep the plates from shorting out. This component was known as a “variodensor.” The coil could be purchased, or made at home on a wooden form.
The most notable feature of this set was the fixed detector, bearing a brand name that apparently never quite made it in the world of radio. The detector was a “Piggly Wiggly crystal detector.” The magazine described the Piggly Wiggly as “much better than the old-fashioned open detector, the crystal itself and the cat-whisker being enclosed in a neat molded bakelite case.” It could be adjusted by means of a “little red button” on the outside.