80 years ago, this dad was helping his kids put together crystal sets from the pages of Popular Mechanics, January 1936.  That issue included plans for two sets that were particularly selective.  The magazine also pointed out that the audio quality of a crystal set was particularly good, despite the requirement for high-impedance headphones.

The first set, shown here, was a fairly typical design employing a tapped coil and variable condenser.   The second set, shown below, was a simpler set but with an interesting design.  It was built in a hinged box with a honeycomb coil inside the box, with another in the lid.  To tune the set, it was placed on end, and the lid was opened and closed to tune the band.

The article noted that either set could be built for a few cents.  The most expensive component was the headphones, which started at 98 cents.

All of the parts, or suitable modern substitutions, for both of these sets are readily available.  For help on tracking them down, you can visit my crystal set parts page.

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