Marconiphone crystal-valve radio receiver, 1923.

This type RB10 crystal set is typical of the type available to domestic buyers in the 1920s. At the time, ready-made valve radio sets complete with a loudspeaker were expensive items. Constructing the set at home lowered the cost somewhat, but a more affordable option was this type of crystal set, which was listened to through a pair of headphones. The working instructions for the set are on the inside of the lid.