A Makeshift Crystal Radio Output Transformer

Discussion in 'Wireless & RF Design' started by vu2nan, Sep 9, 2015.

  1. vu2nan

    Thread Starter Member

    Sep 11, 2014
    This project was part of my initial attempts at homebrewing an output transformer for my Loudspeaking Crystal Radio.

    An air-core crossover network inductor and a ferrite-core one (from the junkbox) appeared suitable as the primary and secondary windings of the transformer.

    An Air-core & a Ferrite Core Crossover Inductor

    The large number of turns of the air-core inductor as primary and the small number of the ferrite one as secondary would give a step-down ratio. With luck, the open ferrite core would enable reasonable coupling.

    Simple coupling of the two inductors

    Testing was simple, with the air-core inductor hooked up to the crystal radio and the ferrite-core one (placed within) connected to the speaker.

    The result was encouraging enough for further attempts which culminated in a proper Crystal Radio Output Transformer.