This project was part of my initial attempts at homebrewing an output transformer for my
'Loudspeaker Crystal Radio'.
An air-core crossover network inductor and a ferrite-core one (from the junk box) appeared suitable as the primary and secondary windings of the transformer.
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| 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.
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| 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'.
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