Crystal Radio Output Transformer

The large size of the power transformer, used as an output transformer for my 'Loudspeaker 
Crystal Radio', was good enough reason to attempt homebrewing a relatively small one.

A search through the junk box yielded a 47mm diameter, Siemens N22 pot core set.

Pot Core used for Crystal Radio Output Transformer

Winding was for an autotransformer, having 500 turns of 30 SWG enamelled copper wire (the maximum number that could be accommodated), with output taps at 50 and 100 turns.

Crystal Radio Output Transformer - winding scheme

The 50-turn tap was to match the existing 3 Ω speaker and the100-turn one a provision for speakers of higher impedance.

A small PCB, also from the junk box, provided termination points for the winding.

Crystal Radio Output Transformer- inside view

A couple of reworked white plastic cosmetic jar bodies lent themselves as enclosure halves.

Crystal Radio Output Transformer

Tests indicated that, inspite of its small size, the output transformer's performance is comparable, though not equal, to that of the power transformer.

Related post: Makeshift Crystal Radio Output Transformer

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