Crystal Radio Output Transformer

Discussion in 'Wireless & RF Design' started by vu2nan, Sep 1, 2015.

  1. vu2nan

    Thread Starter Member

    Sep 11, 2014
    Crystal Radio Output Transformer

    The large size of the power transformer, used as an output transformer for my Loudspeaking 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.


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


    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.


    A couple of white plastic cosmetic jars were reworked to form the enclosure, giving the transformer a presentable appearance.


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


    Last edited: Sep 1, 2015
    .W4GNS and be80be like this.
  2. be80be

    Senior Member

    Jul 5, 2008
    Nice Job looks really good.