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.
_______________________________
