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I hope this comment helps. Mine didn't worked at first but after some CRITICAL fixes: 1) Bigger toroidal and thinner wires. And MOST IMPORTANT 2) The transistor wired as shown will NOT work in many cases because Base, Collector and Emitter are NOT in the same place. You need to know where the BCE are and is recommended to see a diagram for this circuit. I used both ferrite core and transistor from a dead CFL and did the test with a "dead" 1.5v battery and a UV LED. My transistor was a 13002.