Posted on May 11, 2017 7140
Those coils are no more than two aluminum foils taken from the guts of a large electrolitic capacitor and winded on the ferrite core with a dielectric insulator between them, Plastic film in that case. Each Coil/capacitor has 60 turns of foil pairs. Inductunce should be around 0.53mH and the forming capacitance 48μF for each finished coil.
So each coil/capacitor has four terminal ends and not two as a regular capacitor has. Two at start and two at the end. The circuit use three of these coils for the output. Try to make them as identical as they can be. Capacitors may need to be changed according to the forming capacitance and inductunce of your coils. The two variable capacitors and the variable resistor are needed to tune the circuit to resonate.
The earth connection must be good and must be completely seperate from the house mains earth. Start with low power, put 3 volts at the joule thief and gradualy increase the voltage with the load connected.
Tune first the variable resistor for best output, and then tune the variable capacitors to match the frequencies. Be very carefull while you playing with this unit. You should be expert in high voltage if you decide to experiment with this circuit. If tuned properly, its output can shock you very badly or even kill you.