The toroid transformer is the heart of the system as it'll be stepping up the low voltage of the joule thief.

The first step is to take some magnet wire and wind 8 turns on the toroid. Then wind another, identical one right after it. Solder them together in the middle. That's the joule thief coil.

The next step is to wire the high voltage coil. Take magnet wire and wind as many turns as possible. More turns means higher output voltage.

I found out electrical tape is a great way of holding wires in place when winding. It also holds the coil together.

Wire the positive pin of the coin cell holder to the switch. The other part goes to the center-tap of the joule thief coil. The 'high' end of the joule thief coil goes to the base of the transistor through a 1k resistor and the 'low' end goes to the collector. The emitter is connected to the minus pin.

Connect the high voltage coil ends to the AC terminals of your rectifier bridge, and the + and - leads to the capacitor.

Then you can wire the capacitor to your victim LED via a switch.

Be careful! The circuit isn't dangerous when loaded by a capacitor, but unloaded it's capable of producing 200V spikes. For your own safety, always load the high voltage part with a capacitor or a small value resistor (100 Ohms) to prevent electrocution.

Start the charging procedure by switching the circuit on. If the voltage on the capacitor doesn't start rising rightaway, wait for a few seconds for the joule thief to start oscillating.

Wait 10-25 minutes for the capacitor to charge up. Be patient until the voltage is around 22 V.

Switch off the joule thief and switch on the LED. Enjoy the destruction.