Tesla coil Wireless Power Transmission: Slayer Exciter Circuit

Tesla coil is an electrical resonant transformer circuit invented by Nikola Tesla. It is a form of induction coil for producing high voltage, high-frequency alternating currents. Nikola Tesla in 1891 demonstrated wireless power transmission by lighting light bulbs from across a stage. A Tesla coil can be in the form of a Switched or Solid State Tesla Coil (SSTC). In this mode, a transistor is used to switch pulses of current from a DC power supply through the primary coil.

The circuit developed in this tutorial is called slayer exciter. A slayer exciter is a small SSTC coil. A Slayer Exciter is an air-cored transformer that steps up a very low DC voltage to a very high AC voltage. This creates an electromagnetic field around the coil that is capable of lighting up fluorescent and neon light bulbs.

The coil will wirelessly light up flash frequency tube, neon and LED lights. 12V input voltage generates an arc about 2mm. The circuit includes the following components:

1. PVC plastic
2. Electrolytic capacitor (2.2uF, 100V)
3. Resistor (15MOhm)
4. 12VDC Power Socket
5. Heat sink
6. Transistor (BD243C)
7. Primary coil
8. Secondary coil
9. Green LED

The circuit is shown below:

The soldered circuit is shown below:

The Slayer Exciter circuit uses a clever feedback solution. Current flows through the resistor, following the base-emitter (BE) path and back to the power supply. It closes the circuit and electricity is allowed to flow through the primary coil.  The BE current brings the transistor into minimum resistance state. This is because the Base receives little current as a result of the 150MOhm resistor. However, electricity likes to take the path of least resistance so when the electricity is allowed to flow from the collector to the emitter (~0 ohm resistance) it will stop flowing to the base because there is 150MOhm of resistance there. When the electricity stops flowing to the base, the base will open up the circuit again until the resistor offers less resistance than the Collector-Emitter path. This cycle repeats itself many times a second.

A large current flows from the 12VDC power supply through the primary coil with 3 turns, and then through the collector to emitter path and back to the supply. The difference in current between the BE path (low current) and CE path (high current) creates a changing magnetic field in the primary coil which creates a changing magnetic field in the secondary coil which again creates a changing voltage (AC Voltage) in the secondary coil.