A resonant transformer is often referred to as a Tesla transformer or Tesla coil. The device was patented by the United States of America on September 22nd, one thousand eight hundred and ninety-six, under the name "Apparatus for the production of electric current of the highest potential and frequency." As the name implies, this device was invented by the famous scientist Nikola Tesla.
The simplest resonant transformer consists of two coils without an aggregate core. The primary winding has only a few turns (from three to ten). However, this winding is wound with a thick electrical wire. The secondary winding of a device such as a resonant transformer is often referred to as high voltage. It has many more turns than the primary one (up to several hundred). However, it is wound with a thinner electrical wire.
As a result of such a simple design, the resonant transformer has a CT (transformation ratio), which exceeds the value of the ratio of turns of the secondary winding to the primary by several tens of times. The output voltage on such a transformer canexceed one million volts. Based on this design, devices such as resonant generators have already been developed. Also, such electric machines are often used as demonstration devices. Due to the huge voltage at the resonant frequency, such a device is able to create electrical discharges right in the air. And their length can be truly impressive. Depending on the input voltage, the length of the discharge can be up to several tens of meters. The very design of such an electrical installation as the Tesla resonant transformer is quite simple and uncomplicated. It consists of coils (two - secondary and primary), a spark gap (aka a breaker). The composition of this device necessarily includes capacitors (both for compensation and for charge accumulation). Toroidal coils and terminals are often used (to create a device such as a resonant transformer with output power amplification).
As mentioned earlier, the primary coil traditionally has a few turns, and the secondary coil has several hundred. Moreover, a flat primary coil design, either horizontal, cylindrical, conical, or vertical, is common. Also, in a device such as a resonant transformer, there is no ferromagnetic core (unlike power or instrument transformers). Thus, it has much less mutual inductance between the windings of both coils than conventional traditional transformers (inductive coupling amplification is justachieved due to the presence of a ferromagnetic core).
Thus, the capacitor and the primary coil constitute an oscillatory circuit. This includes a non-linear component - a spark gap, which consists of two electrodes with a gap. The secondary coil also forms a similar circuit, but instead of a capacitor, a toroid is used here. It is the presence of two connected oscillatory circuits that is the whole basis of the operation of such a device as the Tesla resonant transformer.
