Operating mode electrical circuit, at which the current and voltage at the circuit input are in phase is called resonance . In this case, the equivalent resistance of the entire circuit will be active. In circuits consisting of resistive, inductive and capacitive elements, a distinction is made between voltage resonance and current resonance.

Voltage resonance

Voltage resonance can occur in a circuit with inductive and capacitive elements connected in series. Let's consider a diagram of a series connection of a resistor, inductance and capacitance (Fig. 6.1).

U X = U L – U C– positive, and the phase angle between current and voltage φ> active-inductive .

2. Let the inductive reactance be less than the capacitive reactance X L< X C . Then the inductive voltage will become less than the capacitive voltage U L< U C, since the current flows through the elements is the same, and the voltage is proportional to the current and resistance. The vector diagram will look like (Fig. 6.3).

Reactive voltage component U X = U L – U C– negative, and the phase angle between current and voltage φ < 0. This nature of the circuit is active-capacitive .

3. Let X L = X C, in this case the inductive and capacitive voltages are equal in magnitude U L= U C. Since they are always opposite in phase, they completely compensate each other, hence the reactive component U X= U L – U C= 0. The total voltage will be active and in phase with the current φ = 0, therefore, there is a voltage resonance in the circuit. The vector diagram for this case is shown in Fig. 6.4.

From the above it follows that the condition under which voltage resonance occurs is the equality of inductive and capacitive reactances.

From expression (6.1) it follows that at resonance the total resistance of the circuit is active.

Voltage resonance can be achieved by selecting three parameters:

1) changing the frequency of the oscillatory circuit, L,C= const;

2) changing the inductance of the circuit , , C = const;

3) changing the capacitance of the oscillatory circuit , , L= const.

Moreover, all three parameters are interconnected.

From the condition we get: , from here:

Frequency ω 0 determined from such a condition is called resonant.

If the voltage at the circuit terminals and the active resistance of the circuit R do not change, then the current at resonance has a maximum value

, because .

If the reactance exceeds the active resistance at resonance:

, ,

then the voltages at the terminals of the coil and capacitor can significantly exceed the voltage at the input of the circuit.

The excess of voltage on reactive elements over the voltage at the input is usually characterized by the value

,

called the characteristic or characteristic impedance of the circuit. The characteristic impedance is numerically equal to the inductive or capacitive reactance on resonant frequency.

The ratio of the excess voltage at the terminals of inductive and capacitive reactances over the input is determined by the ratio of the voltage on the reactive element to the voltage at the input of the circuit at the resonant frequency:

This value is called the circuit quality factor.

The reciprocal of the quality factor

called loop attenuation.

The selective properties of the oscillatory circuit are determined by its quality factor. The higher the quality factor of the circuit, the narrower the resonance curve will be (Fig. 6.5).

The selectivity of the circuit is characterized by the passband. Bandwidth is the range of frequencies for which the current is attenuated by no more than a factor of the maximum value

.

The bandwidth can be determined by the formula

Let's consider the resonant curves of current and voltage (Fig. 6.6).

With constant circuit parameters and constant input voltage, the current will be determined by the expression

.

Let's consider this expression at reference points: ; . At zero frequency, the current in the circuit will be constant, the magnitude of the current is , since the capacitor does not pass D.C., at the resonant frequency the current is maximum - this is a sign of voltage resonance. At high frequencies the current flows as the coil resistance becomes equal.

The voltage across the inductance is proportional to the frequency, therefore, at zero frequency, the voltage across the inductance is . When all the voltage supplied from the source is applied to the inductance, and .

The voltage across the capacitance is inversely proportional to the frequency, therefore, when all the voltage is applied to the capacitor. At , since capacitive reactance is equal to zero.

At the resonant frequency, the inductive and capacitive voltages are equal.

The voltage across the resistive element is proportional to the current and, therefore, repeats the shape of the current curve at and , at .

Let us consider the energy relationships at resonance.

The instantaneous power values ​​at the terminals of the coil and capacitor are determined by the expressions:

;

.

Since at resonance, these powers at any moment of time are equal and opposite in sign. This means that energy is exchanged between the magnetic field of the coil and the electric field of the capacitor, but there is no exchange between the source and the reactive elements, since

And ,

that is, the total energy of the electric and magnetic fields remains constant. Energy transfers from the capacitor to the coil during a quarter period, when the voltage across the capacitor decreases and the current increases. During the next quarter period, energy moves from the coil to the capacitor. The energy source powers only the active resistance.

Current resonance

Resonance in an ideal circuit

Current resonance occurs when inductance and capacitance are connected in parallel. To generalize the analyses, we will include an active resistance in the circuit parallel to the inductance and capacitance (Fig. 6.7).

According to Kirchhoff's first law, we can write:

.

Let's write this expression in complex form:

,

Where , , .

Let's take the voltage out of the bracket and get

.

The condition for current resonance is the equality of inductive and capacitive conductivities:

.

The vector diagram for the resonance mode is shown in Fig. 6.8. If the inductive and capacitive conductivities are equal, the currents will also be equal. Directed in antiphase, these currents cancel each other out, only the active component of the current remains in the circuit, and the total current will be in phase with the voltage. Therefore, resonance is called current resonance.

The total current in the circuit can be represented as,

Where – total complex conductivity, the modulus of which is equal to

.

Taking into account the resonance condition, we obtain that, that is, the conductivity of the circuit is minimal, therefore, the current will be minimal - this is a sign of current resonance.

From the resonance condition we obtain an expression for the resonant frequency

That is, as with voltage resonance, current resonance can be achieved by changing one of three parameters ω , L, C.

Resonance in a real circuit

A real coil and a real capacitor have not only reactive, but also active resistance. The coil is the resistance of the winding, the capacitor is the resistance to leakage currents. In this case, with a high quality factor of the coil or capacitor, the active resistance may turn out to be a function of frequency.

By the quality factor of a coil we mean the ratio of its inductive reactance to its active reactance.

The quality factor of a capacitor is the ratio of its capacitance to its active resistance

.

Consider a circuit containing a real coil and capacitor, shown in Fig. 6.9.

The condition for resonance of currents in such a circuit is that the reactive conductivity is zero.

The complex conductivity of a circuit can be expressed through the complex resistances of the branches:

Knowledge of physics and the theory of this science is directly related to housekeeping, repairs, construction and mechanical engineering. We propose to consider what resonance of currents and voltages in a series RLC circuit is, what the main condition for its formation is, as well as the calculation.

What is resonance?

Definition of the phenomenon by TOE: electrical resonance occurs in an electrical circuit at a certain resonant frequency, when some parts of the resistance or conductivity of the circuit elements cancel each other. In some circuits, this occurs when the impedance between the input and output of the circuit is almost zero and the signal transfer function is close to unity. In this case, the quality factor of this circuit is very important.

Signs of resonance:

1. The components of the reactive branches of the current are equal to each other IPC = IPL, antiphase is formed only when the net active energy at the input is equal;
2. The current in individual branches exceeds the entire current of a particular circuit, while the branches are in phase.

In other words, resonance in an AC circuit implies a special frequency, and is determined by the values ​​of resistance, capacitance and inductance. There are two types of current resonance:

1. Consistent;
2. Parallel.

For series resonance, the condition is simple and is characterized by minimal resistance and zero phase, it is used in reactive circuits, and it is also used in branched circuits. Parallel resonance or the concept of an RLC circuit occurs when the inductive and capacitive inputs are equal in magnitude but cancel each other out since they are at an angle of 180 degrees from each other. This connection must be constantly equal to the specified value. It has received wider practical application. The sharp minimum impedance that it exhibits is beneficial for many electrical household appliances. The sharpness of the minimum depends on the resistance value.

An RLC circuit (or circuit) is electrical diagram, which consists of a resistor, inductor, and capacitor connected in series or parallel. The parallel oscillating circuit RLC gets its name from the abbreviation of physical quantities representing resistance, inductance and capacitance, respectively. The circuit forms a harmonic oscillator for the current. Any oscillation of the current induced in the circuit fades over time if the movement of the directed particles is stopped by the source. This resistor effect is called attenuation. The presence of resistance also reduces the peak resonant frequency. Some resistance is unavoidable in real circuits, even if a resistor is not included in the circuit.

Application

Almost all power electrical engineering uses just such an oscillatory circuit, say, a power transformer. The circuit is also necessary for setting up the operation of a TV, capacitive generator, welding machine, radio receiver; it is used by the “matching” technology of television broadcast antennas, where you need to select a narrow frequency range of some of the waves used. The RLC circuit can be used as a bandpass filter, notch filter, for low or high frequency distribution sensors.

Resonance is even used in aesthetic medicine (microcurrent therapy) and bioresonance diagnostics.

Principle of current resonance

We can make a resonant or oscillating circuit at its natural frequency, say, to power a capacitor, as the following diagram demonstrates:

Circuit for powering a capacitor

The switch will be responsible for the direction of vibration.

Circuit: resonant circuit switch

The capacitor stores all the current at the moment when time = 0. Oscillations in the circuit are measured using ammeters.

Scheme: the current in the resonant circuit is zero

Directed particles move in right side. The inductor receives current from the capacitor.

When the polarity of the circuit returns to its original form, the current returns to the heat exchanger.

Now the directed energy goes back into the capacitor, and the circle repeats again.

In real mixed circuit circuits there is always some resistance which causes the amplitude of the directed particles to grow smaller with each circle. After several changes in the polarity of the plates, the current drops to 0. This process is called a damped sine wave signal. How quickly this process occurs depends on the resistance in the circuit. But the resistance does not change the frequency of the sine wave. If the resistance is high enough, the current will not fluctuate at all.

The AC designation means that the energy leaving the power supply fluctuates with certain frequency. An increase in resistance helps to reduce the maximum size of the current amplitude, but this does not lead to a change in the resonance frequency. But an eddy current process can form. After its occurrence, network interruptions are possible.

Resonant circuit calculation

It should be noted that this phenomenon requires very careful calculation, especially if a parallel connection is used. In order to avoid interference in technology, you need to use various formulas. They will be useful to you for solving any problem in physics from the corresponding section.

It is very important to know the power value in the circuit. The average power dissipated in a resonant circuit can be expressed in terms of rms voltage and current as follows:

R av = I 2 contact * R = (V 2 contact / Z 2) * R.

At the same time, remember that the power factor at resonance is cos φ = 1

The resonance formula itself has the following form:

ω 0 = 1 / √L*C

Zero impedance at resonance is determined using the following formula:

F res = 1 / 2π √L*C

The resonant frequency of oscillation can be approximated as follows:

F = 1/2 r (LC) 0.5

Where: F = frequency

L = inductance

C = capacity

Generally, a circuit will not oscillate unless the resistance (R) is low enough to satisfy the following requirements:

R = 2 (L/C) 0.5

To obtain accurate data, you should try not to round the obtained values ​​due to calculations. Many physicists recommend using a method called vector diagram of active currents. With proper calculation and configuration of devices, you will get good savings in alternating current.

Resonance is a mode of a passive circuit containing inductors and capacitors in which its input reactance or its input reactance is zero. At resonance, the current at the input of the circuit, if it is different from zero, is in phase with the voltage.

Consider a series connection of resistance, inductance and capacitance (Fig. 3-8). Such a circuit is often called a series circuit. For it, resonance occurs when or, i.e.

When the values ​​of voltages opposite in phase on the inductance and capacitance are equal (Fig. 3-11, b), therefore the resonance in the circuit under consideration is called voltage resonance.

The voltages across the inductance and capacitance at resonance can significantly exceed the voltage at the circuit terminals, which is equal to the voltage across the active resistance. The total resistance of the circuit at a minimum: , and the current at a given

voltage U reaches its highest value. In the theoretical case, at the total resistance of the circuit in the resonance mode is also zero, and the current at any finite value of the voltage U is infinitely large. In the same way, the voltages on inductance and capacitance are infinitely large.

It follows from the condition that resonance can be achieved by changing either the source voltage frequency or the circuit parameters - inductance or capacitance. The angular frequency at which resonance occurs is called the resonant angular frequency

Inductive and capacitive reactance at resonance

The value is called the characteristic impedance of the circuit or circuit.

The ratio of the voltage across an inductance or capacitance to the voltage applied to the circuit at resonance

called the circuit quality factor or resonance coefficient. The resonance coefficient indicates how many times the voltage across the inductance or capacitance at resonance is greater than the voltage applied to the circuit: if . The name “quality factor” of the circuit will be explained in the next paragraph.

To understand the energy processes during resonance, let us determine the sum of the energies of the magnetic and electric fields of the circuit. Let the current in the circuit be . Then the voltage across the capacitance

Total energy

and therefore

that is, the sum of the energies of the magnetic and electric fields does not change over time. A decrease in the electric field energy is accompanied by an increase in the magnetic field energy and vice versa. Thus, there is a continuous transition of energy from the electric field to the magnetic field and back.

The energy supplied to the circuit from the power source is completely converted into heat at any given time. Therefore, for a power supply, the entire circuit is equivalent to one active resistance.

The name “resonance” for the considered circuit mode is borrowed from the theory of oscillations. As is known, resonance is a process of forced oscillations with a frequency at which the intensity of oscillations, other things being equal, is maximum. But the intensity of the oscillatory process can be characterized by various manifestations, the maxima of which are observed at different frequencies. Therefore, it is necessary to agree on the criterion of resonance.

Charges oscillate in an electrical circuit. One could take as a resonance criterion the maximum amplitude value of the charge on the capacitor, which corresponds to the maximum amplitude of the voltage on the capacitor. This criterion determines the amplitude resonance. For the resonance criterion adopted at the beginning of the paragraph, the current at resonance is in phase with the applied voltage, this is the so-called phase resonance. In the scheme under consideration (Fig. 3-8), phase resonance occurs at the maximum speed of movement of oscillating charges or maximum current.

If a charged capacitor is connected to an inductance coil, then in such a circuit, with a sufficiently low resistance of the coil, a process of damped oscillations of voltage and current is observed. The frequency of these vibrations is called the frequency of natural or free vibrations. Note that the frequencies at which phase and amplitude resonances are observed do not coincide with the frequency of natural oscillations (they coincide only in the theoretical case when the circuit resistance is zero). The resonance criterion adopted here is also applicable in the case when natural oscillations are impossible in the circuit due to high resistance.

Resonance is one of the most common in nature. Resonance can be observed in mechanical, electrical and even thermal systems. Without resonance, we would not have radio, television, music, or even swings on playgrounds, not to mention the most effective diagnostic systems used in modern medicine. One of the most interesting and useful types of resonance in an electrical circuit is voltage resonance.

Elements of a resonant circuit

The phenomenon of resonance can occur in a so-called RLC circuit containing the following components:

• R - resistors. These devices, which belong to the so-called active elements of the electrical circuit, convert electrical energy into thermal energy. In other words, they remove energy from the circuit and convert it into heat.
• L - inductance. Inductance in electrical circuits is analogous to mass or inertia in mechanical systems. This component is not very noticeable in an electrical circuit until you try to make any changes to it. In mechanics, for example, such a change is a change in speed. In an electrical circuit - a change in current. If for any reason it occurs, the inductance counteracts this change in circuit mode.
• C is the designation for capacitors, which are devices that store electrical energy in the same way that springs store Inductance concentrates and stores magnetic energy, while a capacitor concentrates charge and thereby stores electrical energy.

The concept of a resonant circuit

The key elements of a resonant circuit are inductance (L) and capacitance (C). A resistor tends to dampen oscillations, so it removes energy from the circuit. When considering the processes occurring in an oscillatory circuit, we temporarily ignore it, but we must remember that, like the friction force in mechanical systems, electrical resistance in circuits cannot be eliminated.

Voltage resonance and current resonance

Depending on the method of connecting the key elements, the resonant circuit can be serial or parallel. When a series oscillating circuit is connected to a voltage source with a signal frequency that coincides with its own frequency, under certain conditions a voltage resonance occurs in it. Resonance in an electrical circuit with parallel-connected reactive elements is called current resonance.

Natural frequency of the resonant circuit

We can make the system oscillate at its own frequency. To do this, you first need to charge the capacitor, as shown in the top left picture. When this is done, the key is moved to the position shown in the same figure on the right.

At time "0", all electrical energy is stored in the capacitor, and the current in the circuit is zero (figure below). Note that the top plate of the capacitor is positively charged and the bottom plate is negatively charged. We cannot see the oscillations of electrons in a circuit, but we can measure the current with an ammeter, and use an oscilloscope to track the pattern of current versus time. Note that T on our graph is the time required to complete one oscillation, which in electrical engineering is called the “oscillation period.”

The current flows clockwise (picture below). Energy is transferred from the capacitor to At first glance it may seem strange that inductance contains energy, but this is similar to the kinetic energy contained in a moving mass.

The energy flows back into the capacitor, but notice that the polarity of the capacitor has now reversed. In other words, the bottom plate now has a positive charge and the top plate has a negative charge (picture below).

Now the system has completely reversed, and energy begins to flow from the capacitor back into the inductance (figure below). Eventually the energy returns completely to its starting point and is ready to begin the cycle again.

The oscillation frequency can be approximated as follows:

• F = 1/2π(LC) 0.5,

where: F - frequency, L - inductance, C - capacitance.

The process considered in this example reflects the physical essence of stress resonance.

Stress Resonance Study

In real LC circuits there is always a small resistance, which reduces the increase in current amplitude with each cycle. After several cycles, the current decreases to zero. This effect is called "sine wave damping". The rate at which the current decays to zero depends on the resistance value in the circuit. However, resistance does not change the oscillation frequency of the resonant circuit. If the resistance is high enough, sinusoidal oscillations in the circuit will not occur at all.

Obviously, where there is a natural frequency of oscillations, there is the possibility of excitation of a resonant process. We do this by including a power supply (AC) in the series circuit, as shown in the figure to the left. The term "variable" means that the output voltage of the source fluctuates at a certain frequency. If the frequency of the power supply coincides with the natural frequency of the circuit, voltage resonance occurs.

Conditions of occurrence

Now we will consider the conditions for the occurrence of voltage resonance. As shown in the last picture, we have returned the resistor to the circuit. In the absence of a resistor in the circuit, the current in the resonant circuit will increase to a certain maximum value, determined by the parameters of the circuit elements and the power of the power source. Increasing the resistance of the resistor in the resonant circuit increases the tendency for the current to attenuate in the circuit, but does not affect the frequency of the resonant oscillations. As a rule, the voltage resonance mode does not occur if the resistance of the resonance circuit satisfies the condition R = 2(L/C) 0.5.

Using voltage resonance to transmit a radio signal

The phenomenon of stress resonance is not only a very interesting physical phenomenon. It plays an exceptional role in wireless communications technology - radio, television, cellular telephony. Transmitters used for wireless transmission information necessarily contain circuits designed to resonate at a specific frequency for each device, called the carrier frequency. With the help of a transmitting antenna connected to the transmitter, it emits at a carrier frequency.

An antenna at the other end of the transmit-receive path receives this signal and supplies it to a receiving circuit designed to resonate at the carrier frequency. Obviously, the antenna receives many signals at different frequencies, not to mention background noise. Due to the presence at the input of a receiving device tuned to the carrier frequency of the resonant circuit, the receiver selects the only correct frequency, eliminating all unnecessary ones.

After detecting an amplitude-modulated (AM) radio signal, the low-frequency signal (LF) extracted from it is amplified and fed to a sound-reproducing device. This simplest form of radio transmission is very sensitive to noise and interference.

To improve the quality of received information, other, more advanced methods of radio signal transmission, which are also based on the use of tuned resonant systems, have been developed and are successfully used.

Or FM radio solves many of the problems of amplitude modulated radio transmission, but at the cost of significantly increasing the complexity of the transmission system. On FM radio system sounds in the electronic path are converted into small changes in the carrier frequency. The piece of equipment that performs this conversion is called a "modulator" and is used with the transmitter.

Accordingly, a demodulator must be added to the receiver to convert the signal back into a form that can be reproduced through a loudspeaker.

Other Uses of Voltage Resonance

Voltage resonance as a fundamental principle is also incorporated in the circuit design of numerous filters, widely used in electrical engineering to eliminate harmful and unnecessary signals, smooth out ripples and generate sinusoidal signals.

Let's start with basic definitions.

Definition 1

Resonance is a phenomenon in which the oscillation frequency of any system is increased by fluctuations in an external force.

Forced vibrations, the source of which is an external force, increase even those vibrations whose amplitude is quite small. The maximum resonance with the greatest amplitude is possible precisely when the frequencies of the external influence and the system under consideration coincide.

An example of resonance is the rocking of a bridge by a company of soldiers. The step frequency of the soldiers, which is an example of forced oscillations in relation to the bridge, is synchronized and can coincide with the natural frequency of oscillations of the bridge. As a result, the bridge may collapse.

Electrical resonance in physics is considered one of the most common physical phenomena in the world, without which it would be impossible, for example, television and diagnostics using medical devices.

Some of the most useful types of resonance in an electrical circuit are:

• current resonance;
• voltage resonance.

The occurrence of resonance in an electrical circuit

Note 1

The occurrence of resonance in an electrical circuit is facilitated by a sharp increase in the amplitude of stationary natural oscillations of the system, provided that the frequency of the external side of the influence coincides with the corresponding oscillatory resonant frequency of the system.

The $RLC$ circuit represents an electrical circuit with elements (resistor, inductor, capacitor) connected in series or parallel. The name $RLC$ consists of simple characters electrical elements: resistance, capacitance, inductance.

The vector diagram of a sequential $RLC$ circuit is presented in one of three variations:

• capacitive;
• active;
• inductive.

In the last variation, voltage resonance occurs under the condition of zero phase shift, and the values ​​of inductive and capacitive reactance coincide.

Voltage resonance

At serial connection active element $r$, capacitive $C$ and inductive $L$ in alternating current circuits, a physical phenomenon such as voltage resonance may occur. The oscillations of the voltage source in this case will be equal in frequency to the oscillations of the circuit. At the same time, both the usefulness (for example, in radio engineering) of this phenomenon and the negative consequences (for high-power electrical installations) are known, for example, with a sharp surge in voltage in the systems, a malfunction or even a fire may occur.

Voltage resonance is usually achieved in three ways:

• selection of coil inductance;
• selection of capacitor capacity;
• selection of angular frequency $w_0$.

In this case, all values ​​of capacitance, frequency and inductance are determined using the formulas:

$L_0 = \frac(1)(w^2C)$

$C_0 = \frac(1)(w^2L)$

The frequency $w_0$ is considered resonant. Provided that both the voltage and active resistance $r$ in the circuit remain constant, the current strength at voltage resonance in it will be maximum and equal to:

This assumes that the current is completely independent of the reactance of the circuit. In a situation where the reactance $XC = XL$ exceeds the active resistance $r$ in value, a voltage will appear at the coil and capacitor terminals that significantly exceeds the voltage at the circuit terminals.

The excess voltage ratio at the terminals of the capacitive and inductive element relative to the network is determined by the expression:

$Q = \frac(U_c0)(U)$

The value $Q$ characterizes the resonant properties of the circuit, and is called the quality factor of the circuit. Also, resonant properties are characterized by the value $\frac(1)(Q)$, that is, the damping of the circuit.

Resonance of currents through reactive elements

Resonance of currents appears in electrical circuits of alternating current circuits under the condition of parallel connection of branches with different reactances. In the resonant mode of currents, the reactive inductive conductivity of the circuit will be equivalent to its own reactive capacitive conductivity, i.e. $BL = BC$.

Circuit oscillations, the frequency of which is certain value, in this case, coincide in frequency with the voltage source.

The simplest electrical circuit in which we observe current resonance is considered to be a circuit with parallel connection capacitor with inductor.

Since the reactivity resistances are equal in magnitude, the amplitudes of the currents $I_c$ and $I_u$ will be the same and can reach their maximum amplitude. Based on Kirchhoff's first law, $IR$ is equal to the source current. The source current, in other words, flows only through the resistor. When considering a separate parallel circuit $LC$, at the resonant frequency its resistance turns out to be infinitely large: $ZL = ZC$. When a harmonic mode with a resonant frequency is established, the circuit is observed to provide a certain steady-state oscillation amplitude with a source, and the power of the current source is spent exclusively on replenishing losses in the active resistance.

Thus, the impedance of a series $RLC$ circuit turns out to be minimal at the resonant frequency and equal to the active resistance of the circuit. At the same time, the impedance of a parallel $RLC$ circuit is maximum at the resonant frequency and is considered equal to the leakage resistance, which is actually also the active resistance of the circuit. In order to ensure conditions for resonance of current or voltage, it is necessary to check the electrical circuit to predetermine its complex resistance or conductivity. In addition, its imaginary part must be equal to zero.

Application of resonance phenomenon

A good example of the use of the resonant phenomenon is the electrical resonant transformer, developed by Nikola Tesla back in 1891. The scientist conducted experiments on different configurations, consisting of a combination of two, and often three, resonant electrical circuits.

Note 2

The term "Tesla coils" is applied to high-voltage resonant transformers. The devices are used to produce high voltage, alternating current frequency. A conventional transformer is necessary for efficient transfer of energy from the primary to the secondary winding, a resonant one is used for temporary storage of electricity.

The device is responsible for controlling the air core of a resonantly tuned transformer in order to obtain high voltage at low current strengths. Each winding has a capacitance and functions as a resonant circuit. To produce the highest output voltage, the primary and secondary circuits are tuned into resonance with each other.