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Aug 6 2019

Wireless Electricity?What is a Tesla Coil?


Article Core : What is a Tesla Coil and How to Make a Simple Tesla Coil




Classification of tesla coils


Tesla coil calculation formula


12 Volt ultra simple tesla coil manufacturing process


Tesla coil

Tesla coil is a distributed parameter high-frequency series resonant transformer proposed by Nikola tesla,a physicist wizard in history. It can obtain a high frequency voltage of millions of volts. It has a two-stage booster coil which made it can take a household 220V voltage up to tens or even hundreds of thousands of volts and discharge it through a discharge terminal. To put it more colloquially, it is an artificial lightning-maker. Because of the high voltage, the sparks produced by the discharge are like small lightning bolts. There are tesla coil fans all over the world, who have made all kinds of devices to create dazzling artificial lightning, which is very beautiful. On the other hand, the tesla coil contains an LC oscillation circuit, so the alternating current generated by the discharge terminal has a high frequency.

Classification of tesla coils

In fact, there are many types of tesla coils, because according to different design concepts, tesla coils can produce different effects. Different wiring levels can produce different performance, and the amount of energy can also have different effects. Generally, tesla coils have the following types.

1. SGTC(Spark Gap Tesla Coil)


The "tesla coil" invented by nikola tesla himself belongs to SGTC. Due to its simple structure and principle, it is also the beginning tesla coil for beginners.


IGBT tube, which is a trigger diode, replaces the traditional spark gap to eliminate the spark noise.

3. SSTC(Solid State Tesla Coil)

Generally speaking, it is a single-resonance electronic switch tesla coil. The primary does not occur series resonance, but only provides the frequency that can satisfy the series resonance of secondary LC, so that the secondary coil occurs series resonance. The primary current is the excitation source voltage divided by the AC impedance.

Advantages: low noise, high efficiency and long life.

Disadvantages: the primary coil provides limited excitation power to the secondary coil, and the arc is not long.

4. ISSTC(Interrupted SSTC)

At the same output power, the arc of SSTC is clustered and obviously not as spectacular as SGTC. At this moment,an arc extinguisher can be added to mimic the work of SGTC.

5. DRSSTC(Dual Resonant SSTC)

DRSSTC essence belongs to a series resonant inverter. For SSTC, due to the series resonance of the primary coil, excitation source voltage to the voltage at the ends of the primary coil inductance of Q times, harmonic impedance Z (R) factor of low, so the primary resonance of the current large (resonance current is equal to the resonant voltage divided by the resonant impedance). At this time the excitation power offered to secondary coil will be very big, and SSTC will not be an order of magnitude. Compared with SSTC, the primary coil of SSTC cannot provide enough excitation power to the secondary coil, so the lightning spectacular degree generated by SSTC is not as spectacular as the spark-gap tesla coil of the same power level.

The primary coil of DRSSTC not only satisfies the condition of series resonance of inductance and distributed capacitance of the secondary coil, but also provides sufficient excitation power to the secondary coil, so the arc length of DRSSTC will be very long.

Advantages: compared with SGTC, no spark gap pollution, strong controllability, availability of putting music, high efficiency, long life.

6. QCWDRSSTC(Quasi Continuous Wave DRSSTC)

7. CWDRSSTC(Continuous Wave DRSSTC)

It is proved by experiments that the arc of continuous mode (CW) tesla coil is not long and in a cluster shape if the power is exerted without time limit.

8. VTTC(Vacuum Tube Tesla Coil)

As the tubes faded from view, a group of tube enthusiasts built VTTC out of them. Electronic tube itself has high frequency performance and other advantages, so the VTTC effect is very unique. However, there is no denying that the valve itself has the disadvantages of high cost, low life, low efficiency, serious heating and easy damage, caused VTTC has not been widely popular.

9. SSVC(Solid State Valve Coil)

10. OLTC(Off Line Tesla coil)

When we replace the SGTC lighter with a MOSFET or IGBT, and use a diode in reverse parallel on the D and S poles (if IGBT, the C and E poles), then use a solid state circuit to control the switch, with low voltage drive, it becomes OLTC.

Its essence is still LC oscillation, and it is almost the same as SGTC, except that the ignition is replaced by a solid state switch and low voltage drive. Not much else.

As it is driven by low voltage, it cannot generate too much current, so OLTC arc is not as spectacular as SGTC.

Tesla coil calculation formula

1. Formula for calculating circuit length

In the process of making tesla coils, the calculation of circuit length needs to be very accurate, which requires the use of a calculation formula, namely: L=1.7* SQRT (P). In this formula, arc length is L in inches, VA is P in watts and SQRT in square root.

2. Formula for calculating oscillation frequency

The calculation formula of oscillation frequency is F=1/[2*Pi* SQRT (L*C)].

3. Calculation formula of capacitor array

In the production process, the formula for calculating the maximum capacity of tesla coil capacitor array is also the most commonly used, which is C= (10^6) /[6.2832* (E/I) *F]. In the formula, the output voltage of the transformer is E in volt, unit volt, I is the output current of the transformer, the range is milliamperes, the maximum capacity of the capacitor array is C (unit micromethod), and F is the ac frequency (unit Hertz).

4. Ac peak formula

When the capacitor is too large and the ac rises to the peak, namely SQRT (2) *V, when the capacitor voltage is too low to break through the air gap of the lighter, the lighter cannot work and the whole system cannot start.

12 Volt ultra simple tesla coil manufacturing process


1. A FBT,

2. enameled wire: Diameter 0.25mm,length 200m.

3. enameled wire: Diameter 2mm,length 3 meters.

4. A metal ball with a diameter of 12cm

5. diameter of 5 cm, 30 cm long PVC pipe, PVC better, and plexiglass is the most ideal.

6. 2N3055 triode.

7. 240 Ω 5 W, 27 Ω 1W resistance of each one.

8. Some insulation boards a few millimeters thick.

9. 12V battery one.

10. Some non-polar capacitors.

11. A plastic bottle

12. Several meters of enameled wire with a diameter of 1mm.

Tools: electric drill, screwdriver, hand saw, pliers and other tools, common screws, plastic screws, steel ruler and so on.


1. Manufacture of secondary coil

wrapping 0.25mm enameled wire around the pipe. Note: the wires should not cross, as shown below.

secondary coil

2. Production of primary coil

use 2mm enameled wire to wrap it into the shape shown below. It's like a squashed spring. Seven and a half centimeters in diameter.

primary coil

3. Assemble the coil

Attach the end of the wire of the secondary coil to the metal ball. This ball, we call the discharge tip. It forms a capacitor with the ground. Then attaching the ball to one end of the pipe with a glue or hot glue gun. Attach the secondary coil to a plastic sheet. The primary coil is attached to the secondary coil. The other end of the secondary coil is grounded.

4. Combination capacitor

We need some non-polar capacitors, polyester capacitors or ceramic capacitors are recommended. Based on the data of this coil, it is calculated that a capacitor of 21717pF is required. Well, just 0.022 muf (fine tuned depending on the spacing of the igniters).

The voltage tolerance of a capacitor depends on the voltage of the power source, and a voltage box can produce a voltage of one to twenty thousand volts, so the higher the voltage tolerance of a capacitor, the better.

The voltage tolerance of series capacitor is equal to the sum of the voltage tolerance of each capacitor, and the reciprocal of capacity is equal to the sum of the reciprocal of capacity of each capacitor. The capacitance of parallel capacitors is equal to the sum of the capacitance. (When we combine capacitors, try to use the same capacitor.) It is recommended to use 20kv 1000p capacitor series in parallel for 22 times to save material.

5. Make power supply

We can produce high pressure by single - tube self - excited high - voltage baryons. We use a 2N3055 triode.

The black thing is the core of a hyperbaric cable. For the two coils wrapped around the ferrite, use 1mm enameled wire for eight and twenty turns, respectively, from the top to the bottom. The direction of winding must be the same! It is better to install a heat dissipation device for the transistor, because the single tube self-excitation will produce high temperature.If the temperature is too high the transistor will be burned out.

After connecting according to the picture, take the output end of the hyperbaric package, that is, the thickest line and the butt of the hyperbaric package a row of feet to try to pull the arc, find out the longest arc of the feet, the other feet are sealed with insulating paint or hot glue gun and other things. And then, that leads to the two lines on the right.

Single tube self-excitation is not efficient, cutting heat is huge, if conditions can be used ZVS and other circuits.

make power supply

6. Make a lighter

SGTC's principle is to charge the capacitor first till the voltage of the capacitor reaches a certain level, an arc is released from the ignition to form a circuit, and then discharge, and then start the cycle again.

We can use a slightly thicker enameled wire to make a lighter. Generally, the lighter cannot use the tip, it is required to use the smooth surface. Scrape the skin off one end of the two thick enameled wires, bend them into two smooth surfaces, and fix them on the plastic with a hot glue gun, leaving a gap of 6 to 10 mm between them.

There are many ways to make a lighter. Since this one we made is of low power, we don't need to consider the problem of heat dissipation. The ignition of high-power coil is very hot.

7. Final assembly simulation circuit diagram

the total circuit diagram

Due to secondary LC circuit operating frequency can amount to thousands of Hz, high-frequency electric has a kind of skin effect, namely only flows from the conductor surface. The high frequency alternating current, if through the body, only from the surface of the skin, that will not injury to internal organs, so the safety of the coil is still good, the 12 v super simple tesla coil is such a process.

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