THE NATIONAL INSTITUTE OF

ENGINEERING.
MYSURU-570008

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

ENGINEERING
MINI PROJECT [EC0201]
VI Semester
Synopsis On

TESLA COIL
Under the guidance of
Mr. PUNEETH S
Assistant Professor, Dept. of ECE.

Submitted By:
S SUBHASH - 4NI15EC091
NAVEEN S - 4NI15EC068
 TESLA COIL 2017-18

CONTENTS
• INTRODUCTION

• BLOCK DIAGRAM

• CIRCUIT DIAGRAM EXPLAINATION

• APPLICATIONS

• ADVANTAGES

• DISADVANTAGES

PROJECT CO-ORDINATOR GUIDE

MR. C. ANJANAPPA Mr. PUNEETH S

(Assistant Professor, Dept. of ECE.) (Assistant Professor, Dept. of ECE.)

Dept. of ECE , NIE , Mysuru page no. 1

 TESLA COIL 2017-18

TESLA COIL

INTRODUCTION

A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in

1891.   It is used to produce high-voltage, low-current, high   frequency   alternating-

current electricity.Tesla experimented with a number of different configurations consisting of two, or
sometimes three, coupled resonant electric circuits.

Tesla used these circuits to conduct innovative experiments in

electrical   lighting,   phosphorescence,   X-ray generation,   high frequency   alternating current
phenomena,   electrotherapy, and the   transmission of electrical energy without wires. Tesla coil
circuits were used commercially in spark gap radio transmitters telegraphy until the 1920s, and in
medical equipment electrotherapy and violet ray devices. Today their main use is for entertainment
and educational displays, although small coils are still used today as leak detectors for high vacuum
systems.

BLOCK DIAGRAM
The Tesla coil is well-known for producing extremely high voltages. In this section, we’ll
explain how the Tesla coil can reach voltages over a thousand volts using coupled resonant circuits.
We’ll build up from the fundamentals, to give you a thorough explanation of what’s going on . Here
fig.1 shows the basic block diagram representation of a Tesla coil.

Fig.1 Tesla Coil Block Representation

Dept. of ECE , NIE , Mysuru page no. 2

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CIRCUIT DIAGRAM
Tesla coil is a radio frequency oscillator that drives an air-core double-tuned resonant
transformer to produce high voltages at low currents.Tesla's original circuits as well as most modern
coils use a simple spark gap to excite oscillations in the tuned transformer. More sophisticated
designs use transistor or thyristor switches oscillators to drive the resonant transformer. Here fig.1
Shows the circuit diagram representation of the Tesla coil that will be used in this experiment.

Fig.2 Tesla Coil Circuit diagram

OPERATION

A Tesla Coil is an air-cored resonant transformer. It has some similarities with a standard

transformer but the mode of operation is somewhat different. A standard transformer uses tight
coupling between its primary and secondary windings and the voltage transformation ratio is due to
turns ratio alone. In contrast, a Tesla Coil uses a relatively loose coupling between primary and
secondary, and the majority of the voltage gain is due to resonance rather than the turns ratio. A
normal transformer uses an iron core in order to operate at low frequencies, whereas the Tesla Coil is
air-cored to operate efficiently at much higher frequencies.

Dept. of ECE , NIE , Mysuru page no. 3

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The operation of the Tesla Coil is as follows:-

1. The spark gap initially appears as an open-circuit. Current from the HV power supply flows through
a ballast inductor and charges the primary tank capacitor to a high voltage. The voltage across the
capacitor increases steadily with time as more charge is being stored across its dielectric.

2. Eventually the capacitor voltage becomes so high that the air in the spark gap is unable to hold-off
the high electric field and breakdown occurs. The resistance of the air in the spark gap drops
dramatically and the spark gap becomes a good conductor. The tank capacitor is now connected
across the primary winding through the spark gap. This forms a parallel resonant circuit and the
capacitor discharges its energy into the primary winding in the form of a damped high frequency
oscillation. The natural resonant frequency of this circuit is determined by the values of the primary
capacitor and primary winding, and is usually in the low hundreds of killo hertz .During the damped
primary oscillation energy passes back and forth between the primary capacitor and the primary
inductor. Energy is stored alternately as voltage across the capacitor or current through the inductor.
Some of the energy from the capacitor also produces considerable heat and light in the spark gap.
Energy dissipated in the spark gap is energy which is lost from the primary tank circuit, and it is this
energy loss which causes the primary oscillation to decay relatively quickly with time.

3. The close proximity of the primary and secondary windings causes magnetic coupling between them.
The high amplitude oscillating current flowing in the primary causes a similar oscillating current to
be induced in the nearby secondary coil.

4. The self capacitance of the secondary winding and the capacitance formed between the Toroid and
ground result in another parallel resonant circuit being made with the secondary inductance. Its
natural resonant frequency is determined by the values of the secondary inductance and its stray
capacitances. The resonant frequency of the primary circuit is deliberately chosen to be the same as
the resonant frequency of the secondary circuit so that the secondary is excited by the oscillating
magnetic field of the primary.

5. Energy is gradually transferred from the primary resonant circuit to the secondary resonant circuit.
Over several cycles the amplitude of the primary oscillation decreases and the amplitude of the
secondary oscillation increases. The decay of the primary oscillation is called "Primary Ringdown"

Dept. of ECE , NIE , Mysuru page no. 4

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and the start of the secondary oscillation is called "Secondary Ringup". When the secondary voltage
becomes high enough, the Toroid is unable to prevent breakout, and sparks are formed as the
surrounding air breaks down.

6. Eventually all of the energy has been transferred to the secondary system and none is left in the
primary circuit. This point is known as the "First primary notch" because the amplitude of the
primary oscillation has fallen to zero. It is the first notch because the energy transfer process usually
does not stop here.

7. This energy transfer process can continue for several hundred microseconds. Energy sloshes between
the primary and secondary resonant circuits resulting in their amplitudes increasing and decreasing
with time. At the instants when all of the energy is in the secondary circuit, there is no energy in the
primary system and a "Primary notch" occurs. When all of the energy is in the primary circuit, there
is no energy in the secondary and a "Secondary notch" occurs.

8. Each time energy is transferred from one resonant circuit to the other, some energy is lost in either
the primary spark gap, RF radiation or due to the formation of sparks from the secondary. Therefore
both the primary and secondary amplitudes would eventually decay to zero.

9. After several transfers of energy between primary and secondary, the energy in the primary will
become sufficiently low that the spark gap will cool. It will now stop conducting at a primary notch
when the current is minimal. At this point any remaining energy is trapped in the secondary system,
because the primary resonant circuit is effectively "broken" by the spark gap going open-circuit.

10. The energy left in the secondary circuit results in a damped oscillation which decays exponentially
due to resistive losses and the energy dissipated in the secondary sparks.Secondary Ringdown after
spark gap stops conducting.Since the spark gap is now open-circuit the tank capacitor begins to
charge again from the HV supply, and the whole process repeats again.

It should be noted that this repeating process is an important mechanism for the generation of long sparks.
This is because successive sparks build on the hot ionised channels formed by previous sparks. This allows
sparks to grow in length over several firings of the system.

Dept. of ECE , NIE , Mysuru page no. 5

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APPLICATIONS

• Wirelessly Transmit Electricity

• Shoot Lightning Bolts
• Electrify The Body
• Make Wicked Lightning Music
• Make Electron Winds

ADVANTAGES

• High Voltage Production

• Wireless Electricity Transmission

DISADVANTAGES

• Ozone Poisoning
• Radio Frequency Interface
• Secondary Coil Shocks

PROJECT CO-ORDINATOR GUIDE

MR. C. ANJANAPPA Mr. PUNEETH S

(Assistant Professor, Dept. of ECE.) (Assistant Professor, Dept. of ECE.)

Dept. of ECE , NIE , Mysuru page no. 6