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DIY Mini Tesla Coil

A DIY Tesla Coil

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DC Powered with Plasma Output

The aim of this design was to get the highest voltage (or longest arcs) possible from a single self contained unit.

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This coil operates from 12V or 24V SLA batteries. A pair of car ignition coils are used to provide around 20kV for charging the capacitor bank. The ignition coils are driven by a variable frequency square wave from a 555 timing chip and four large transistors (2N3055).


Battery Powered Tesla Coil Input Voltage 12 – 24V DC
Power Consumption 250W Max
Max Arc Length 25cm
Output Voltage(approx) 250kV
Primary Transformer 2 x Car ignition coils in parallel – 20kV
Capacitor MMC 20 kV
Spark Gap 5 x 6mm pipes, Variable
Primary Turns 850
Secondary Turns 850
Secondary Height 40cm
Secondary Width 5cm
Topload 10cm Sphere
Special Features Plasma/Flame discharge terminal Battery powered Fully portable Variable coupling Basic power Management

A pipe from a hole in the top of the sphere and down the inside of the secondary coil is used to supply gas to form a type of plasma electrode.

Flame from coil discharge terminalUsing Butane gas and air, a blue flame can be used as an interesting discharge terminal. The heated CO2emissions provide a low pressure channel to conduct the electricity more easily than air. This produces a large plasma column above the flame. At certain spark gap discharge rates the plasma column can be made to resemble a stable double helix formation. Small quantities of other gasses such as neon or helium can be mixed with the butane to produce slightly different colours and effects. The table below should help you find some of the components needed for this project.

Spring on Tesla Coil thumbnail

Component Max Voltage Source
Ignition Coils ~20kV Click Here
Capacitor Bank 20kV Click Here
HV Diode 30kV Click Here
Power Transistor 400V Click Here
Neon / Helium n/a ST Gas
Control Circuit n/a Click Here

More Plasma Photos

Capacitor BankCapacitor Bank – The capacitor used in this project was made by combining a large number of lower valued capacitors. By connecting smaller capacitors in series the overall voltage they will tolerate is increased. To obtain a higher storage capacity (capacitance) the capacitors can be connected in parallel. This type of capacitor bank is known as an MMC (Multi Mini Capacitors). The next version of this project will use specially designed large pulse discharge capacitors. These capacitors can be more efficient than an MMC, but they can be expensive and hard to find.



Ignition CoilPrimary Transformer – Ignition coils (Induction coils) obtained from a scrap yard are used for this design. The old ignition coils provide a very cheap way of generating a high voltage for charging the capacitor. The voltage increase in an ignition coil is not determined by the turns ratio like in normal transformers. The secondary voltage depends upon the rate of change of the current in the primary coil. Older ignition coils such as ones from a scrap yard may not work as well as new ones. Over time the insulating oil inside the casing becomes less effective and can lead to internal arcing. This can damage the transistors and the control circuit, rendering them useless


Power Transistors on heat sinkControl Circuit – The control circuit is based on a simple oscillator provided by an NE555 timer chip. The square wave pulses are sent to a set of four 2N3055 power transistors mounted on a large heat sink. These transistors can switch a good amount of power quite quickly, but they can be sensitive to voltage spikes caused by feedback in the circuit, or faulty ignition coils. The Ignition coil driver circuit shown below shows how the signal from the 555 chip is pre-amplified, so that the large transistor array can be driven effectively. Using 2N3055 transistors in this way is not ideal, but it is what we had available at the time for the project. Modern IGBT transistors are much more effective and less
prone to failure from voltage spikes.Ignition Coil Driver Circuit Diagram


The output from the ignition coils is rectified (converted to DC using diodes) so that it can charge the capacitor bank C1 shown below.

Rectifier Schematic


Primary CoilCoils – The primary coil is simply made from 2mm enameled copper wire, wound around a plastic stand. There are six turns in total, but the connection is made at about 4.5 turns when tuned. The secondary coil is wound from 0.4mm enameled copper wire around a plastic drainage pipe.



Safety – Attached to the capacitor is a short circuit switch that is activated by a long plastic handle. This is used to make sure the capacitor is fully discharged, and cannot recharge whilst making any manual adjustments. There is also a switch to isolate power from the ignition coils that is activated using a insulating pull cord.

Hole in topload sphereSpecial Features – This project has several extra features compared to a common Tesla Coil. The topload sphere has a small hole to allow gas to be emitted. A 5mm plastic pipe runs down the inside of the secondary coil, and out of the plastic base.

Plasma and Arc Photos

This allows the gas to be piped in, without interfering with the normal operation of the Tesla Coil.


Neon Helium GasFuture Developments – This project is currently being upgraded. The new design aims to achieve a higher power throughput. By using more ignition coils in parallel it should be possible to increase the size of the spark gap, or to fire it more rapidly. New ignition coils will used instead of the second hand ones for improved stability. The new design also incorporates voltage and power monitoring features. It also has a neat metal finish and multiple outputs so that it can be used as a multi purpose portable high voltage power supply

Click here to see the new project

DIY Plasma Globe

DIY Plasma GlobeThere are all sorts of ways to make a plasma globe. This page deals will detail how to make one using a small amount of easily obtainable components. A normal transparent light bulb can be used as a plasma globe simply by connecting it to a high voltage, high frequency source. Most light bulbs contain low pressure Argon gas to prevent the hot filaments from burning. Fortunately this arrangement is also ideal for making contained arcs of plasma. The power supply required for the plasma globe would preferably be a high voltage, high frequency AC type, which could be made from an ignition coil, like the ones used in the Homemade Tesla Coil project. The schematic below shows a driver circuit, for more details see the Ignition Coil Driver page. We also sell a ready made ignition coil driver (shown in the pictures) which also includes extra features.



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Ignition Coil Driver circuit diagram


Assembling the Plasma Globe

Parts needed to construct a plasma globeThe following parts are used for the video demo of this project;

First the spring must be attached to the bottom of the light bulb; this can be done using a bit of tape. The spring is used to ensure a connection between the bottom of the bulb and the high voltage output within the end of the ignition coil. Next, the bulb and spring are fixed tot he end of the ignition coil with some more tape.

The ignition coil is connected by two wires to the PWM circuit at the L+ and L- terminals, and the power supply is connected to GND and V+. Also connected to V+ and GND is the electrolytic capacitor. This is connected close to the circuit board and is used to keep the DC input stable. It is important to note that the orientation of the capacitor must be correct. To know which way around it should go look for the longer leg (which indicates the positive) there is also often a stripe on the side of the capacitor to indicate the negative side.

Finger of PlasmaThe settings on the PWM circuit will need to be adjusted so that good streamers become visable in the coil. Always begin with the duty setting at zero then slowly turn it up to around 50%. The frequency setting is then adjusted while observing the apperance of the plasma inside the lightbulb. At some frequencies no plasma will be seen, while when at the right frequency there should be lots of streamers dancing around inside the bulb. The frequency needs to be fairly high and the buzzing sound from the coil will become so high its is amost inaudiable.

When operating the circuit great care must be taken as the ignition coil could output around 20-30kv when using around 15V, 5A from the power supply.It should not be touched as it will give a nasty shock.


DIY HHO Hydrogen Production a Water Fuel Cell

DIY HHO Hydrogen Production a Water Fuel Cell

DANGER: This project involves creating a mixture of Hydrogen and Oxygen which is a highly EXPLOSIVE GAS. When contained in a confined space, detonation of the gas would be highly dangerous and could cause serious injury.

How it works
Water is a compound made from the two elements of Hydrogen and Oxygen. It has the chemical symbol H2O which indicates that each molecule is a combination of one Oxygen atom and two Hydrogen atoms.

All atoms can form ‘ions’. These are just the same atom except with a little extra charge. Atoms can become ionized when in the presence an electric field. You can see extreme examples of this in the DIY Tesla Coil project. Hydrogen forms positive ions, and oxygen forms negative ions. We use this to our advantage by using an electric field to pull the water molecules apart.

By placing two electrodes (metal plates) into water we can create an electric field between them by connecting them to the terminals of a battery or power supply. The positive electrode is known as the anode, while the negative one is the cathode. Pure water actually does not conduct electricity so it is not suitable to be used without adding something to the water. Tap water already contains many dissolved compounds which allow the water to conduct. The ions formed in the water will be attracted to the electrode of opposite polarity, i.e. the positive hydrogen ions will move towards the cathode, while the negative oxygen ions move to the anode. Once the ions reach the surface of the electrodes the charges will be neutralised by adding or removing electrons. The gas is then fee to bubble up out of the remaining water to be collected.

The electrodes are typically made from metal or graphite (carbon) so that they can pass electricity into the water. It is important that the chosen material does not react readily with oxygen or one of the dissolved compounds otherwise reactions will occur at the surface of the cathode (negative electrode) and the water will become polluted with the products of the reactions. You will see an example of this below when copper electrodes are used. This also means that no or very little oxygen gas is released as it gets combined with the metal electrode and remains in the container.

Copper ElectrodesThe Project

This is a simple project that is used to create Hydrogen and Oxygen gas by electrolysis of water. The aim was to get good gas production rates without using extra chemicals or eroding the electrodes.

The first electrodes tried were ones left over from a different project. They were made from Copper coated Carbon rods which are not ideal due to copper being able to react with the water. The idea was that the copper would eventually all react away and there would be just Carbon left which would not pollute the water.

The copper seemed to take too long to react away and it was decided that this would not be useful at all. Below you can see the result of using copper electrode for electrolysis. The blue sludge floating on the surface of the water is some reactant of the copper and tap water.

Blue Copper

Many people use electrodes made from stainless steel kitchen ware or switch plates because the stainless steel does not react as easily. The problem is that the grade of the steel often found in such items is not great and you will be left with a brown sludge after a few minuets of operation. They are also quite thin, usually less than 1mm, which means that the do not last a very long time before being totally eroded away. The erosion of the electrodes happens much more quickly when high currents or solutes (often called catalysts) are used.

The volume of gas produced is proportional to the charge passing through the water (current) and therefore high current means more gas. To do this the spacing of the electrodes must be as close as possible while still having enough room for the gas to bubble out freely.

The metal chosen for the plates was special high grade stainless steel to reduce corrosion. Such metal is not as conductive as others like copper for instance, so these plates were made from thick sheets of 2mm to counter this potential limiting factor. Very high quality metal was used which meant it was too hard to cut with common DIY tools so these plates were cut using a high pressure water jet. 

 INFORMATION: Even the highest grade stainless steel will have some reaction with water and can produce toxic chemicals. Avoid touching the water after use.

HHO Electrodes

The plates are layered on top of each other with nylon washers between used as spacing. They are placed in alternating positions so that the plates would be +-+-+-. Stainless steel fixings were then used to fit it all together. It is important that it is put together well otherwise sparks could occur in the gas production area resulting in an explosion.

ElectrodesA total of 16 plates were used in with 1mm spacing between each of them. The large combined surface area and thickness of the plates and bolts meant that this could carry very large currents without significant resistive heating in the metal. The total capacitance of the electrodes was 1nF when measured in air which indicates a large close surface area for gas production. This set of electrodes would draw about 25A from ordinary tap water. To collect the gas, the electrodes need to be placed in some sort of container. The container used was just something from a supermarket and was originally intended for storing something like tea!

This video shows the result of applying 12V to the electrodes when submerged in ordinary tap water. No ‘catalysts’ have been added to the water at all, this is just tap water!

It is drawing about 25A. Power to the cell is controlled using a pulse width modulation circuit.

The container was made from metal so it was important to place the electrodes on a plastic base to prevent any short circuits. This image shows how two banana sockets were installed either side of some copper and brass fittings used to extract the gas. The power and pipe fittings were screwed tightly and sealed with silicon sealant so that the closed container would be air tight.

The gas produced is a highly explosive mixture of Hydrogen and Oxygen and should be treated with extreme caution. A large volume of gas exists inside the container which if ignited would explode and destroy the container. To avoid detonating the gas, the pipe from the container is fed into the base of another container which is half filled with water. This allows the gas to bubble trough the water to then be collected via another pipe which is used as the gas output. Now if any ignition occurs at the output, the flames can’t get back past the bubbler device and into the large gas volume in the electrolysis cell. This is an absolutely essential safety device and should not be skipped.

Now it is just deciding what to do with the gas! A good way to see the how explosive the gas mixture is to bubble the gas through another container of water such as a mug and ignite the bubbles as they reach the surface. Each bubble will explode very loudly and probably blow out the lighter.

A similar project which uses the explosive properties of the gas is the Hydrogen Cannon experiment.

 You should be aware that detonating this HHO gas mixture is VERY VERY loud.

Spark coil uses

You probably wouldn’t realize but you use spark coils all the time whether you’re cooking a meal or driving a car, spark coils are everywhere and their applications are countless. I will list a few.

If you’d like to try these things for yourself then be warned, spark coils are high voltage and should only be used by those who know what they’re doing, if you do know what you’re doing then you can buy spark coils here on the RMCybernetics shop.



An electric arc or arc discharge is an electrical breakdown of a gas that produces an ongoing plasma discharge, resulting from a current through normally non-conductive media such as air.


An electrical discharge results from the creation of a conducting path between    two points of different electrical potential in the medium in which the points are immersed. If the supply of electrical charge is continuous, the discharge is permanent, but otherwise it is temporary, and serves to equalize the potentials. Usually, the medium is a gas, often the atmosphere, and the potential difference is a large one, from a few hundred volts to millions of volts. If the two points are separated by a vacuum, there can be no discharge.

An spark coil can be used to make arcs by putting a high voltage through it and putting it close to ground.



DIY Plasma globes :

untitled-3A glass globe containing a low density gas and a central electrode that creates lightning-like streams of light. These fronds of plasma make their way from the centre of the globe to the edge, in a bid to reach earth. Creating an enhanced path to earth by touching the globe increases the strength of the discharge, which is why the arcs are attracted to your hand if you touch the globe.




Jacobs ladder:

jacobs-ladderThe Jacob’s ladder is a high voltage climbing arc. An electric spark jumps between two parallel wires. The spjacobs-ladder-2ark then “climbs” up the ladder. The transformer at the bottom creates a potential difference between the wires. The electrons repel each other, so they jump from one wire to try and get as far apart as possible. The spark heats up the surrounding air and hot air rises, so the spark rises with it. When the spark gets to the top of the wires, it dies and a new one starts at the bottom.




DIY Fly swatter/Bug trap:

diy-fly-swatter-bug-trapThis can be made using a high current through a set of parallel wires and set of parallel grounded wires running horizontally/vertically (whichever way the high current wires aren’t).

The high voltage supplied by the coil, at least 2,000 V, is applied across the two wire-mesh grids. These grids are separated by a tiny gap, about the size of a typical insect (a couple of millimetres). The light inside the wire-mesh network lures the insects to the device (many insects see ultraviolet light better than visible light, and are more attracted to it, because the flower patterns that attract insects are revealed in ultraviolet light). As the bug flies toward the light, it penetrates the space between the wire-mesh grids and completes the electric circuit. High-v­oltage electric current flows through the insect and vaporizes it.



taserA Taser or Thomas A. Swift’s Electric Rifle is a device that fires electrified probes used to temporarily incapacitate someone.

A Taser works by delivering high voltage — but low amperage — to the human body. A Taser delivers a powerful but temporary shock rather than a sustained and deadly charge.


Electric fence

electric-fenceThe most common use for an electric fence is to contain animals in a certain space by deterring them (often using mild shocks) from crossing a boundary. While possible to be run from an spark coil in a DIY situation it is highly recommended NOT to as it can be very dangerous.






An spark coil (also called an ignition coil) is an induction coil in an automobile’s ignition system which transforms the battery’s low voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel therefore ignition is its primary function.

Feel free to list a few ideas you think I should have mentioned in the comments section.