A Breakdown of Tesla Coils


A Tesla coil has two separate parts, the primary and secondary circuits, each of these consists of a capacitor and an inductor, so they each become resonant circuits when voltage is applied. The secret behind a good Tesla coil is making both resonant at the samTesla Coil Componentse frequency, allowing them to interact with one another.

While I knew the basic components that make up a Tesla Coil and how they all fit together, I was still having trouble really understanding each part, which would enable me to deconstruct the coil and put it together in a new design for my character, while ensuring that the basic science behind it remained in tact.

For my design, I am imagining a scenario much like that of the Fallout universe – an alternate timeline similar but slightly different to reality, in this case the change would be that Nikola Tesla became the big name in electricity instead of Thomas Edison, and all future electrical innovation was based on his work. Because my character does not live in a history that we know, I don’t have to be too faithful to the original in my designs, as this would be a time that has developed Tesla’s original designs further than we have today, modifying and improving them accordingly.

When I was starting to lose hope about ever understanding the physics jargon about transformers and AC current, I found a website that explains the basic theory behind Tesla Coils perfectly;


There was already a question on the site asking how Tesla Coils work, and the explanation is so simple, it finally makes perfect sense

The picture you should have in your head is a long bathtub, open to the ocean on one end.  The machinery of the Tesla coil is like some dude in the bathtub sliding back and forth, splashing water (electrons) out of the closed end, while the tub is refilled from the ocean (ground). The electricity in the primary coil is what’s doing the pushing, and the electricity in the secondary coil is what’s being pushed

In a very basic way, that explains the function of the main visible components – the secondary coil is a bathtub full of electricity, and for it to escape as sparks from the top of the coil it must be pushed back and forward by the alternating current of the primary coil until it overflows.Coil Circuit

It goes on the explain why the coil is needed, and what the other parts are for, using a new metaphor. For example, plucking a guitar string once a second results in a frequency of 1hz, but the guitar string vibrates at its own frequency. Similarly, the power coming from the wall to power the Tesla Coil has a relatively low-frequency (60hz), while the secondary coil needs a much higher frequency to ‘slosh’ the electricity out of it, meaning that it will move back and forward thousands of times before the wall current turns over once. To change this frequency the coil much be ‘plucked’ like the guitar string.

The only job that the slow part of the circuit has is to charge the capacitor (pull back the string).  When the spark gap sparks (pluck!) the fast part of the circuit takes over, and the slow part is essentially ignored until all the energy is exhausted by exciting the secondary coil (string vibrates and slows)

Slow Circuit

Basically there are 2 parts to the circuit – the slow part (mains, transformer and capacitor), and the fast part (spark gap, coils, torus)

Fast Circuit

The slow circuit works by the transformer forcing charge to build up in the capacitor (like holding back a string), until the charge in the capacitor reached a high enough voltage to activate the spark gap (plucking the string)

Once the spark gap opens, the electricity can flow out of the capacitor through the primary coil, flowing up and down the primary coil and creating a high enough voltage that electricity flies out of the top.

The parts I need to include would be;

  1. Power Source
  2. Transformer
  3. Capacitor
  4. Spark Gap
  5. Primary Coil
  6. Secondary Coil
  7. Discharge Terminal

The discharge terminal and main parts are often aluminium (used because it controls and directs the current away from the user), with copper used for the coils as it’s such a good conductor and allows the electricity to easily pass through

Scrapped design for a Portal Gun, cool moving parts

Scrapped design for a Portal Gun, cool moving parts

This description perfectly simplifies things for me, and once I learned about the parts in that way, and exactly what I could get a way with changing, I began to get ideas for my character design.

I like the idea of stretching out the spark gap so that it is visible as a working mechanism inside the gun, much like in early designs for the portal gun. This makes the character far more interesting visually, while adding a cool sci-fi element.

Extending the spark gap to be the main focal point means I can hide the boring parts like the transformer and capacitor in the covered over parts connected to his arm. Much like with the Tesla gun, the secondary coil sticks out of the gun, while the primary coil can be enlarged an wrapped around the barrel, which is a really cool visualtesla gun

  • How Tesla Coils Work. 2013. How Tesla Coils Work. [ONLINE] Available at: http://www.hvtesla.com/. [Accessed 02 November 2013].


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s