Pancake Coil

Hello, I was going to try building an old Tesla "Pancake" Coil, and then write an instructable for it. (please don't steal my idea!) Does anyone have any information or building techniques at all that they can give me to help? The Pancake coil is just a Tesla Coil that has a flat secondary, as well as a flat primary. Tesla used it in his early radio and wireless power transmission research. The primary circuit should be pretty much the same as a conventional Tesla Coil. But I am a bit confused as to how to build the secondary. A few questions I have: What wire gauge should I use (I'm pretty sure that Tesla didn't use magnet wire for this)? How do I determine the space in between the turns? (more to come) I realize that most people don't build these kinds of coils anymore, and therefore most people probably won't be able to answer my questions or give me any info; I'd just thought that I would try and see if any one could. It would help me a lot. Thank you.

Picture of Pancake Coil
tesla pancake coil.bmp
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Sessha4 years ago
would fiberglass be a good isulator
JohnW32 Sessha7 months ago

Fiberglass would be a great insulator, almost as good as straight glass. But I would only recommend using it if you have worked with it before or don't have better option.

ElectricUmbrella (author)  Sessha4 years ago
I don't know for sure, but I wouldn't recommend using it.
tarakan19913 years ago
As I can see the theme is 4 years old, but I could not find a better place to ask.
How thick should the papeer be to insulate windings of the secondary?
Bowtie414 years ago
There are lots of places for good info on pancakes(No,not IHOP,lol)

Here is a great site about the Tesla Coil Builders Association:

And another good site for pancake info:

Much More on Google serch.
Good Luck!
ElectricUmbrella (author)  Bowtie414 years ago
Not IHOP? Damn, I was looking forward to spending a long morning there for "research..." ;)

Thanks for the links
waldosan4 years ago
i always wanted to learn how to make a flat "pancake coil" i think i'd have to first make a wire winding jig to make it easy. . . .
ElectricUmbrella (author)  waldosan4 years ago
Agreed, that would definitely be my first step.
A winding jig in this case would consist of three spools - one for the wire, one for the coil, and one for the paper strip going in between the wire. Look at the link that Jiffiycoil posted for info.

EU :)
Where I can get a program or somesing else for pancake coil calculation?
Here is a link to a website with even better calculations.


Not only are there calculators for various aspects of tesla coils; including the pancake coils, resonance, capacitance, and suggested power. They also show you exactly what formula the calculators are using.
I can't vouch for the accuracy. But this website has what appears to be simple equations for calculating inductance, impedance, and capacitance.


Plus some generally good information.
ElectricUmbrella (author)  0123456789107 years ago
Most programs are designed for helical Tesla Coil, I don't think you'll be able to find a program for a pancake type unfortunately.
If I shall wind secondary of my pancake coil, how can I get its resonant frequency?
And what is the best insulator for such devices?
I have read that the wax and rosin is not a good insulator for it on the page http://www.electrotherapymuseum.com/2006/JacksonCoilTesting/index.htm
you can see what was happen with a wax insulated coil.
ElectricUmbrella (author)  0123456789107 years ago
i don't have much experience, but i've heard that 50% beeswax and 50% paraffin wax will work, if you can find it.
mrhed7 years ago
pancake coil design is probally the most efficent one ive wound many of them paper interleaves or using fishing line or just laying the turns side by side using magnet wire and double sided tape to hold the turns down then i vulcanized rubber on to. you dont have to do that using liquid electrical tape will work the same to insulate the coil sometimes it works best to space the turns for maximum performance and power it at lower voltage but higher wattage higher voltages tends to cancel out the effects so a single microwave oven transforemr would serve teh purpose best
jiffycoil7 years ago
This is how you wind the Pancake secondary coil.

ElectricUmbrella (author)  jiffycoil7 years ago
Excellent! Thanks!
How did you seal it in wax?
Take a cake pan and set the coil inside and use it to hold the coil and wax until hardened.
Kiteman7 years ago
"I realize that most people don't build these kinds of coils anymore"

Actually, they are. Try these news links as starters for finding the information you need:

ElectricUmbrella (author)  Kiteman7 years ago
I meant to say "I realize that most coilers don't build this kind of Tesla coil any more." But thanks for the links anyway.