My first Tesla Coil - Page 1
Forum section: electronics / beginners

author: rodrigopires
author_rank: Regular Contributor
timestamp: June 04, 2015, 07:24:56 pm
content: Hi, i´m doing my first tesla coil and i want to use MOT as a power supply, mine have about 2KV AC output, do i need do have a higher voltage? My secondary is about 2" by 8". What is the best primary for this type of small coils? Conical? Cylindrical? Flat? And the number of turns? And how about the capacitor bank, i used a formula i found online to calculate the ideal capacitance depending on the power supply, but MOT's have a bit of a high current ( about 2A) on the secondary and the equation ended up giving me 2.6uF, which i think is alot! And can i use a single capacitor instead of a bank? What are the differences?My plan is to make a small tesla coil as my first just to see how it goes, but my goal is to make a musical tesla coil. But i think that for that i cant use MOT's, because with MOT's i have to use a rotary spark gap and musical tesla coils have a simple spark gap and higher voltages and lower current. Right?In the attachements is my secondary coil and my cylindrical 5 turn primary.Thanks!

author: klr5205
author_rank: Regular Contributor
timestamp: June 04, 2015, 08:02:22 pm
content: 2kV might be on the low side for a spark gap tesla coil, but you might get it to work with a fairly small gap. Just to get something working, a cylindrical coil should be fine. There is a metric ton of reading that can be done on the optimal shape (and inductance) of your primary coil.One thing to note is that one of the traditional choices for a small to medium sized SGTC is a neon sign transformer. These can be found at voltages from around 5kV up to 12kV and are inherently current limited to under 30mA or so. The old style without the GFCI circuits are best. You'll have to defeat any such features if you ever get a newer one.As far as making a musical tesla coil... I'm not familiar how they do it with the spark gap topology but I could almost guarantee you it'd be easier to do with a SSTC...

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 04, 2015, 10:11:30 pm
content: Yes.... MOTs are a rather dangerous choice for one's first SGTC. Here's my MOT-DC coil in action, using a rather inefficient blown 2-element gap (not rotary):No, you aren't going to be playing music through a Tesla coil of this type! Spark gaps make a lot of noise on their own!I'd suggest starting out with a Solid State Tesla coil, which can be scaled down to low enough power levels to make it safe to work with on the workbench. And they are much easier to audio modulate. You can probably use your existing secondary and maybe your primary as well. Search for "PLL SSTC" and you'll find a lot of examples. For an even more basic, very low powered type of SSTC, search for "Slayer exciter". Here's the PLL Class E SSTC that I'm currently working on:Or if you're heart is set on making a SGTC, I'd suggest using a neon sign transformer (NST) as noted above. They are a lot safer than the MOTs due to the current-limiting feature and you can sometimes get them cheaply from used signs, check your local sign shop.Or you could consider using a flyback transformer from an old CRT TV or monitor as the primary source. A simple ZVS driver for the flyback transformer, the right capacitors and spark gap construction and you have a hybrid SS-SG TC. Here's mine running on 24 VDC from a couple of batteries:The multiple capacitor bank is commonly used to build up the capacitance and voltage rating needed for your primary tank.

author: rodrigopires
author_rank: Regular Contributor
timestamp: June 08, 2015, 01:16:49 pm
content: Thanks for the help, it was really great having this support on my project! I had already watched this videos on youtube and found them really great! I will try to get a NST to make thing more easier. Meanwhile i will be experimenting with the MOT's.