Building My First SGTC! / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Building My First SGTC!

Move Thread

LAN_403

Beazy

Fri Dec 18 2009, 04:32PM

Registered Member #2554 Joined: Fri Dec 18 2009, 03:48PM
Location:
Posts: 3

Hello All,
I am by no means an electrophysisist, but since I was very young, I have been facinated by tesla coils. I have decided to build one finally. I have put aside the $$ and done ALLOT of research. This website has probly answered 1 million of my questions just by using the search tool. But im left wondering one thing:

After days upon days of research, one thing seems to hold true to all new tesla coil builders. . . . It never works on the first try. It takes "TUNING". Since I dont have a background in electronics or high frequency electricity, Im kind of left wondering what exactly does "TUNING" mean. This isnt something I have been able to get a good answer on. When refering to "TUNING" is it all encompasing? For instance, ive seen some people say "Ohh, you need to tune your primary coil" other people have said "Ohh, you need a larger top", "More Caps" etc..... It confuses me, because I cant seem to figure out how/why some people reach these conclusions. How can they tell by looking at a tesla coil, what needs to be "tuned"? How can they do the mathmatical equations in their head just by looking at the pictures.

I have purchased a (24v input) at 20kv and a 5nf MMC at 20kv for making my first MINI SGTC (I dont want to die, so im not going to go larger untill I fully understand every detail and angle of danger on these things) and I have a feeling that I will complete the construction and be left in the cold because I dont understand the intracacies of "tuning" high frequency devices.

If anyone could shed some light on the subject for me, I would be greatful!

Goodchild

Fri Dec 18 2009, 04:54PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Tuning is only relevant with SGTC or DRSSTC as they have a resonant tank cap in the primary. The idea is you have to match the Fo of the primary circuit to the Fo of the secondary circuit. This is done by moving a tap on the primary coil, when you move the tape up or down the primary coil it make the coil bigger or smaller and therefor changes the frequency of the circuit.

Hope this helps, and welcome to the forum!

Beazy

Fri Dec 18 2009, 05:20PM

Registered Member #2554 Joined: Fri Dec 18 2009, 03:48PM
Location:
Posts: 3

Nice, Thanks! That does help.

So I figure ~ If I follow the plans and the math 100%, I should come out on top with a nice working SGTC?

Man I cant wait to get started. I found an awesome mini model on this website that im going to attempt.

I do have one more question. Ive looked through allot of the home made TCs on this site and there was one I noticed that had GREEN and YELLOW and dark Blue streamers, how is that possible? I would 'assume' metal type on the top load. But I could be wrong.

doctor electrons

Fri Dec 18 2009, 05:43PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

If you have not done so already, download wintesla! It is a free program that you can use to determine the frequencies of your coils
by entering information like, number of turns, wire guage, height, and diameter. Pretty cool and very helpful!

Here is a tip on tuning. If you have an oscilloscope and a function generator its a snap! Hooking the function generators positive output to
say the bottom of your secondary coil without the ground side attached to anything. Then using a piece of bare wire attached to your scope probe
(like an antenna) will do the trick. Changing the freq of the generator will show on the scope. When you hit a point of resonance the amplitude of
the waveform on the scope will peak. It will peak at resonance and drop off before and after that point. Just put that probe with the wire
far enough away from the coil that it; itself, does not affect the resonance of the coil. Happy coiling!!

CT2

Fri Dec 18 2009, 05:43PM

Registered Member #180 Joined: Thu Feb 16 2006, 02:12AM
Location: Ontario, Canada
Posts: 187

The colour is either done post production in photoshop or something, or with light filters on the camera (aka TeslaDownUnder) or by burning different materials. Its been awhile since I took chemistry but green would be copper, yellow is sodium (use table salt), the blue is the typical colour which I THINK is nitrogen in the air.

The tuning is basically what Goodchild said, you have primary RLC circuit and a secondary RLC circuit, each circuit will have a natural resonant frequency. You need to adjust the L and the C (inductance/capacitance) of either circuit to make them have the same resonant frequency. It just happens to be easier to change the primary freq. rather then the secondary by simply adding or subtracting caps (changing C), or changing number of primary turns (changing L). Its a delicate balance with MANY variables. Good luck on your coil, make sure to post pics!

Crunchy Frog

Fri Dec 18 2009, 05:50PM

Registered Member #2422 Joined: Tue Oct 06 2009, 02:41AM
Location:
Posts: 85

Have you looked at javatc? I've found it very helpful.

Beazy

Fri Dec 18 2009, 07:26PM

Registered Member #2554 Joined: Fri Dec 18 2009, 03:48PM
Location:
Posts: 3

Nice, thanks guys! I just looked up WinTesla and JavaTC, they both are pretty nice applications. I was using a calculator and paper to figure all those variables out. Its nice to have a consolodated "tesla coil" calculator on hand.

I was thinking about saving money by not purchasing expensive caps, are Beer Bottle caps safe? Ive seen many instructions on how to make them, but I've never had the 'balls' to actually try it. Have any of you had sucess using the beer bottle capacitors?

doctor electrons

Fri Dec 18 2009, 07:45PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

I can understand the money part of it. These things can get a bit expensive! On the other hand, Once you have your coil completed
you want to show it off! Personally i think the bottle caps are a bit dangerous. Sure they work, but when they fail it can get ugly.
Try looking for used or surplus caps. You should be able to get a good deal without burning up your budget. Maybe see what your best
deal is on some caps, and design around that? If you do decide to make the beer bottle caps; MAKE SURE that you locate them in an
area where if they should fail, nothing will be harmed. Use shielding around them. Keep them isolated from the rest of the coil. After all,
they have liquid in them! Blowing those up inside a high voltage device would be very very bad! Give ebay a try, i have gotten caps from
there really cheap. Some cost 50 bucks from suppliers, on ebay i got 20 for 50 bucks! Whatever you do dont give up! It can get a bit
frustrating at times. Remember, learn from your mistakes or dont make them! And above all, like always, safety first!!

Goodchild

Fri Dec 18 2009, 10:57PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

My first SGTC used bottle caps they worked ok but it's best to make a MMC.

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob