SGTC build/question thread

[jeffreythe00]

Okay guys I lost my thread progress because my browser crashed. So now I gotta start again.

So anyway while I wait for someone to sell me my dream coil I guess I'll experiment with a SGTC. (And I wonder why I never get projects done!)

Okay so. As you may already know. My experience with these things is 0, Nada, nothing, zilch! However... that doesn't mean I don't have a basic idea how they work .

Anyway I'm going to hopefully use the equipment I have to make a really nice sgtc! My goal would be 1' arcs or close. Though I think the only way that would happen is slow rep rates . Doesn't hurt to try!?

Okay So what I have at my disposal is limited somewhat. I have fly backs but don't really know how to use them for the most part and I have a VERY nice 1kW transmitter tube but I don't have any idea how to use that in a TC. I know if have to make it oscillate but I don't really have a scope and the time to perfect all of that at this time.

So what I will be using is listed below:
Variac
12kv 30ma NST
30kv ??? Pico farad doorknob capacitors or 7-8 MOT caps in series or perhaps homemade caps?
I will be making my own primary/secondary. However I really don't know how many turns it would need. Not having a scope doesn't help I'm sure.
I'm not sure what kind of top load I should use. I understand different sizes are for different kind of coils. So help here would be appreciated.

Anyway I believe that's just about all I would really need parts wise other than the spark gap ofc.

What do you guys think? Is 1' achieve able. Will I just end up getting sucky HF sparks? I know SGTCs are really inefficient. However this will be to explore the science and possibly expand my knowledge with these things.

Suggestions/opinions welcomed!

Thanks for reading!
Jeff

 

[Things]

I'd maybe try putting a few values into here to calculate your secondary and primary values: Javascript Tesla Coil Designer

In general, you can usually just take a stab in the dark with number of turns etc, and tune the primary to match the secondary & topload by changing the tap point.

 

[Fiddy]

hey man,

Im relatively new to tesla coils but not to electrickery, here are a few websites i use for calculating primary and secondary coil data, toroid capacitance and resonant frequency.

First when designing the secondary i choose a wire gauge first, this i a nice page that shows the AWG dimensions and electrical info in inches and mm. This can also be used to work out your primary coil.
Wire Gauge Tables

Secondly now knowing what wire you can work with, enter a helical coil calculator which will tell you, Inductance, length of cable needed, self capacitance and coil height.
Helical Coil Calculator

Once you've got a coil design you like, you can calculate what type of toroid you wanna put on the top.
Toroidal Capacitance Calculator.

Then once you have a ball park design of your Secondary and Toroid, time to find out your resonant frequency.
Resonant Frequency Calculator

Thats my method, i usually have all of them open on 4 tabs and flick between them as i adjust the inductance and capacitance to a Resonant Frequency i desire.

Fiddy.

 

[jeffreythe00]

This is all too much :cryyy:. Can't I just throw it all together and "hope" it works?

 

[Sigurthr]

This is all too much :cryyy:. Can't I just throw it all together and "hope" it works?

Yes actually. But use your flyback and not the nst at first or you will kill it. Keep in mind that if you get 100W of power out of the flyback it is only a fraction of the input power level that sgtcs like.

Once you get a feel for things u can use the nst, but they require a properly designed coil and not a hodgepodge.

Use JavaTc or TeslaMap to input your secondary coil specs and your tank cap specs. Find the resonant frequency of the secondary and the approx turns needed for the primary. Build it (parallel gap, series tank cap, not the other way around) and adjust primary turns for best output. Your spark gap is the most crucial part to set up; if the primary is untuned you can still get good output if your gap is fully quenched and firing well. Space the gap as widely as you can so that no continuous arc forms but it still fires every start up. Quench the gap with air flow strong enough to break the arc. The gap is your switch and when an arc forms and doesn't quench it is the switch getting stuck on. Don't worry about rep rates, just get it firing well.

 

[jeffreythe00]

Hmm. I see. Unfortunately I've never tinkered with fly backs and I'd like to get this project moving before I loose interest in assembly. I've read 2 most in series would work with proper ballasts. I have tons of MOTs. Would this be viable vs a flyback? I understand the spark gap could be an issue with 2 most only outputting 4kv.

Would MOT caps also work as tank caps? I believe I have 7-8 of those as well.

 

[jeffreythe00]

Hmm. I see. Unfortunately I've never tinkered with fly backs and I'd like to get this project moving before I loose interest in assembly. I've read 2 most in series would work with proper ballasts. I have tons of MOTs. Would this be viable vs a flyback? I understand the spark gap could be an issue with 2 most only outputting 4kv.

Would MOT caps also work as tank caps?I have 10 of those as well.

Also my secondary is using 28AWG wire wound around a 3" PVC pipe. The secondary measures 14". I have no idea how many turns there is. My spool of wire kept getting tangled so I stopped counting.

My primary is also finished as well. I've wound 13 turns of ¼ copper tubing. I figure I can always loose a few turns if needed.

My toroid is a very nice dryer hose and is nice and sturdy(not the crinkley kind). I used an 8' length which measures 1.5' across. I figure this is much too massive for my coil which is okay since I plan to buy a proper spun toroid.

 

[Seoul_lasers]

Okay guys I lost my thread progress because my browser crashed. So now I gotta start again.

So anyway while I wait for someone to sell me my dream coil I guess I'll experiment with a SGTC. (And I wonder why I never get projects done!)

Okay so. As you may already know. My experience with these things is 0, Nada, nothing, zilch! However... that doesn't mean I don't have a basic idea how they work .

Anyway I'm going to hopefully use the equipment I have to make a really nice sgtc! My goal would be 1' arcs or close. Though I think the only way that would happen is slow rep rates . Doesn't hurt to try!?

Okay So what I have at my disposal is limited somewhat. I have fly backs but don't really know how to use them for the most part and I have a VERY nice 1kW transmitter tube but I don't have any idea how to use that in a TC. I know if have to make it oscillate but I don't really have a scope and the time to perfect all of that at this time.

So what I will be using is listed below:
Variac
12kv 30ma NST
30kv ??? Pico farad doorknob capacitors or 7-8 MOT caps in series or perhaps homemade caps?
I will be making my own primary/secondary. However I really don't know how many turns it would need. Not having a scope doesn't help I'm sure.
I'm not sure what kind of top load I should use. I understand different sizes are for different kind of coils. So help here would be appreciated.

Anyway I believe that's just about all I would really need parts wise other than the spark gap ofc.

What do you guys think? Is 1' achieve able. Will I just end up getting sucky HF sparks? I know SGTCs are really inefficient. However this will be to explore the science and possibly expand my knowledge with these things.

Suggestions/opinions welcomed!

Thanks for reading!
Jeff

Everything is looking good. 1' (1 foot is very easily achievable)
I'd make one very strong recommendation about the caps. Stay well way from MOT caps as they do explode violently on TC use.
MOT caps are cheap paper and mineral oil and filled and have a nasty habit of turning into pipe bombs spraying you with shards of sharp casing and flaming oil when they fail catastrophically.
You're going to want Cornell dublier pulse discharge caps to make an MMC. (Multi mini Capacitor bank) MMC Caps
http://www.stevehv.4hv.org/DRSSTC2/construction/newMMC.JPG
I recommend these ones. http://www.cde.com/catalogs/942C.pdf
or alternatively .68uF (680nF) 941C20P68K-F.
These will have long life in a TC circuit.

About the primary, You'll want ~12-15x of copper refrigerator tubing which allows you to tune secondary for better output.

I'm assuming the 12Kv 30mA neon is of a non solid state, old style type?

Sparkgaps should be a static type gap/ or air blown. Electrodes should be
either copper tubing

or ZrWo (without Th) cutting rods. 0.5" is best.


Let me know if you want any other info.

 

[Fiddy]

based on what you values you gave,

-------------------------------------
Secondary Coil
-------------------------------------

Wire: 28AWG (0.0126")

Length: 14"

Diameter: 3"

Turns: 1100 - 1130

Length of wire used: 875'

Inductance: 18.165mH

Self Capacitance: 5.57pF

-------------------------------------
Toroid Capacitance:
-------------------------------------

Diameter: 12"

Height: ? guessing 3"

Capacitance: 13.256pF

Total Capacitance
5.57pF + 13.56pF = 19.13pF

Resonant Frequency: 269.98kHz


Is your primary a pancake or helical coil?

 

[Seoul_lasers]

based on what you values you gave,

-------------------------------------
Secondary Coil
-------------------------------------

Wire: 28AWG (0.0126")

Length: 14"

Diameter: 3"

Turns: 1100 - 1130

Length of wire used: 875'

Inductance: 18.165mH

Self Capacitance: 5.57pF

-------------------------------------
Toroid Capacitance:
-------------------------------------

Diameter: 12"

Height: ? guessing 3"

Capacitance: 13.256pF

Total Capacitance
5.57pF + 13.56pF = 19.13pF

Resonant Frequency: 269.98kHz


Is your primary a pancake or helical coil?

I'd recommend a pancake as they're easier to deal with.

 

[Fiddy]

I'd recommend a pancake as they're easier to deal with.

also a lot tastier

you dont need a high coupling for SGTC's do you?

 

[Seoul_lasers]

also a lot tastier

you dont need a high coupling for SGTC's do you?

They tend to be on the very high side for coupling, yes.
Easy to go overboard on the coupling and get racing sparks..

Pancakes.. .delicious. :beer:

 

[jeffreythe00]

Pancake coil. I had a lot of problems with making a comb for a helical coil.

 

[Fiddy]

looking good Jeff!

 

[jeffreythe00]

Were getting there!

Should I add a strike rail or no? Line filters etc? Okay to test this thing in the house away from sensitive electronics?

I plan to laquor that secondary and chop it down to size. Where's the start of the secondary go or should I just laquor over it?

 

[Seoul_lasers]

Were getting there!

Should I add a strike rail or no? Line filters etc? Okay to test this thing in the house away from sensitive electronics?

I plan to laquor that secondary and chop it down to size. Where's the start of the secondary go or should I just laquor over it?

You should be fine without one at this low a power.
First find a flat end cap.. End cap should be almost flush with the end of the windings.
A little space isn't going to hurt anything.

http://www.richardosgood.com/wp-content/uploads/2011/07/2011-06-28_19-42-59_252.jpg