Hey guys. im just here for advice.
Im noooo good with tesla coils as ive tried many kinds but they never work for me so i guess im missing something. all i know is it a bad transformer working on resonance on primary in line with capacitance...

I'm trying to make a spark gap tesla. i built up the circuit to get a comfortable 3kV at the gap at an audable and visible frequency, seeing visible freq cuts off at around 28Hz im guessing im right on the edge as i can juuuuuuust barely sSEE is flicker seems like continious spark almost, ar a 1mm gap. so lets say the primary is 1mm(adjustable gap)28Hz 3KV 4.8uH(tested).
But my secondary is weeeeaaaakkkk.... sparks has increased though to about 9mm(27kv) but weak a.f..... its nothing compared to what ive seen or even bought....
1)why are my secondaries so low....
2)is it because my primary resonance between inductor and cap of f=1/2pi.sqr(LC)=487554Hz does not match my seconday resonance? how do i even calculate that?

im NOT look for huge sparks im looking for normal working so i can get proper 1cm long corona discharge before a spark.... my transformer should be able to suppy enough as it can output about 5kv but somewhere in my multiplyer it gets weaker...

where am i wrong. please advise

 

OK, this goes back a whole lot of years: The spark-gap driven Tesla coils that I have seen did not use the voltage multiplier between the spark gap and the primary. That part will completely filter out any high frequency power and assure that it does not work!!
OR, as I now suspect, the power goes from right to left.
What is missing in that case is the arc constantly re-striking.

The Tesla Coil scheme is a TRANSFORMER and those only work with AC. A DC spark may cause a ringing of a resonant circuit but the result will be difficult to detect.

The successful spark driven Tesla coils that I saw used an ancient FORD vibrating spark coil to drive the spark gap. The capacitor was always glass with aluminum foil on each side. That was because even on the primary side the voltage was quite high.
There were two articles in "Popular Electronics" magazine in that era ,probably 1960 to 1962. "Lil TC" and "Big TC", as I faintly recall .

You will also come across a thing called a "slayer tesla coil" which is about the dumbest creation I have seen in many years. It is a piece of rubbish.

 

You need to determine the resonant frequencies of both the primary and secondary circuits.

 

You need to determine the resonant frequencies of both the primary and secondary circuits.

I have always been puzzled about that aspect of a Tesla coil assembly. Very often the primary (driver) portion is a tuned circuit, but how would one adjust the resonant frequency of that long secondary coil?? IN fact, it is also unclear how the magnetic field engages the top half of the secondary winding. Has anybody actually seen a rational explanation of how that coupling process works?? The magnetic field drawings that I have seen do not seem to fit very well. Are there any experts in magnetic field theory willing and able to explain that to us???

 

Here is how I I understand a spark gap Tesla coil.

A high voltage, low current DC supply charges a capacitor. That capacitor is connected directly through a spark gap to the primary coil. When the spark gap exceeds its firing voltage, it sparks l, completing the circuit of the capacitor and primary coil. This dumps a while lot if energy into to the LC tank circuit, which oscillates at its resonant frequency.

That induces a much higher voltage in the secondary, which is most efficient if it has the same resonant frequency.

Once the energy is all dissipated, the process of charging the capacitor begins again. Thus the spark gap LC circuit forms a relaxation oscillator, which oscillates at a far lower frequency than the resonant frequency, probably tens to hundreds of Hertz.

 

With the spark coil drive it does not wait for anything except the next pulse. The same scheme has been used with a neon sign high voltage transformer.