Difference between the 2 transformers

So does that mean SMPS won't work since they are operating at about 30KHz(according to SMPS for sale at ebay)?

Plenty of coilers use solid state HV sources inclusing SMPS and flyback designs.

https://en.wikipedia.org/wiki/Neon-sign_transformer


A neon-sign transformer (NST) is a transformer made for the purpose of powering a neon sign. They convert line voltage from the 120-347 V range up to high voltages, usually in the range of 2 to 15 kV. Most of these transformers generate between 30 - 120 mA.

Types[edit]

Older NSTs are simply iron-cored transformers, usually embedded in asphalt to reduce noise. The core has a magnetic shunt which serves to current-limit the output, allowing them to run indefinitely in short-circuit conditions. They can also run indefinitely with no load. Iron cored varieties are quite heavy, for example a 15 kV, 60 mA device may weigh up to 20 kg.

Since the 1990s, manufacturers have been producing switch mode power supplies to power neon signs. These generate the same voltage and current ranges as iron cored transformers, but in much smaller, lighter designs at high frequency (not the common 50–60 Hz). They are gradually replacing iron cored transformers in neon signs.

All NST's are designed to produce a high voltage starting pulse to a tube, then limit the current through the tube when it has started.This is opposite of most line transformers, which will produce full voltage to a load even if overloaded, unless the resistance of windings is too great to allow the excess current or until a winding burns out.

Other uses[edit]

Besides the obvious purpose of powering neon signs, iron cored NST's are often used by hobbyists for:

Tesla coil power supplies – used in small to medium sized tesla coils as the main source of high voltage.
Jacob's Ladder – a climbing arc device often pictured in older horror films.
Charging Capacitors – an NST makes a useful high voltage power supply to charge high voltage capacitors. Although the output of an NST is AC, it can be rectified by the proper diode or bridge rectifier.
.

http://www.personal.psu.edu/sdb229/TCTransformers.html

Somtimes OBITs and NSTs are solid state transformers, they basically work like a miniature tesla coil themselves, they operate at a high frequency to get higher voltage, so they cannot charge capacitors correctly (unless they are rectified and used in a DC coil, but that is a "whole 'nother ball game"). The rule of thumb is if it is really light and small and encased in plastic, it will not work. A regular transformer takes up a lot of space, and is alost always in a metal case, and will have a ground screw attached to it somwhere. If it is one of these seen below, you are good to go.

I know those are dangerous stuff, and yes I do have minimal knowledge about tesla coil designs right now, but do you honestly think that a person knows something without starting from zero?