TCBA founder, Harry Goldman and the TCBA logo

TCBA - Tesla Coil Builders Association

Devoted to the construction, operation and theoretical analysis of the Tesla coil

TCBA Volume 10 - Issue 1

Page 12 of 18

In conclusion it should be realized that in the .5-4kw power range shunted sign type transformers are hard to beat when they are parallel run for power. Their adantages are:

  1. Line safety (self power limiting)
  2. Arcs in gap systems are much easier to quench allowing the use of multiple static series gaps to achieve max. energy transfer.
  3. Easier on capacitors, electrodes and coils.
  4. Gap criticality reduced as well as cost of construction.

The disadvantages of sign transformers are:

  1. Space required for large arrays.
  2. Cost per unit of power may be high if transformers are purchased new or are expensive used units.
  3. Lots of choke coils and safety gaps are needed to protect each transformer in the system.
  4. Higher overall impedence makes rf kickback into secondaries more likely especially if a rotary gap or poorly balanced condition exists within the sytem.

Above 4kw very large plate or distribution transformers are more practical and offer some unique advantages. They are:

  1. Virtually unlimited power available in a single transformer
  2. Most transformers can be called upon for short bursts of power far exceeding their nameplate ratings.
  3. Space requirements are small.
  4. Some very high power low cost deals can be made. (hamfest “boat anchors”)
  5. In well designed systems sparks are real eye poppers!

Disadvantages involved with non-shunted transformers are many and varied. but must be tolerated to achieve high power in coils. They are:

  1. Weight- 100lbs. is a very light transformer. The largest can exceed 1/2 ton easily.
  2. Power requirements. These babies require 220vac special lines usually at 100 amp rating or more! Special electrician installed lines and boxes according to local codes can often offset a “freebie” pole pig savings.
  3. Arc quenching is difficult and nightmarish.
  4. Special ballasts or Variac inductors needed can be costly
  5. Cost and complexity of gap construction can be prohibitive.
    A professionally constructed tungsten rotary can cost $600
  6. A large separate shop, building or outdoor operation is a must!
  7. High power levels strain capacitors and only the finest need apply here. The cost of construction of suitable capacitors is high due to the increased quality of components required.
  8. Very dangerous for dabblers, dilitantes and the uninformed. Even pros and old hands treat this power level stuff like the dynamite it is. At this level if you get a shock it may not be your first, but it will probably be your last. BE CAREFUL!

No matter what your final choice on transformer system, gap system or power level, a “harmony”, as Tesla would have said, must exist between the elements of your system. This will assure the most efficient and safe operation of any coil system.