Newspaper and magazine articles related to Nikola Tesla

Nikola Tesla Articles

Newspaper and magazine articles related to Nikola Tesla

Misconceptions of the Violet Ray

January, 2006
Page number(s):

Tesla Coil Roots

This Vintage Master Violet Ray built by Master Electric Co. (Chicago) was recently sold on E-Bay.

It’s long been overdue to clear up some misconceptions about Violet Ray devices! Whether you know them as High Frequency Violet Rays, Violet Wands, or Leak Detectors, these devices have been a source of amusement, controversy, and confusion over the years.

The basic Violet Ray machine is a portable form of Tesla Coil. It is based on some of the early coils Tesla built in his Houston Street Laboratory. These coils would consume from 5-20 watts from a 110V power source and produce an impressive shower of 4” sparks. Tesla’s coil devices would easily supply more than enough power for the average Crookes tube, yielding penetrating Röentgen Rays. It was one of the many functions envisioned by Tesla for the practical use of these devices.

By 1895, Frederick Finch Strong adapted the Tesla Coil and placed vacuum electrodes on it, thus inventing the “Violet Ray”. Although Tesla invented the power source and helped develop the field of high frequency electrotherapeutics, he was too busy to focus on the commercialization of his coil at that time. Tesla indirectly commented on his lack of effort over twenty years later in 1919:

... From the very beginning I felt the necessity of producing efficient apparatus to meet a rapidly growing demand and during the eight years succeeding my original announcements I developed not less than fifty types of these transformers or electrical oscillators, each complete in every detail and refined to such a degree that I could not materially improve any one of them today.

Had I been guided by practical considerations I might have built up an immense and profitable business, incidentally rendering important services to the world. But the force of circumstances and the ever enlarging vista of greater achievements turned my efforts in other directions. And so it comes that instruments will shortly be placed on the market which, oddly enough, were perfected twenty years ago!

Master Violet Ray, from T. Mueller U.S. Patent 1,524,876 - From left to right: Vacuum Electrode, Resonator Coil, Magnet Coil/Condenser, Interrupter, Line Cord

Violet Ray Applications

These devices started off legitimately as medical devices for treating various skin conditions and for the minor relief of pain. They were made originally for physicians to take to their patients’ homes where portability and convenience were a must. An added bonus for these early machines is the unique ability to operate on both alternating and direct currents. Even if a patient’s home did not have electricity, these small devices could run from portable battery banks.

Electrotherapy was an accepted part of medical practice. Violet ray devices in a doctors office tended to be much more powerful and larger than those developed for home use.

Prior to this, most high frequency devices were large and cumbersome, and available electricity was rare. It also may be of interest to note that in the early days if people were lucky enough to have electricity in their homes, the extent to which this existed was most often a single lamp socket hanging from the ceiling of the main room in the house. Wall switches and outlets were still in the distant future! This is why so many Violet Ray manuals mention things such as “conveniently plugs into any lamp socket”. Evidently, at the time, a lamp socket was the only form of outlet readily available!

Early portable apparatus manufacturers included Remco, Frank S Betz, Browne, Victor, Fischer, Aloe, Wappler, Etc. Most of the early devices were stored in lined oak boxes and contained coils that produced sparks up to 3” or more. Some units were even sold with special X-Ray tubes for doing mild treatments at people’s homes.

Quack Medicine?

Soon America became the world of patent medicine and quackery, and many manufacturers making the devices began to advertise them as cure-alls. Violet Ray manufacturing was a major US industry, from 1900 until the 1930s with over three dozen manufacturers making these units. Some manufacturers made up to a dozen models, and production ran into the tens of thousands... even hundreds of thousands of violet rays for some companies!

Eventually the cure-all claims were put to trial and most of the devices were banned by the FDA for illegitimate claims. Cenco and Electro-Technic Products began marketing the devices as high frequency leak detectors for neon sign and related industries. They are still manufactured for this today. Several other companies, such as Fromm International, Siluoet-Tone, Holo-Electron, and Tefra make the devices for beauticians or aesthetician use.

In recent decades many people began distributing devices from the above companies as adult novelties or alternative medical devices. It should be noted that today in the US, the only legitimate manufacturers of these devices are Electro-Technic Products (Leak Detectors) and Fromm International (Aesthetician Products). Electro-Technic Products manufactures modern versions of the Cesco, Energex, Challenger, and Cenco models of Violet Rays, and Fromm makes the Master Electric M66, Master Appliance, and Gibbs Violet Ray models. Neither manufacturer makes or endorses the use of the machines as “Violet Rays”, or “Violet Wands”.

In Europe, there are still several manufacturers of “Violet Rays”. Holo Electron in France, and Tefra in Germany. Many of the hard to find electrodes are still sold by these companies.

Inner Core Construction

Cross-section of a Master (Fromm) Resonator Coil illustrating the core and its insulation.

One of the common misconceptions about Violet Rays is the actual disruptive discharge coil in the top of the unit, the coil that makes connection with the glass electrodes. Many internet resources make mention of “wax cores” used in these coils. One company even boasts the use of ceramic cores(!) This information is false.

Violet Ray resonator coils are wound on wooden or plastic cores; they contain multiple layers of wire insulated by paper which is impregnated with insulating material. It is the overheating of this insulating material between layers that causes these coils to fail. Below is a cross section of some Resonator Coils.

Capacitor Construction

Another important note and misconception is that if modern capacitors replace the original tin/waxed paper varieties the overheating of the coils will be prevented. In fact, the opposite occurs. Because the coils are wound with copper, this metal dissipates the heat quickly. (In the case of secondary coils, this is why the wax melts from the interleaves). In older coils with tin foil condensers, the heat was actually transferred to the condenser, which is why they often failed before the coils when operated for extended periods. This is to a large advantage, because replacing a condenser is much less intensive than rewinding a complex disruptive discharge coil.

Cross-section of a Cesco (ETP) Resonator Coil illustrating the core and its insulation.

Today most condensers (“capacitors” by today’s terminology) are made smaller and with aluminum plates. Aluminum radiates heat at nearly the same degree as copper, making the heating distributed between both the coil and the condenser - meaning that both have a potential for failing. With modern dielectrics becoming smaller and smaller, the amount of metal required in the condenser is less, and the smaller surface area of metal means that less heat is taken away from the coil, which now has an even greater chance of failing. Large, bulky, unattractive waxed paper and tin foil condensers are not as bad as they look! In the case of rare Pancake Coils for larger apparatus, saving a coil and losing a condenser is nothing to cry about.

You can clearly see the different layers of wire, and the waxed paper used for insulation. The secondary coil is close wound layers with wire .006” in diameter, while the primary is a single layer wound with .012” diameter wire. Some manufacturers used two wires wound side-by-side for the primary winding to increase the coupling of the coils.

Heat Reduction Techniques

Today it’s possible for coils to be impregnated with high temperature epoxy rather than wax, making a coil that will withstand extended use. Unfortunately, the other components of the Violet Ray (such as the condenser or magnet coil) also tend to overheat when operated for more than 10 minutes - defeating the purpose of a heavy-duty coil.

Whether or not you believe in the authenticity of the treatments, most “treatments” lasted no longer than 10 minutes, and if the machine is allowed a 20-30 minute period of “cooling off” between treatments it will last a lifetime. Violet Ray machines are often more expensive to repair than they are worth, so it’s best just to take good care of them and they will last indefinitely.

High Frequency High Voltage Generation

Another misconception is that Violet Rays contain transformers and spark gaps. They actually contain a “self-induction coil” and “interrupter”. The self-induction “magnet coil” is really a single layer of wire that magnetizes an iron core. Whenever the core is magnetized, the bottom contact of the interrupter (which is attached to a steel armature) is attracted to the core of the coil, thus breaking the contact of the interruption. At this point the collapsing magnetism in the core of the coil induces a high voltage back-emf in its winding of around 1-2 kV.

This high voltage is used to charge a condenser and discharge it across the disruptive discharge “resonator coil”.

The combination of inductance and capacity form a high frequency resonant circuit, and it is through resonance that a small coil operating from a 110V source can yield an output of over 50,000V with very little wire.

Discharge Electrodes

Finally, the actual glass vacuum electrodes generally do NOT contain inert or noble gases as many people claim. The color and effects of the discharge are created from normal air at various vacuums. While sparks in normal air are purple, these sparks spread from red, violet, blue, lavender, and white as the vacuum inside of the tube increases:

Some manufacturers did use Neon in their electrodes, but this was mainly limited to European devices from the 1930s and later. Most American devices used simply normal air at various degrees of vacuum. The photos above are of the same glass tube, however the vacuum is steadily increasing from left to right. If the white vacuum on the far right was evacuated even more, the various discharges of Crookes and Röntgen would start to appear.

One of the last misconceptions about Violet Rays is that they emit ultraviolet radiation. This is also false. Quartz Glass is the only glass that can transmit Ultraviolet Radiation, and most Violet Ray electrodes are made from Pyrex or Soda Lime Glass. The only Ultraviolet Radiation emitted from these machines is from the actual sparks generated from them. All electric sparks produce Ultraviolet Radiation to some extent. The only effect of the gas, pressure, or vacuum inside of glass the electrodes is the actual resistance of the vacuum electrode and this effects the characteristics of the electricity conducted through them. As the old manuals boast, “the electrodes diffuse the electricity”. In other words, they remove the harshness associated with a direct electrical spark to the body.

So who invented these electrodes? Frederick Finch Strong invented the glass vacuum electrode around 1896. This concept was perfected by people such as Arnold Snow. Many physicians adopted their own form of electrodes, and books from authors such as Eberhart or Tousey depict some of these images.

Violet Ray Applications

So what are the authentic use of Violet Ray machines? Mainly (as the original units) for treating minor skin conditions. Ozone is germicidal (kills bacteria) and high frequency currents are dehydrating for the skin. Acne or similar conditions are often improved by the nature of these applications. Also, figuration or cold cautery is used with these devices - the ability of a small electric spark to destroy tissue. This is one method of removing warts.

The mild heating effects of these devices (which are minute compared to Diathermy) has the ability of relieving pain to a small extent. Unlike external heating pads, Violet Ray electrode heat the body from the inside-out, which is often more beneficial.

On the subject of applications of these currents, it should be noted that treatments rarely consist of electrical sparks being applied to the skin. This can cause unpleasant burns. Whenever early books mention “a quarter inch spark” or “a half inch spark” for various ailments, it is meant that the machine be adjusted to produce such a spark, and the glass electrode applied directly to the body thereafter.

On a lighter note, “Fun With a Violet Ray” (Thomas Malloy’s 1931 article in Science and Invention) highlights some nonmedical, spectacular demonstrations you can do to amaze and entertain your friends!

NOTE: No person with a pacemaker should be allowed near a Violet Ray machine, the effects could be fatal. Violet Ray devices can and will interfere with nearby electronics.


Downloads for this article are available to members.
Log in or join today to access all content.