The Transformer (Part 1)

Simply put, a transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors i.e. coils—that's plural.  Because of that magic word... "coils" this post relates to my series on induction here. I'll try not to repeat myself too much. Try to think of this as a sequel. We use transformers to step up or step down the voltage in a circuit, or to convert AC power to DC power. (like wall warts)  This is more important than you think. Everything in the world runs on AC power, and that requires DC to AC conversions.) In 1802, Humphry Davy invented the first light bulb and it began an international human obsession with lighting up everything.The transformer was destined for ubiquity.

Most sources agree that the first transformer was an induction coil, invented by Rev. Nicholas Callan in 1836. His was not even the first induction coil with two coils. But he was probably the first experimenter to figure out that the relationship between the primary and secondary winding and the number of turns of wire. (That's directly proportional by the way. The more turns the secondary winding has than the primary coil, the more EMF it produces. But Callan wasn't using his coil as a transformer. He was using it to increase the voltage output from a battery. It was a critical step, but not exactly a modern transformer. It might have been even more important in a way that Callan suggested in an 1857 that joining together the secondary circuits of a number of coils might be able to power an arc light. That got some peoples attention, possibly even Mr. Bláthy.

The first big name in transformers is Ottó Titusz Bláthy. The term "transformer" itself is generally credited to Ottó Bláthy.  He was an electrical engineer in Hungary who started his significant work around 1880. He was employed at the Ganz Works in Budapest. they built ships, submarines, cars, planes and even power plants so Bláthy  had access to a big shop. He worked with Miksa Déri and Károly Zipernowsky in developing the ZBD model alternating-current transformer in 1885. This was a toroidal-type transformer for use in their incandescent AC powered lighting.

They were overcoming the short comings of DC: heat loss, distance limitations, etc.They developed an array of improvements to make a primitive transformer work better.  Zipernowsky  had developed the shunts and  Déri largely performed the testing. But our man Otto here designed it's iron core. He was their youngest engineer, just 22 years old. The end result was a set of 75 transformers that stepped down 1.35 kV to power over a thousand light bulbs. They had started the project with a Gaulard-Gibbs transformer. More on that tomorrow...

The Induction Coil (Part 3)

It's hard to understand why Ruhmkorff is most often credited with the invention of the induction coil in 1851. Joseph Henry invented it in 1831. Then both Charles Page, and Nicholas Callan invented it in 1836. It's especially strange since Ruhmkorff based the design he patented on a different earlier induction coil made by Edward Samuel Ritchie. It relates back to that cranking mechanism. Let me back up to Callan. You may recall in Part 2 he built what he called a "repeater." That was a mechanism that could make and break the electrical circuit in a cycle. What was important about that was that it increased the power of the output spark. Since electric motors did not yet exist everything that moved moved by wind, water, steam, gravity or muscle. So all these devices needed to be cranked.

The earliest cranked inductor was probably built by a French engineer named  Antoine-Hippolyte Pixii. He built a simple dynamo based a description of Faraday's 1831 device. Faraday had mounted a copper disk on an axle and spun it between the poles of a magnet. This generated an electric current. In 1832 Pixii modified that so that the magnet was rotated by a hand crank and he positioned it such that its north and south poles passed over two pieces of iron wrapped with coiled wire. It's those coils of wire that are so important. Pixii even determined that each pole produced a separate pulse of current i.e. This was an AC device! Pixii had previously been hired by both Andre
Ampere and Claude Pouilett to build their own instruments.  So this was not his first foray.

Joseph Saxton of Philadelphia built a unit based on the Pixii design. His first devices dates to 1832, but he had but the basic design to paper at least a year earlier. He reversed the mechanism instead spinning the horseshoe magnet and leaving the coils stationary. His went through several revisions, but the basic device was described in detail in his 1874 memoir read before the National Sciences Academy by none other than Joseph Henry.

"Mr. Saxton fastened the U to a revolving axis passing through its crown, to which a rapid rotation could be given by means of a driving wheel and pulley. In order, however, to obtain manifestations of the induced currents produced in the copper-wire, the two ends of the coils were so soldered together, as to give a single current in one direction through the entire length of the coils. One of the remaining ends was then permanently soldered to a circular disk fastened concentrically to the revolving axis by an insulating collar, with its plane perpendicular to it. This plate dipped into a cup of mercury. The other end of the wire was soldered directly to the revolving shaft or axis."

This cranking and rotating of the magnet gets closer and closer to a dynamo. A is just an electrical generator that uses rotating coils of wire and magnets to convert mechanical rotation into electric current. It's output is governed by Faraday's law. That law is as follows: The EMF generated is proportional to the rate of change of the magnetic flux. That's exactly what Callan observed. The faster he could make and break the circuit, the greater the current output by his cranking. All this leaves me with one big question. How do we get from the 1836 "invention" of the induction coil to the 1856 "invention" of the induction coil?

In 1835 Edward Samuel Ritchie and Edmond Clarke were fighting it out over who made the better induction coil yet both were based on the work of Pixii. In 1838 Daniel Davis made a slightly modified machine based on the published accounts of Page and Sturgeon. Davis actually published a 72-page catalog filled with  models of home electrical induction devices. These were presumably for the purpose of shocking oneself or ones friends and family for "medical" purposes or just the schadenfreude. In 1839 a German doctor named Christian Neef et De La Rive innovated a new make/break mechanism to increase output.  It was a hammer break mechanism. It consisted of a spring contact that operated automatically to break the electrical circuit when displaced by the action of the electromagnet. William Sturgeon published the first English version of the Neef "repeater" in 1839. Interestingly Page credits the so-called Neef-Hammer to Prof James William McGauley. It then further states that Ruhmkorff stole McGauley's circuit breaker.

After all of that progress, there is still a 18-year gap still remaining between that last material improvement and Ruhmkorff "invention" of the induction coil. In truth Major improvements essentially stop before 1940. Even circuit breakers have little improvement until Foucault  in 1856. Golding Bird made some minor refinements to McGauley's device in 1838. Ernst Neeff also gets a mention for an equally minor adjustment in 1839. In 1842 W.T. Henley proffered a coil that worked ran on a clock-work mechanism. But that mechanism was actually from Rev. F. Lockey. It was more of an amalgam than an invention. In 1842 Page was discharging electrical flashes in vacuum tubes and working on electric motors.

The reason that improvements stopped is that the device had been "perfected." It was fully functional. It was moving out of the lab and into commercial use.  That's where it remained for almost 2 decades. By 1843 both Thomas Wright and Neef were boiling water with an induction coil. In the year 1850 Werner Siemens patented a dial telegraph and an alarm for it which used an automatic vibratory circuit breaker which also drew from McGauley's circuit breaker. All manner of devices were built, stocked shipped and sold: telegraphs, alarms, bells, buzzers, X-ray devices, electroshock.. all manner of consumer and medical devices used induction coils. All these products and services apparently awaited their retroactive post-Ruhmkorff invention.

The Induction Coil (Part 2)

Not to diminish the roles of Daniel Davis, Benjamin Pike, S.B. Smith, Neef, Wagner, James Foster, and others but they don't really matter much in the narrow scope of this little article. I refer to them only as necessary. I'm skipping ahead to Callan. What's unique about the development of the induction coil is that much of it's improvements happened concurrently, not sequentially. Try to remember that as I mercilessly skip back and forth in the chronology.An 1867 history book summarized my dilemma.

"During that period a very great number of induction coils and circuit-breakers were announced, but no importance or interest seems to have been attached to this branch of the subject. We had the Masson coil, the Neef coil, the Callan coils, the Sturgeon coils, the McGauley coil, the Dr. Bird coil, the Lockey, the Nesbitt, the Clarke, the Roberts, the Bachhoff'ner, and many other coils, all represented as being very potent in giving shocks; but, beyond the intensity required for this purpose, not a single inquiry is recorded."

Of all those, only Callhan is really material as he's directly connected to the other main characters in my narrative.  So let us rewind to 1836. Nicholas J. Callan was was a priest and scientist like Murgas I suppose but clearly more disciplined. He was Professor at Maynooth College near Dublin and most of his work I refer to occurred there.  In 1936 he was 37 years old, and had just developed his first induction coil...it was within months of the one Page invented. In an 1836 issue of the Annals of Electricity His induction coil was described as a transformer. It was a 2-foot long bar of soft iron bent into a horse shoe shape and wrapped with two separate windings: the first was about 200 ft of thick copper wire, and the second outer layer with thin copper wire. He thought it was an electromagnet, much like the one Joseph Henry had made in 1831. More here and here.

But like the others, the first thing he set about doing was shocking himself.  He connected a battery to both ends of the primary coil.  He discovered that when the battery contact was broken, a shock could be felt between the first terminal of the primary coil and the unconnected end of the secondary coil.  But he did something interesting with it. He engineered a way to break and reconnect that circuit quickly with a device he called a "repeater." He used a hand crank that turned a cog wheel that connected to a horizontal copper rod via an escapement that made connection with the wheel. With it he was able to break and make the circuit over 500 times a second. This generated some massive sparks. He experimented with more and more powerful battery configurations until his peers were afraid of his works. He described it  in the 1836 July-December issue of the London and Edinburgh Journal of Science.

"By experiments on the best means of obtaining the shock from the electromagnet, I have found that the shock increases, within certain limits, with the length and thinness of the bar of soft iron, and with the length of the helical coil, as far perhaps as 200 feet, and in proportion, or nearly in proportion, to the number of plates in the voltaic battery from which the current of electricity is passed through the helix. The shock does not increase in proportion to the number of plates unless they are large. ... the shock was so strong that a person who took it felt the effects of it for several days. ... I could not induce any one to take the shock from the electromagnet when a greater number than 16 of our large plates were used."

Later  Callan's experimented with an induction coil using toughs of mercury just like Page. His was arranged with a wire that was rocked repeatedly into the mercury. Ultimately Callan determined (at least tactility) that the faster he interrupted the current, the bigger the spark. In 1837 he build a large scale induction device It generated 15-inch sparks, which are estimated to have produced up to 600,000 volts which was the largest artificial bolt of electricity ever made.

He didn't toil in total obscurity. Callan did publish papers on his primary works allowing others to build on them. In 1837, Callan sent a replica of his coil to William Sturgeon and it was exhibited to members of the Electrical Society.  Sturgeon (as noted previously) may have invented the first electromagnet in 1825. His was a horseshoe-shaped piece of iron that wrapped with a loosely wound copper coil. Sound familiar?  Well as much as Sturgeon had been inspired by Page, he also has an earlier position on this Mobius strip. In 1830, Joseph Henry (of the Henry Calorimeter) held a demonstration Sturgeon's electromagnet.  He used a battery to send an electronic current over one mile of wire activating an electromagnet which triggered an armature that then struck a bell.  I don't want to overstate things.. but that is the basic mechanism in the telegraph...

Despite the reception of his 1837 paper, he did not publish often. And because his college was a theological school, his colleagues often tried to dissuade him in science pursuits. He experimented with galvanization and different batteries but did gradually stray away from his greatest contributions. He died in 1864, about 40 years before he'd be recognized scientifically for his contributions.