However their largest use was as the ignition coil or spark coil in the ignition system of internal combustion engines, where they are still used, although the interrupter contacts are now replaced by solid state switches. A smaller version is used to trigger the flash tubes used in cameras and strobe lights.
|
|
William Shakespeare and Leonardo da Vinci were considered amateur artists and autodidacts in their fields of study. Radio astronomy was founded by Grote Reber, an amateur radio operator. Radio itself was greatly advanced by Guglielmo Marconi, a young Italian gentleman who started out by tinkering with a coherer and a spark coil as an amateur electrician. Pierre de Fermat was a highly influential mathematician whose primary vocation was law.
|
|
For example, in December 1916 QST magazine, an amateur operator working on long distance message passing describes one way to avoid interference was to send messages "...on Thursday nights, when the children and spark coil 'hams' are tucked up in bed" (a spark coil was an unsophisticated radio transmitter, made from an automobile ignition coil, that produced noisy interference). But only a few months later, in an indication of the changing use of the term among amateurs, a QST writer uses it in a clearly complimentary manner, saying that a particular 16-year- old amateur operator "...is the equal of a ham gaining five years of experience by hard luck." Use of "ham" as a slur by professionals continued, however. A letter from a Western Union Telegraph Company employee, printed in the December 1919 edition QST, showed familiarity with the word's negative connotations, expressing concern that "Many unknowing land wire telegraphers, hearing the word 'amateur' applied to men connected with wireless, regard him as a 'ham' or 'lid'".
|
|
Aceon Bright Ignition Coil Bosch ignition coil in a Saab 96. Dual ignition coils (blue cylinders, top of picture) on a Saab 92. An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system that transforms the battery's voltage to the thousands of volts needed to create an electric spark in the spark plugs to ignite the fuel. Some coils have an internal resistor, while others rely on a resistor wire or an external resistor to limit the current flowing into the coil from the car's 12-volt supply.
|
|
Antique induction coil used in schools, from around 1900, Bremerhaven, Germany Induction coil showing construction, from 1920. An induction coil or "spark coil" (archaically known as an inductorium or Ruhmkorff coil after Heinrich Rühmkorff) is a type of electrical transformer used to produce high-voltage pulses from a low-voltage direct current (DC) supply.John Archibald Fleming p.98 To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called an interrupter.
|
|
That model used battery-operated spark-coil ignition; widely sold mid-century models created a spark as modern lighters do using ferrocerium. Another key feature of these devices as toys, is that acetylene explosions, compared to gunpowder, were much safer. The low density of the acetylene/air mixture is such that the total combustion energy is quite low and there is no recoil and little stress on the chamber holding the explosion, even if the outlet barrel was partly blocked. The original toys were brittle cast iron; the company even demonstrated cannons made of glass to show that there was no likelihood of dangerous fracture.
|
|
The Freeman transmitter broke down — in a fit of rage, de Forest threw it overboard — and had to be replaced by an ordinary spark coil. Even worse, the American Wireless Telephone and Telegraph Company, which claimed its ownership of Amos Dolbear's 1886 patent for wireless communication meant it held a monopoly for all wireless communication in the United States, had also set up a powerful transmitter. None of these companies had effective tuning for their transmitters, so only one could transmit at a time without causing mutual interference. Although an attempt was made to have the three systems avoid conflicts by rotating operations over five-minute intervals, the agreement broke down, resulting in chaos as the simultaneous transmissions clashed with each other.
|
|
In this mode of operation, the coil would "buzz" continuously, producing a constant train of sparks. The entire apparatus was known as the 'Model T spark coil' (in contrast to the modern ignition coil which is only the actual coil component of the system). Long after the demise of the Model T as transportation they remained a popular self-contained source of high voltage for electrical home experimenters, appearing in articles in magazines such as Popular Mechanics and projects for school science fairs as late as the early 1960s. In the UK these devices were commonly known as trembler coils and were popular in cars pre-1910, and also in commercial vehicles with large engines until around 1925 to ease starting.
|
|
With radio research his main priority, de Forest next took a night teaching position at the Lewis Institute, which freed him to conduct experiments at the Armour Institute.The two Institutes merged in 1940 to become the Illinois Institute of Technology physics department. By 1900, using a spark-coil transmitter and his responder receiver, de Forest expanded his transmitting range to about seven kilometers (four miles). Professor Clarence Freeman of the Armour Institute became interested in de Forest's work and developed a new type of spark transmitter. De Forest soon felt that Smythe and Freeman were holding him back, so in the fall of 1901 he made the bold decision to go to New York to compete directly with Marconi in transmitting race results for the International Yacht races.
|
|
The Model T magneto (built into the flywheel) differed from modern implementations by not providing high voltage directly at the output; the maximum voltage produced was about 30 volts, and therefore also had to be run through the spark coil to provide high enough voltage for ignition, as described above, although the coil would not "buzz" continuously in this case, only going through one cycle per spark. In either case, the low voltage was switched to the appropriate spark plug by the timer mounted on the front of the engine. This performed the equivalent function to the modern distributor, although by directing the low voltage, not the high voltage as for the distributor. The ignition timing was adjustable by rotating this mechanism through a lever mounted on the steering column.
|
|