Doc Kauffman (born Clayton Orr Kauffman, died June 26, 1990) was a lap steel guitar, electric guitar engineer, inventor & pinoeer of the worlds first patented guitar vibrola. The patent for "Apparatus for producing tremolo effects" was applied for in 1928 and officially granted to Doc Kauffman on January 5th, 1932. 
During the 1930s, Doc Kauffman served as chief electric guitars designer for Rickenbacker. Having invented and patented the first mechanical vibrato unit, Kauffman was able to implement his patented creation onto the Electro-Spanish Ken Roberts model as the instruments standard stock bridge. This addition would earn the rank as the first vibrola ever to be equipped, as a standard stock-option, on an electrified guitar. This would set precedence for the future development of electric guitars into the 1940s & 1950s. Notably, the Fender Stratocaster and Bigsby vibrato tailpieces. 
In the early 1940's, Doc Kauffman & Leo Fender would enter a business partnership, forming the K&F company in 1945. K&F only lasted 3 years, having produced amplifiers and lap steel guitars in small quantities. After Kauffman left, K&F transformed to Fender. Doc Kauffman & Leo Fender remained friends until Doc's death in 1990. Doc Kauffman considered Leo Fender such a close friend, Leo was listed as next to kin, after Doc's children, in Doc's final will & testament. Leo died just one year after Doc in 1991. 
Les Paul and Doc Kauffman struck a friendship in the 1930s. Les would later utilize the Kauffman Vibrola on his prototype "Log" guitars developed in the 1940s. Les favored the Kauffman vibrola to such a degree, he removed the stock bridge on his brand-new 1952 signature Gibson model and reinstalled the Kauffman vibrola. 
An electric guitar is a guitar that uses one or more pickups to convert the vibration of its strings into electrical signals. The vibration occurs when a guitar player strums, plucks, fingerpicks, slaps or taps the strings. The pickup generally uses electromagnetic induction to create this signal, which being relatively weak is fed into a guitar amplifier before being sent to the speaker(s), which converts it into audible sound.
The electric signal can be electronically altered to change the timbre of the sound. Often, the signal is modified using effects such as reverb, distortion and "overdrive"; the latter is considered to be a key element of electric blues guitar music and rock guitar playing.
Invented in 1931, the electric guitar was adopted by jazz guitar players, who wanted to play single-note guitar solos in large big band ensembles. Early proponents of the electric guitar on record include Les Paul, Lonnie Johnson, Sister Rosetta Tharpe, T-Bone Walker, and Charlie Christian. During the 1950s and 1960s, the electric guitar became the most important instrument in popular music. It has evolved into an instrument that is capable of a multitude of sounds and styles in genres ranging from pop and rock to country music, blues and jazz. It served as a major component in the development of electric blues, rock and roll, rock music, heavy metal music and many other genres of music.
Electric guitar design and construction varies greatly in the shape of the body and the configuration of the neck, bridge, and pickups. Guitars may have a fixed bridge or a spring-loaded hinged bridge, which lets players "bend" the pitch of notes or chords up or down, or perform vibrato effects. The sound of an electric guitar can be modified by new playing techniques such as string bending, tapping, and hammering-on, using audio feedback, or slide guitar playing.
There are several types of electric guitar, including: the solid-body guitar; various types of hollow-body guitars; the six-string guitar (the most common type), which is usually tuned E, B, G, D, A, E, from highest to lowest strings; the seven-string guitar, which typically adds a low B string below the low E; and the twelve-string guitar, which has six pairs of strings.
In pop and rock music, the electric guitar is often used in two roles: as a rhythm guitar, which plays the chord sequences or progressions, and riffs, and sets the beat (as part of a rhythm section); and as a lead guitar, which provides instrumental melody lines, melodic instrumental fill passages, and solos. In a small group, such as a power trio, one guitarist switches between both roles. In large rock and metal bands, there is often a rhythm guitarist and a lead guitarist.Electric guitar design
Electric guitar design is a type of industrial design where the looks and efficiency of the shape as well as the acoustical aspects of the guitar are important factors. In the past many guitars have been designed with all kinds of odd shapes as well as very practical and convenient solutions to improve the usability of the object.Electro-Spanish Ken Roberts
Manufactured by Rickenbacker, the Electro-Spanish Ken Roberts is considered the pioneering "grandfather" to the modern electric guitar as it was the first commercially produced full, twenty-five inch scale electric guitar ever made. The Electro-Spanish Ken Roberts holds the current world record for the highest price paid for a guitar, after selling in 2017 for $7.5 million.Electro-Spanish Model B
Electro-Spanish Model B
The Electro-Spanish Model B was the worlds first production, solid body (Bakelite) electrified lap steel guitar, officially released in 1935 by Rickenbacker. Commercially, it was the most successful musical instrument manufactured by Rickenbacker. Though not entirely solid - it had thick plastic (Bakelite) walls and a detachable Spanish neck. The instrument was created to eliminate the feedback found in conventional electrification of stringed instruments.The "Electro-Spanish Model B" set the stage for solid body guitars to develop; including the notable "Les Paul" whose electric solid-body would reach mainstream notoriety in 1952, produced by Gibson Guitar Corporation.Fender Musical Instruments Corporation
Fender Musical Instruments Corporation (FMIC, or simply Fender) is an American manufacturer of stringed instruments and amplifiers. Fender produces acoustic guitars, electric basses, bass amplifiers and public address equipment, but is best known for its solid-body electric guitars and bass guitars, particularly the Stratocaster, Telecaster, Precision Bass, and the Jazz Bass. The company was founded in Fullerton, California, by Clarence Leonidas "Leo" Fender in 1946. Its headquarters are in Scottsdale, Arizona.
FMIC is a privately held corporation, with Andy Mooney serving as the Chief Executive Officer (CEO). The company filed for an initial public offering in March 2012, but this was withdrawn five months later. In addition to its Scottsdale headquarters, Fender has manufacturing facilities in Corona, California (US) and Ensenada, Baja California (Mexico).As of July 10, 2012, the majority shareholders of Fender were the private equity firm of Weston Presidio (43%), Japanese music distributors Yamano Music (14%) and Kanda Shokai (13%) and Servco Pacific (5%). In December 2012, TPG Growth (the middle market and growth equity investment platform of TPG Capital) and Servco Pacific took control of the company after acquiring the shares held by Weston Presidio.Fender Telecaster
The Fender Telecaster, colloquially known as the Tele , is the world's first commercially successful solid-body electric guitar.
Its simple yet effective design and revolutionary sound broke ground and set trends in electric guitar manufacturing and popular music. Introduced for national distribution as the Broadcaster in the autumn of 1950, it was the first guitar of its kind manufactured on a substantial scale and has been in continuous production in one form or another since its first incarnation.Just like the Fender Stratocaster, the Telecaster is also a versatile guitar, usable for most styles of music and has been used in many genres, including country, reggae, rock, pop, folk, soul, rhythm and blues, blues, jazz, punk, and heavy metal.Fender amplifier
Leo Fender began building guitar amplifiers before he started manufacturing electric guitars. The first of these were the K&F models, produced between 1945 and 1946. The early K&F and Fender amplifiers relied upon vacuum tube circuitry, with the company adding solid-state models in the late 1960s.Leo Fender
Clarence Leonidas "Leo" Fender (August 10, 1909 – March 21, 1991) was an American inventor who founded Fender Electric Instrument Manufacturing Company, or "Fender" for short. In January 1965, he sold the company to CBS and later founded two other musical instrument companies, Music Man and G&L Musical Instruments.
The guitars, bass guitars, and amplifiers he designed from the 1940s on are still widely used: the Fender Telecaster (1950) was the first mass-produced solid-body electric guitar; the Fender Stratocaster (1954) is among the world's most iconic electric guitars; the Fender Precision Bass (1951) set the standard for electric bass guitars, and the Fender Bassman amplifier, popular enough in its own right, became the basis for later amplifiers (notably by Marshall and Mesa Boogie) that dominated rock and roll music. Leo Fender was inducted into the Rock and Roll Hall of Fame in 1992: a unique achievement given that he never learned to play the instruments that he made a career of making.Rickenbacker
Rickenbacker International Corporation is an electric string instrument manufacturer based in Santa Ana, California. The company is credited as the first known maker of electric guitars —in 1932—and eventually produced a range of electric guitars and bass guitars. Known for their distinctive jangle and chime, Rickenbacker twelve string guitars were favored by The Beatles, Roger McGuinn of The Byrds, and Gerry Marsden of Gerry and the Pacemakers. Well known players of the six string include John Fogerty of Creedence Clearwater Revival, John Kay of Steppenwolf, Tom Petty of Tom Petty and the Heartbreakers [Everson maré] of [os serranos]Vibrato systems for guitar
A vibrato system on a guitar is a mechanical device used to temporarily change the pitch of the strings. Instruments without a vibrato have other bridge and tailpiece systems. They add vibrato to the sound by changing the tension of the strings, typically at the bridge or tailpiece of an electric guitar using a controlling lever (alternately referred to as a whammy bar, vibrato bar, or incorrectly as a tremolo arm). The lever enables the player to quickly and temporarily vary the tension and sometimes length of the strings, changing the pitch to create a vibrato, portamento, or pitch bend effect.
The pitch-bending effects have become an important part of many styles, allowing creation of sounds that could not be played without the device, such as the 1980s-era shred guitar "dive bombing" effect.
The mechanical vibrato systems began as a device for more easily producing the vibrato effects that blues and jazz guitarists had achieved on arch top guitars by manipulating the tailpiece with their picking hand. Guitar makers developed a variety of vibrato systems since the 1920s.A vibrato-equipped guitar is more difficult to re-string and tune than a fixed-tailpiece guitar.Since the regular appearance of mechanical vibrato systems in the 1950s, many guitarists have used them—from Chet Atkins to Duane Eddy and the surf music of The Ventures, The Shadows, and Dick Dale. In the 1960s and 1970s, Jimi Hendrix, Jeff Beck, David Gilmour, Ritchie Blackmore, Jimmy Page, and Frank Zappa used vibrato arms for more pronounced effects. In the 1980s, shred guitarists Eddie Van Halen, Eric Johnson, Joe Satriani and Steve Vai, and metal guitarists Ritchie Blackmore, Kirk Hammett, Terje Rypdal, David Torn and David Duhig used vibrato in a range of metal-influenced styles.