Rudolf Goldschmidt (1876—1950) was a German
engineer
Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the l ...
and
inventor
An invention is a unique or novel device, method, composition, idea or process. An invention may be an improvement upon a machine, product, or process for increasing efficiency or lowering cost. It may also be an entirely new concept. If an ...
, best known for the development of the
Goldschmidt alternator
The Goldschmidt alternator or reflector alternator, invented in 1908 by German engineer Rudolph Goldschmidt, was a rotating machine which generated radio frequency alternating current and was used as a radio transmitter. Radio alternators like ...
radio transmitter, and the
tone wheel receiver.
Biography
Early life
Goldschmidt was born on March 19, 1876 in
Neubukow
Neubukow (literally "New Bukov", where 'Bukov' is a Polabian adjective from "beech tree") is a town in the Rostock district, in Mecklenburg-Western Pomerania, Germany. It is situated 18 km southwest of Bad Doberan, and 21 km northeast o ...
, Mecklenburg, Germany, and grew up in that country. He studied engineering at Charlottenburg and Darmstadt Technical High School, and was awarded an electrical engineer degree at
Technische Hochschule Darmstadt in January 1898. Beginning in 1899 he published numerous articles on various branches of electrical engineering. In 1900 he received a college and traveling scholarship, and visited engineering works in Belgium, England, and France. Later that year he was appointed engineer in the laboratory of the Allgemeine Elektricitäts-Gesellschaft AG (AEG) in Berlin. In 1901-1902 he was chief laboratory engineer and designer for Kolben and Company, Ltd., in Prague. He came to England in connection with the Willesden Electricity Supply Station, and was later appointed chief engineer to Crompton and Company in Chelmsford. In 1905 he joined the Westinghouse Company at Manchester.
["GOLDSCHMIDT, Professor Dr. Rudolf"]
(biography), ''The Year-book of Wireless Telegraphy & Telephony'' (1914), pages 707-708.
After passing the German ''abitur''-examination he was awarded an Engineering doctorate degree. In 1907 he returned to Germany as lecturer at Darmstadt Technical College, began working as a consulting engineer, and worked on several inventions, primarily with designing high-frequency alternator transmitters for radio-telegraphy. In 1911 he became manager of Hochfrequenz-Maschinen Aktiengesellschaft für drahtlose Telegraphie (HOMAG) in Berlin, a company formed to promote his radio inventions.
In 1905 Goldschmidt married journalist Hella Gimpel (1883–1933), sister of the painter , and subsequently had three sons and a daughter.
Radio inventions
In 1908 he developed the
Goldschmidt alternator
The Goldschmidt alternator or reflector alternator, invented in 1908 by German engineer Rudolph Goldschmidt, was a rotating machine which generated radio frequency alternating current and was used as a radio transmitter. Radio alternators like ...
, an early
radio transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...
that employed rotating elements and was one of the first
continuous wave
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle ...
transmitters. These were manufactured by the HOMAG company for use in high power
longwave
In radio, longwave, long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with wavelengths longer than what was originally called the medium-wave broadcasting band. The term is historic, dating from the e ...
radio stations conducting intercontinental
radiotelegraph
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for t ...
traffic. Large 100-kilowatt Goldschmidt transmitters in Eilvese, Germany and Tuckerton, New Jersey, USA were used in the first direct communications link between Germany and the United States, which was inaugurated on 19 June 1914 with a ceremonial exchange of telegrams between
Kaiser Wilhelm II
Wilhelm II (Friedrich Wilhelm Viktor Albert; 27 January 18594 June 1941) was the last German Emperor (german: Kaiser) and List of monarchs of Prussia, King of Prussia, reigning from 15 June 1888 until Abdication of Wilhelm II, his abdication on 9 ...
and President
Woodrow Wilson
Thomas Woodrow Wilson (December 28, 1856February 3, 1924) was an American politician and academic who served as the 28th president of the United States from 1913 to 1921. A member of the Democratic Party, Wilson served as the president of ...
. Alternator radio transmitters were used into the 1920s, when they were replaced by
vacuum tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied.
The type kn ...
transmitters.
He also invented the Goldschmidt
tone wheel, a mechanical device used in early
radio receiver
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. Th ...
s to receive the new continuous wave signals. The first type of radio transmitter, the
spark-gap transmitter
A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark."Radio Transmitters, Early" in Spark-gap transmitters were the first type of radio transmitter, and were the main type use ...
, produced strings of
damped wave
Damping is an influence within or upon an oscillatory system that has the effect of reducing or preventing its oscillation. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation. Examples inc ...
s that were heard as a buzz or tone in a receiver, so the radio wave pulses used to transmit
Morse code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of ...
were audible as "beeps". However, the unmodulated signals produced by early continuous wave (also known as "undamped") transmitters like the Goldschmidt alternator were inaudible in receivers designed for reception of spark transmissions. To make continuous wave signals audible, the tone wheel receiver used the
heterodyne
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called ''heterodyning'', which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is us ...
principle to convert the received transmission into an audio frequency tone.
The tone wheel was a disk with contacts around the rim, spun by a small electric motor, which interrupted the incoming radio signal at a slightly different radio frequency rate than the one used by the transmission. The tone wheel acted as a simple
beat frequency oscillator
In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy ( CW) transmissions to make them audible. The signal from the BFO is mixed with the recei ...
(BFO), and its radio frequency, when combined with the received signal, created an audible "beat" (heterodyne) tone with a frequency that was the difference between the two rates. For example, if the transmitted frequency was 60,000 Hz, the tone wheel could be adjusted to 59,000 Hz, creating a 1,000 Hz tone which could be heard in the earphones as a musical "beep" whenever the carrier was present.
The tone wheel was used for a short period until the 1920s, when it was replaced by the
vacuum tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied.
The type kn ...
regenerative receiver
A regenerative circuit is an amplifier circuit that employs positive feedback (also known as regeneration or reaction). Some of the output of the amplifying device is applied back to its input so as to add to the input signal, increasing the am ...
. Later the tone wheel was used as a musical tone generating device in early
electronic organ
An electric organ, also known as electronic organ, is an electronic keyboard instrument which was derived from the harmonium, pipe organ and theatre organ. Originally designed to imitate their sound, or orchestral sounds, it has since developed ...
s.
Later life
During the 1920s, Goldschmidt directed an industrial research lab in Berlin. Here he met
Albert Einstein
Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...
. In 1928, a singer with whom the physicist was acquainted suffered a hearing loss, which set Einstein to thinking about hearing aids. Soon he had an idea and asked Goldschmidt to help him develop a working model. A German patent was issued to Goldschmidt and Einstein on 10 January 1934.
"Albert Einstein's Forgotten Inventions"
by Ross Pomeroy, February 8, 2018 (realclearscience.com)
In 1934, Goldschmidt and his children emigrated to England. He kept up his correspondence with Einstein until his death in Bournemouth
Bournemouth () is a coastal resort town in the Bournemouth, Christchurch and Poole council area of Dorset, England. At the 2011 census, the town had a population of 183,491, making it the largest town in Dorset. It is situated on the Southern ...
in 1950.
References
* Appendix: Einstein's collaborators
* «Rudolf Goldschmidt» (entry), in: ''100 jüdische Persönlichkeiten aus Mecklenburg-Vorpommern: ein Begleiter zur Ausstellung des Max-Samuel-Hauses 22. Mai bis 22. November 2003'', , Stiftung Begegnungsstätte für Jüdische Geschichte und Kultur in Rostock ostock Jewish Heritage Centre(ed.), Frank Schröder (1958-2004), Axel Attula, Christine Gundlach et al., (=Schriften aus dem Max-Samuel-Haus; vol. 4), Rostock: Weidner, 2003, pp. 65seq.
{{DEFAULTSORT:Goldschmidt, Rudolf
1876 births
1950 deaths
Engineers from Mecklenburg-Western Pomerania
Otology
20th-century German inventors
Technische Universität Darmstadt faculty
Technische Universität Darmstadt alumni
People from Rostock (district)
German emigrants to the United Kingdom