Eduard Karplus
Eduard Karplus (September 7, 1899 – August ?, 1979) was an Austrian-born engineer, best known as the inventor of the Variac.
Karplus was born in Hinterbrühl, Austria, the second child of Johann Paul Karplus, a neurophysiologist and psychiatrist, and Valerie von Lieben, a sister of physicist Robert von Lieben.
He graduated from the Vienna University of Technology in 1923. From 1923 to 1929, he was employed in the RF laboratories of C. Lorenz AG, Berlin, Germany, where he worked on mobile high-frequency communication equipment.
In 1930, Eduard Karplus joined the engineering staff of General Radio Corporation in Cambridge, Massachusetts, where he designed and developed measuring instruments, including work on early models of oscilloscopes.
Karplus' best-known invention is the development of the first practical, continuously adjustable variable-ratio autotransformer, which General Radio introduced under the "Variac" brand name (short for "variable AC") in 1933. In the 1940s and 1950, Karplus continued to work on microwave topics such as signal generators, including the design of the GR-874 hermaphroditic high-frequency connector.
Links
- Eduard Karplus @ Wikipedia
- Eduard Karplus, Electron Oscillations. General Radio Experimenter, Vol.5 No.12 May 1931, p.1 (on Barkhausen-Kurz oscillations)
Patents
- US Patent 1856709, Eduard Karplus, Coupling arrangement for compensated high frequency amplifiers. Filed 1928-01-09; Granted 1932-05-03
- US Patent 1811357, Eduard Karplus, Wireless signaling apparatus. Filed 1929-03-11; Granted 1931-06-23
- US Patent 1916224, Eduard Karplus, Self-contained oscillator tube. Filed 1929-12-09; Granted 1933-07-04
- US Patent 2009013, Eduard Karplus, Alternating-current apparatus. Filed 1934-06-01; Granted 1935-07-23 (the Variac patent)
- US Patent 2367681, Eduard Karplus, Ultra-high-frequency tuning apparatus. Filed 1941-12-10; Granted 1945-01-23
- US Patent 2578429, Eduard Karplus, Ultrahigh-frequency tuning apparatus. Filed 1945-12-19; Granted 1951-12-11
Instruments
| Instrument | Description | Literature link |
|---|---|---|
| 419-A | Rectifier-Type Wavemeter | 1931-11 |
| 566-A | Wavemeter | 1931-10 |
| 687-A | Oscilloscope | 1934 (GR Museum) |
| 720-A | Heterodyne Frequency Meter | 1945-07 |
| 758-A | Wavemeter | 1940-08 |
| 857-A | UHF Oscillator | 1944-11 |
| 874-MR | Mixer | 1950-05 |
| 1021-A | UHF Standard-Signal Generator | 1950-03 |
| 1025-A | Swept Frequency Generator | 1963-01 |
| 1208-A | Unit Oscillator | 1950-05 |
| 1208-B | Unit Oscillator | 1954-04 |
| 1208-C | Unit Oscillator | 1965-06 |
| 1209-A | Unit Oscillator | 1950-05 |
| 1209-B | Unit Oscillator | 1954-04 |
| 1209-C | Unit Oscillator | 1965-06 |
| 1218-A | Unit Oscillator | 1955-02 |
| 1750-A | Sweep Drive | 1955-04 |