John D. Harnden Jr.

Electrical Engineer, developer of power systems and electronics

John D. Harnden Jr. worked at the General Electric Research Lab and developed many technologies. He led breakthroughs in the semiconductor field, electric lighting, power conditioning and more. He has a wide knowledge and respect for the legacy of engineering and founded the Edison Tech Center (Edison Exploratorium) in 2001. Mr. Harnden has a unique understanding of physics, materials and electromagnetic forces combined with a love of tinkering and design. Engineering has been a passionate pursuit of John's for many years and it is embodied in the non-profit he founded. See more about Edison Tech Center here.

The Metal Oxide Varistor (Surge Protector)

John worked with William G.  Morris and Francois Martzloff working on the Tyristor and Zener Diode and eventually this led to the team developing the metal oxide varistor (MOV). The GEMOV surge suppressor was perfected in 1973 and first sold in 1976. This revolutionized power conditioning at a time when computers and semiconductors were getting damaged by the uncontrolled variable voltage levels in the grid. The MOV is used in all kinds of electronics today and is a vital form of power conditioning, in other words it controls and changes electricity to work at precise parameters needed for a given device.

See this paper which includes the story of this invention:

History of Arresters on Power Systems 1965-Present by Jonathan J. Woodworth.

Below is a video with Bill Morris talking about how the MOV works:

Other Work

John Harnden developed switches and other power control devices which improved a myriad of technologies from home appliances to mega machines at steel mills. In 1968 and 1971 he developed a static electronic photoflash assembly and a disposable flashbulb lamp with William Kornrumpf.  John also developed precise timing devices using semiconductors which allowed the flash to go off at precisely the same moment as a high-speed shutter. His work on semiconductor switches also was applied to electric signs.

Other work includes:
-A method of winding circular electromagnets (like toroidal transformers) using bobbins (1975)
-High frequency power inverters used in appliances and electronics (1976)
-Cooling systems for semiconductor electronics (1977)
-Electrical device high temperature indicator (1980)
-Low cost digital volt/ampere with LCD for consumer use (1981)
-Diode assisted relay contactor (1981)
-Magnetoelastic force/pressure sensor (1983)
-System to measure current through a capacitor (1983)
-LCD hook-on digital ammeter (1984)
-Electric starting circuits for AC motors (1987)
-Piezoceramic relays developed by John and William Kornrumpf were used to make better refrigerators (1989)
-Various devices and types of piezoelectric switches (1984-1989)

Piezoelectric Switches

Mr. Harnden also worked with William Kornrumpf, James Kohl and Michael Adler on piezoelectric switches to replace electromechanical and solid state switches in the telephone industry. The piezoelectric switches were better in that they were more robust than solid state (silicon), and faster than electromechanical switches. The piezoelectral switch could be tuned to allow precise frequencies through and filter out other unwanted frequencies.  The new switches were very small and could be easily deployed in the field. Older switching required larger apparatus and infrastructure to protect it from weather.

John's team worked on many types of piezoelectric switches and rushed to design useful applications of the switch to improve all sorts of devices.

Induction Cooking Appliance

Mr. Harnden improved the induction cooking appliance by developing a more 'smart' appliance which could more precisely control heating as well as provide controls for safety. He worked on many parts of this device. Since 1971 the induction cooktop has gotten very complex. See our video below of how it works:


"Power Semiconductor Applications", edited by John D. Harnden, Jr. [and] Forest B.Golden. 1972
Mr. Harnden produced many papers for the IEEE. See the IEEE database to do further research

Related Pages:

Lightning and Surge Arrestors

Semiconductor Electronics


Control and Systems Engineering

Meters and Voltage Regulators

More Stuff

Edison Tech Center
General Electric

History of Arresters on Power Systems 1965-Present by Jonathan J. Woodworth
John Harnden Jr.
William P. Kornrumpf
Edwin Reilly Jr.
The General Electric Story. by Bernard Gorowitz. 1999

For use of Edison Tech Center images and videos see our licensing agreement.