The CK722 was the first low-cost junction transistor available to the general public. It was a PNPgermanium small-signal unit. Developed by Norman Krim, it was introduced by Raytheon in early 1953 for $7.60 each; the price was reduced to $3.50 in late 1954 and to $0.99 in 1956. Norm Krim selected Radio Shack to sell the CK721 and CK722 through their catalog. Krim had a long-standing personal and business relationship with Radio Shack.[1] The CK722s were selected "fall out" from the Raytheon's premium-priced CK721 (which are fallouts from CK718 hearing-aid transistors).[2] Raytheon actively encouraged hobbyists with design contests and advertisements.[3][4]
CK722 transistor and package
In the 1950s and 1960s, hundreds of hobbyist electronics projects based around the CK722 transistor were published in popular books and magazines.[5][6] Raytheon also participated in expanding the role of the CK721/CK722 as a hobbyist electronics device by publishing "Transistor Applications" and "Transistor Applications – Volume 2" during the mid-1950s.
Transistor application books for CK722 by Raytheon
Size comparison and metal case colors of Raytheon hearing aid transistors on the left and the CK721 (blue) and CK722 (silver) on the right. The rejected hearing aid transistors would be inside the metal cases of the CK721 and CK722.
The original CK722 were direct fallouts from CK718 hearing-aid transistors that did not meet specifications. These fallouts were later stamped with CK721 or CK722 numbers based on gain, noise and other dynamic characteristics. Early CK722s were plastic-encapsulated and had a black body. As Raytheon improved its production of hearing-aid transistors with the introduction of the smaller CK78x series, the body of the CK721/CK722s was changed to a metal case. Raytheon, however, kept the basic body size and used a unique method by taking the smaller CK78x rejects and inserting it into the larger body and sealing it. The first metal-cased CK721/CK722s were blue, and the later ones were silver. More details of this can be found in Jack Ward's website, Semiconductor Museum or the CK722 Museum, see external link reference below.
Engineers associated with the CK722
Norman Krim – father of the transistor hobbyist market
In the late 1930s, Norm Krim, then an engineer for Raytheon, was looking into subminiature tubes for use in consumer applications such as hearing aids and pocket radios. Krim's team developed the CK501X subminiature amplifier tube that could run on penlight A type batteries or small 22.5 V B-type batteries.
Following World War II, Krim was interested in developing the first pocket vacuum tube radio. Raytheon approved, and a team headed by Krim designed a set of subminiature tubes specifically for radios (2E32, 2E36, 2E42 and 2G22). Raytheon’s acquisition of Belmont Radio proved prescient, and the result was the Belmont Boulevard in 1945. The radio did not sell well, and Raytheon took a loss. Despite this setback, Krim remained at the company and shifted his attention to the newly developed transistor.[7]
Carl David Todd – participant in the CK722 design contest
Carl Todd, a hobbyist and later engineer GE’s transistor division, placed 6th in Raytheon's CK722 design contest. His hobby work with this early transistor inspired him to pursue electrical engineering as a career. As an engineer, he helped develop the 2N107 transistor, GE's alternative to the CK722.[8]
^Ward, Jack. "Norm Krim – The Father of the CK722".
^Garner, Lou (October 1979). "Solid State: Down Nostalgia Lane". Popular Electronics. Vol. 16, no. 4. New York: Ziff-Davis. pp. 86, 87, 92.
^"$10,000 in Prizes. Enter Raytheon's Transistor Application Contest!". Popular Mechanics. Vol. 99, no. 6. Chicago: Popular Mechanics Co. June 1953. p. 219. ISSN 0032-4558. Raytheon sponsored a design contest for applications that used the CK722 transistor. The top prize was $5,000.
^"8 Transistor circuits you build with Raytheon CK722 transistors". Popular Electronics. Vol. 2, no. 4. New York: Ziff-Davis. April 1955. p. 8. CK722 advertisement.
^"How to Build Experimental Transistor Receivers". Popular Mechanics. Vol. 100, no. 4. Chicago: Popular Mechanics Co. October 1953. pp. 246–248.
^Garner, Lou (November 1957). "Transistorized Instrument Amplifier". Popular Mechanics. Vol. 108, no. 5. Chicago: Popular Mechanics Co. pp. 160–162.
^Schiffer, Michael Brian (1991). The Portable Radio in American Life. Tucson, AZ: The University of Arizona Press. pp. 161–165. ISBN0816512841.
A general summary of Norman Krim's achievements can be seen at this IEEE link In Memoriam- Norm Krim
Jack Ward's Semiconductor Museum-The CK722 transistor website and museum
Harry Goldstein's IEEE article on celebrating the transistor- Goldstein, Harry (March 2003). "The Irresistible Transistor". Spectrum. IEEE. 40 (3): 42–47. doi:10.1109/MSPEC.2003.1184435. webarchive backup:
January 08, 2023
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The CK722 was the first low cost junction transistor available to the general public It was a PNP germanium small signal unit Developed by Norman Krim it was introduced by Raytheon in early 1953 for 7 60 each the price was reduced to 3 50 in late 1954 and to 0 99 in 1956 Norm Krim selected Radio Shack to sell the CK721 and CK722 through their catalog Krim had a long standing personal and business relationship with Radio Shack 1 The CK722s were selected fall out from the Raytheon s premium priced CK721 which are fallouts from CK718 hearing aid transistors 2 Raytheon actively encouraged hobbyists with design contests and advertisements 3 4 CK722 transistor and package In the 1950s and 1960s hundreds of hobbyist electronics projects based around the CK722 transistor were published in popular books and magazines 5 6 Raytheon also participated in expanding the role of the CK721 CK722 as a hobbyist electronics device by publishing Transistor Applications and Transistor Applications Volume 2 during the mid 1950s Transistor application books for CK722 by Raytheon Size comparison and metal case colors of Raytheon hearing aid transistors on the left and the CK721 blue and CK722 silver on the right The rejected hearing aid transistors would be inside the metal cases of the CK721 and CK722 Contents 1 Construction 2 Engineers associated with the CK722 2 1 Norman Krim father of the transistor hobbyist market 2 2 Carl David Todd participant in the CK722 design contest 3 See also 4 References 5 External linksConstruction EditThe original CK722 were direct fallouts from CK718 hearing aid transistors that did not meet specifications These fallouts were later stamped with CK721 or CK722 numbers based on gain noise and other dynamic characteristics Early CK722s were plastic encapsulated and had a black body As Raytheon improved its production of hearing aid transistors with the introduction of the smaller CK78x series the body of the CK721 CK722s was changed to a metal case Raytheon however kept the basic body size and used a unique method by taking the smaller CK78x rejects and inserting it into the larger body and sealing it The first metal cased CK721 CK722s were blue and the later ones were silver More details of this can be found in Jack Ward s website Semiconductor Museum or the CK722 Museum see external link reference below Engineers associated with the CK722 EditNorman Krim father of the transistor hobbyist market Edit In the late 1930s Norm Krim then an engineer for Raytheon was looking into subminiature tubes for use in consumer applications such as hearing aids and pocket radios Krim s team developed the CK501X subminiature amplifier tube that could run on penlight A type batteries or small 22 5 V B type batteries Following World War II Krim was interested in developing the first pocket vacuum tube radio Raytheon approved and a team headed by Krim designed a set of subminiature tubes specifically for radios 2E32 2E36 2E42 and 2G22 Raytheon s acquisition of Belmont Radio proved prescient and the result was the Belmont Boulevard in 1945 The radio did not sell well and Raytheon took a loss Despite this setback Krim remained at the company and shifted his attention to the newly developed transistor 7 Carl David Todd participant in the CK722 design contest Edit Carl Todd a hobbyist and later engineer GE s transistor division placed 6th in Raytheon s CK722 design contest His hobby work with this early transistor inspired him to pursue electrical engineering as a career As an engineer he helped develop the 2N107 transistor GE s alternative to the CK722 8 See also EditAlfred Powell Morgan an author of youth oriented books on early electronicsReferences Edit Ward Jack Norm Krim The Father of the CK722 Garner Lou October 1979 Solid State Down Nostalgia Lane Popular Electronics Vol 16 no 4 New York Ziff Davis pp 86 87 92 10 000 in Prizes Enter Raytheon s Transistor Application Contest Popular Mechanics Vol 99 no 6 Chicago Popular Mechanics Co June 1953 p 219 ISSN 0032 4558 Raytheon sponsored a design contest for applications that used the CK722 transistor The top prize was 5 000 8 Transistor circuits you build with Raytheon CK722 transistors Popular Electronics Vol 2 no 4 New York Ziff Davis April 1955 p 8 CK722 advertisement How to Build Experimental Transistor Receivers Popular Mechanics Vol 100 no 4 Chicago Popular Mechanics Co October 1953 pp 246 248 Garner Lou November 1957 Transistorized Instrument Amplifier Popular Mechanics Vol 108 no 5 Chicago Popular Mechanics Co pp 160 162 Schiffer Michael Brian 1991 The Portable Radio in American Life Tucson AZ The University of Arizona Press pp 161 165 ISBN 0816512841 Jack Ward s interview with Carl Todd External links Edit Wikimedia Commons has media related to CK722 A general summary of Norman Krim s achievements can be seen at this IEEE link In Memoriam Norm Krim Jack Ward s Semiconductor Museum The CK722 transistor website and museum Harry Goldstein s IEEE article on celebrating the transistor Goldstein Harry March 2003 The Irresistible Transistor Spectrum IEEE 40 3 42 47 doi 10 1109 MSPEC 2003 1184435 webarchive backup Free version Retrieved from https en wikipedia org w index php title CK722 amp oldid 1120038905, wikipedia, wiki, book, books, library,
