Motorola Zener Diode Slide Rule Calculator, 1959. Donor reported that this object once belonged to her husband who worked for the Defense Mapping Agency in the 1970s through 1990s.
Companies in many countries have produced magnetic recording devices, often in association with radio production. This professional grade machine was made in the 1959 by Tandbergs Radiofabrikk of Oslo, Norway. The reel-to-reel model 2TF unit was used at the National Museum to record interviews.
Recording machines designed for dictation have used many different formats over the years. This “Time-master” unit made by Dictaphone Corporation used a 3.5-inch wide belt coated with a magnetizable material. Sold as “Dictabelt Records” in a pack of 10, these belts were stronger than regular, thin plastic recording tape.
This machine was used in the office of historian Daniel J. Boorstin when he served as director of the National Museum of History and Technology. The unit includes a loudspeaker, two different types of foot-pedal controls, and a “Twin Ear” head set.
.01: Dictaphone “Time-master” electronic dictating machine, (version 1). Includes vinyl cover, power cord (~2 meters) and green extension cord (~ 2 meters). Also includes “Dictabelt Records” (blank recording belts), one full pack of 10 belts and one pack of 9. On bottom: label 1 reads: “UL Listed under reexamination service of Underwriters Laboratories Inc.”; label 2 reads: “Rated 110 VAC 60 Cycles 45 Watts (B)”; label 3 reads in part: “Dictaphone Reg. U.S. Pat. Off. Registered Trade Mark electronic dictating machine”. Patents listed for 9 countries including US 2219030 to 2667613. Printed on front: “Dictaphone Time-master Reg. U.S. Pat. Off.”; knobs labeled: “V”, “T”, “S”. Printed on back: “Dictaphone Reg. U.S. Pat. Off. Transcribing Machine”. Printed on vinyl cover: “Dictaphone Dictating Machine Time-master Model”.
.02: Dictaphone speaker. Cord (~2 meters) to attach to transcription machine. Decals on front and back: “Dictaphone”. Painted on bottom: “51343”
.03: Dictaphone pedal control with 2 pedals and cord (~2 meters) to attach to transcription machine. Printed on bottom: “51349”, “Final OK”.
.04: Dictaphone FC-15 pedal control with single pedal and cord (~2 meters) to attach to transcription machine. Printed on bottom: “Model FC-15”. Bottom: label reads: “UL Listed under reexamination service of Underwriters Laboratories Inc.”
.05: Dictaphone FC-15 pedal control with single pedal and cord (~2 meters) to attach to transcription machine. Printed on bottom: “Model FC-15”. Bottom, one label reads: “UL Listed under reexamination service of Underwriters Laboratories Inc.”; second label reads: “Accepted by H. C.”
.06: Dictaphone “Twin Ear” head set with cord (~1.5 meters) to attach to transcription machine. Stamped on hinge: “Dictaphone Twin-Ear”.
In 1940 Marvin Camras received an engineering degree from the Armour Institute of Technology and began work at the Amour Research Foundation. The prior year he had constructed a prototype wire recorder with a new type of recording head and adapted the technique of “AC bias” for improved sound quality. AC bias involves adding a high-frequency alternating current signal to the recording that significantly lowers noise and distortion.
During World War II, Armour manufactured U.S. military wire recorders using Camras’s design. General Electric licensed the design and produced a version of the Armour recorder. After the war other companies took licenses from Armour to produce recorders. One such company was Webster-Chicago, this model 181 “Webcor” unit is one of that company’s products. Webster-Chicago’s products did well in the market and the company produced wire recorders into the early 1960s.