https://peertube.dngr.us/videos/watch/f16c8540-eeab-43de-a65e-d7672a68ac4d Join this channel to get access to perks: https://www.youtube.com/channel/UCddem5RlB3bQe99wyY49g0g/join Want to learn more about Periscope Film and get access to exclusive swag? Join us on Patreon. Visit https://www.patreon.com/PeriscopeFilm Visit our website www.PeriscopeFilm.com Part 2: https://youtu.be/aolJ7-B_cOw "Telephone Relays U and Y Type" (Part 1) is a Bell System telephone educational film produced by Audio Productions in 1951. The live action and animated film provides an overview of the importance and development of relays in the Bell System. It covers their historical background, various types, and applications in telephone systems. It also details the manufacturing process and continuous improvements made by Bell Laboratories to enhance relay reliability and performance. 0:51 - 1:01: Introduction to relays in the Bell System, mentioning there are over 150 million relays. A real relay is shown, and then an animated character representing a relay. At 1:04 a technician works on crossbar equipment in a Bell office. 1:01 - 1:19: Explanation of the number of relays per crossbar equipment and the cost of the equipment. 1:19 - 1:40: Description of where relays are used, including switchboards and private branch exchanges. At 1:26, operators are shown at switchboards. 1:40 - 2:03: A woman makes a phone call. Importance of relays in providing fast and accurate telephone service. 2:03 - 2:27: Historical background of relays, mentioning the first widely used relay before 1900. 2:27 - 3:08: Overview of different types of relays used in various telephone systems. 3:08 - 4:01: Development of the flat type relay by Bell Laboratories for mass production. 4:01 - 4:39: Introduction of U and Y type relays and their advantages. 4:39 - 5:48: Detailed description of the manufacturing process of relay parts. 5:48 - 6:09: Explanation of the annealing process to obtain required magnetic characteristics. 6:09 - 7:44: Further manufacturing steps, including electroplating and assembly of parts. 7:44 - 9:00: Coil winding process and final assembly of the relay. 9:00 - 10:05: Final adjustments and inspections to ensure relay quality. 10:05 - 11:01: Comparison of U and R relays' magnetic circuits and their improvements. 11:01 - 12:00: Introduction of bifurcated contact springs to reduce circuit troubles. 12:00 - 13:14: Importance of cleanliness and proper contact alignment in relay operation. 13:14 - 14:24: Use of high-speed photography to analyze relay operations. 14:24 - 16:40: Examination of armature bounce and spring vibration using high-speed photography. 16:40 - 17:04: Development of Bell System practices for adjusting relays properly. 17:04 - 18:39: Continuous improvements and testing at Bell Laboratories to enhance relay reliability. Motion picture films don't last forever; many have already been lost or destroyed. For almost two decades, we've worked to collect, scan and preserve the world as it was captured on 35mm, 16mm and 8mm movies -- including home movies, industrial films, and other non-fiction. If you have endangered films you'd like to have scanned, or wish to donate celluloid to Periscope Film so that we can share them with the world, we'd love to hear from you. Contact us via the weblink below. This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD, 2k and 4k. For more information visit http://www.PeriscopeFilm.com Source: https://www.youtube.com/watch?v=JGKl3R2bMMw Mirrored from Periscope Film (https://www.youtube.com/@PeriscopeFilm) Thu, 11 Jun 2026 06:46:59 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://peertube.dngr.us https://peertube.dngr.us/lazy-static/avatars/41a6fee9-7f57-42d0-a5fc-5db4f1af2e31.png https://peertube.dngr.us/videos/watch/f16c8540-eeab-43de-a65e-d7672a68ac4d All rights reserved, unless otherwise specified in the terms specified at https://peertube.dngr.us/about and potential licenses granted by each content's rightholder.