Magic Eye DM71 & Socket - Physics Museum - The University of Queensland, Australia Skip to main content UQ Home Contacts Study Maps News Events Library my.UQ The University of Queensland Physics Museum Homepage Site menu Home About Events Search Catalogue Director's Blog Multimedia Gallery Contact Home › Magic Eye DM71 & Socket 2302 - Magic Eye DM71 & Socket ID: 2302 Maker's Name: Mullard Where made: Holland Dimensions: 0.9 × 0.9 × 5.4 cm This is a magic eye tube/valve. It has an 8-pin base which fits an 8-pin subminiature socket. The magic eye tube (or valve) for tuning radio receivers was invented in 1932 by Allen B. DuMont. The earlier types were end-viewed (see the EM34), usually with an octal or side-contact base. Later developments featured a smaller side-viewed noval B9A based all-glass type with either a fan type display or a band display (see the EM84). The end-viewed version had a round cone-shaped fluorescent screen together with the black cap that shielded the red light from the cathode/heater assembly. This design prompted the contemporary advertisers to coin the term magic eye, a term still used. There was also a sub-miniature version with wire ends (Mullard DM70/DM71, Mazda 1M1/1M3, GEC/Marconi Y25) intended for battery operation, used in one Ever Ready AM/FM battery receiver with push-pull output, as well as a small number of AM/FM mains receivers, which lit the valve from the 6.3V heater supply via a 220 ohm resistor or from the audio output valve's cathode bias. Some reel-to-reel tape recorders also used the DM70/DM71 to indicate recording level, including a transistorized model with the valve lit from the bias-oscillator voltage. (Wikipedia) On This Site Home About Search Catalogue Director's Blog Multimedia Gallery Contact Events History of Physics at UQ The International Year of Light Tour 2014 - International Year of Crystallography Home › Magic Eye DM71 & Socket The University of Queensland, Australia Brisbane St Lucia, QLD 4072 +61 7 3365 1111 Other Campuses: UQ Gatton, UQ Herston Maps and Directions © 2021 The University of Queensland A Member of Privacy & Terms of use | Feedback ABN: 63 942 912 684 CRICOS Provider No: 00025B Quick Links For Media Emergency Contact Social Media Facebook Twitter Flickr Instagram YouTube Vimeo LinkedIn Explore Giving to UQ Faculties & Divisions UQ Jobs UQ Contacts Login EMERGENCY Ph. 3365 3333
