Mackontrol type A filament protector
date: label: date made
content: ca 1925
notes: label: Description (Brief)
content: A vacuum tube filament protector in original box with instruction sheet. Marked: Unit: "Pat. Pend."; Box: "Mackontrol / Mack Co. / Philadelphia". Specimen is tubular shaped glass with metal ends. Flattened ends and Fahenstock clip. Central section of glass with internal wire on a glass wafer. When inserted in series with the B battery, unit prevents accidental impressment of plate voltage across the filament by offering a high resistance to battery current in the short circuit. Reference: two instruction leaflets in box.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from Franklin Wingard
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.322019
label: catalog number
content: 322019
label: accession number
content: 241556
objectType: label: Object Name
content: vacuum tube accessory
label: Object Name
content: voltage control
physicalDescription: label: Measurements
content: box: 2 1/8 in x 6 1/4 in x 2 1/2 in; 5.3975 cm x 15.875 cm x 6.35 cm
label: Measurements
content: control: 4 1/4 in x 1 1/8 in x 13/16 in; 10.795 cm x 2.8575 cm x 2.06375 cm