Bendix type TT-20-A “Chronotron” tube
name: label: maker
content: Bendix
notes: label: Description (Brief)
content: A 7-pin glass base with tipped T-shaped envelope. Miniature tube. Stamped: “1204055-1 / Chronotron / TT-20A / Made in U.S.A. / Bendix”. Donor’s card reads: “Chronotron made by the Red Bank Division of the Bendix Corporation, Eatontown, NJ. Designed for use in control circuits to provide a time delay in a manner similar to an integrating device. A temperature-resistance device with two heaters and secondaries mounted in a miniature vacuum tube. The secondaries are resistance windings used in a balanced bridge circuit. A variation in one heater current changes the temperature of the corresponding secondary resistance winding. A temperature to change will cause the secondary wire, which has a positive temperature coefficient of resistivity to unbalance the secondary bridge, giving rise to an output voltage. After a heater is energized the rate of increase in output voltage is determined by the time constant of the tube, which is the time required for the output voltage to reach 63% of its maximum value. The TT-20-A used in a static bridge circuit has a time constant of 18 seconds.”
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from Paul G. Watson
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.325303
label: catalog number
content: 325303
label: accession number
content: 252994
objectType: label: Object Name
content: Electronic Control Tube
label: Object Name
content: control tube
label: Object Name
content: electron tube
label: Other Terms
content: Electronic Control Tube; Electron Tubes
physicalDescription: label: Measurements
content: overall: 2 1/2 in x 3/4 in; 6.35 cm x 1.905 cm