triode model
Date: 1928
Inventory Number: 1998-1-1534
Classification: Vacuum Tube
Subject:
Maker: Cruft Laboratory, Harvard University (founded 1914)
Cultural Region:
Place of Origin:
Dimensions:
45.6 x 19 x 19 cm (17 15/16 x 7 1/2 x 7 1/2 in.)
Description:
A large model of a simple triode amplifier. The wooden base has four pins, and above it is a plaster column (this would be glass in a real one) from which emerge a cathode composed of two thin filaments. The cathode is surrounded by a simple grid of thin wires coiled between two straight parallel metallic wires. On one side of the cathode and grid is the anode plate which is a metallic rectangle held vertically by two metallic wires. Made in the Cruft Laboratoy in 1928.
Signedunsigned
Inscribedon object: Scale model 201A 5":1
FunctionThis is a model to teach the basic functioning of a triode amplifier, magnified about five times. One can see in it clearly how electrons produced at the cathode filaments could be prevented from reaching the anode plate by the grid if it is held at a voltage more negative than the cathode. This is what allows vacuum tube amplifiers to work, as the amount of electrons reaching the anode is proportional to the voltage in the grid, so if one connects the grid to a weak signal, the current that flows from cathode to anode reproduces this signal on a larger scale.
ProvenanceCruft Laboratory, Harvard University.