The Collaborative International Dictionary
barretter \bar"ret*ter\, n. [OF. bareter to exchange. Cf. Barter.] 1. (Electronics) a resistor inserted into a circuit to compensate for changes (such as those arising from temperature fluctuations); a thermal cymoscope.
Syn: ballast resistor.
Note: The original form consisted of an extremely fine platinum wire loop attached to terminals and inclosed in a small glass or silver bulb. It operates by increased resistance when subjected to the influence of an electric current. In a later variety, called the
liquid barretter, wire is replace by a column of liquid in a very fine capillary tube. A recent version has a resistor composed of an iron wire in a glass bulb containing hydrogen, with the temperature variation of resistance such that the current passing through it remains constant over a wide range of applied voltages.