US PATENT SUBCLASS 219 / 504
.~.~.~ Comprising variable resistance means

Current as of: June, 1999
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219 /   HD   ELECTRIC HEATING

200  DF  HEATING DEVICES {14}
482  DF  .~ With power supply and voltage or current regulation or current control means {4}
490  DF  .~.~ Automatic regulating or control means {11}
504.~.~.~ Comprising variable resistance means {1}
505  DF  .~.~.~.~> Comprising nonlinear or negative temperature coefficient resistance means

DEFINITION

Classification: 219/504

(under subclass 490) Subject matter wherein the automatic regulating or control means includes a resistance device, or devices, whose resistance value or characteristics change or are changed in some way with a change in the condition of the heater or its environment.

SEE OR SEARCH THIS CLASS, SUBCLASS:

483+, for heaters wherein the current or voltage is controlled by controlling or regulating plural distinct resistance heating elements.

SEE OR SEARCH CLASS

338, Electrical Resistors,

13+, for resistors, per se, whose resistive value is responsive to a condition.