Editing Resistor (section)

===Carbon composition===
[[File:Résistances anciennes annees 50.jpg|thumb|Old style "dog bone" resistors with "body, tip, dot" color code marking]]
[[File:Old Radio Resistors.jpg|thumb|Three carbon composition resistors in a 1960s [[Vacuum tube|valve]] (vacuum tube) radio]]
Carbon composition resistors (CCR) consist of a solid cylindrical resistive element with embedded wire leads or metal end caps to which the lead wires are attached. The body of the resistor is protected with paint or plastic. Early 20th-century carbon composition resistors had uninsulated bodies; the lead wires were wrapped around the ends of the resistance element rod and soldered. The completed resistor was painted for [[Electronic color code#Resistors|color-coding]] of its value.

The resistive element in carbon composition resistors is made from a mixture of finely powdered carbon and an insulating material, usually ceramic. A resin holds the mixture together. The resistance is determined by the ratio of the fill material (the powdered ceramic) to the carbon.  Higher concentrations of carbon, which is a good conductor, result in lower resistances. Carbon composition resistors were commonly used in the 1960s and earlier, but are not popular for general use now as other types have better specifications, such as tolerance, voltage dependence, and stress. Carbon composition resistors change value when stressed with over-voltages. Moreover, if internal moisture content, such as from exposure for some length of time to a humid environment, is significant, soldering heat creates a non-reversible change in resistance value. Carbon composition resistors have poor stability with time and were consequently factory sorted to, at best, only 5% tolerance.<ref>Harter, James H. and Lin, Paul Y. (1982) ''Essentials of electric circuits''. Reston Publishing Company. pp. 96–97. {{ISBN|0-8359-1767-3}}.</ref> These resistors are non-inductive, which provides benefits when used in voltage pulse reduction and surge protection applications.<ref name="HVRInternSR">HVR International (ed.). [http://www.hvrint.com/SRSeries.pdf "SR Series: Surge Resistors for PCB Mounting"]. (PDF; 252 kB), 26 May 2005, retrieved 24 January 2017.</ref> Carbon composition resistors have higher capability to withstand overload relative to the component's size.<ref name=Vishay08>Beyschlag, Vishay (2008). [https://www.vishay.com/docs/28771/basics.pdf "Basics of Linear Fixed Resistors Application Note"], Document Number 28771.</ref>

Carbon composition resistors are still available, but relatively expensive. Values ranged from fractions of an ohm to 22 megohms. Due to their high price, these resistors are no longer used in most applications. However, they are used in power supplies and welding controls.<ref name=Vishay08/> They are also in demand for repair of vintage electronic equipment where authenticity is a factor.