Utilizing Carbon Film Resistors What exactly is carbon film resistor? To explain simply, it is a resistor created from a film of carbon deposited on a substrate. Helical cuts are generated in the film to create distinct resistance values. These kinds of carbon film resistors are engineered to serve both high voltage and high temperature applications. These resistors are done by breaking down hydrocarbon gases at extremely high temperatures and are also created in a vacuum. This brings about the development of a carbon deposit on the substrate. Heating of methane or propane gas is definitely the second step that will also complete the process. This is the process referred to as high temperature pyrolysis. Hydrogen gas will then be produced resulting from molecular condensation once the heat is applied that will create carbon. To reduce the width of the film and enhance the length, a spiral is required that can also produce increased resistance. There are lots of resistances that may be generated in addition to assortment of types and resistivity of carbon. You will be able to locate carbon film resistors which have maximum power range between 1/6 W to 2 W at Seventy degrees Celsius. Resistance in contrast, may range between roughly one ohm to Ten MegaOhm. The carbon film resistor has an operating temperature range from -50 to 140 degrees Celsius. Roughly 150 to 500 volts is the utmost voltage. Key Advantages: The main reason for utilizing the carbon film resistor is the fact that these components are remarkably inexpensive and capable to withstand high voltages and high temperatures. Not just that. There are also distinctive carbon film resistors out there which the maximum voltage that the device can work is up to 15kV. You may also get varieties with a maximum operating temperature of 350째C. These can also be found in various tolerances 2-20%. The thing that creates these particular resistive tolerances is just the cutting of helical grove in them. Regulating the pitch of the helix can make way in reaching the necessary resistance value. Normally, the thinner the carbon layer and the finer the pitch of the helix, the higher the resulting resistance value is going to be. Special alloy contact caps and tinned electrolytic copper connecting wires are pressed into the ends of the resistor body following the cutting of the helix or spiraling. Covering or coating is then the final step whereby it requires quite a few layers of lacquer, epoxy, or by using a glass film as protective shielding. This is achieved generally for electrical insulation, but also for shielding from the climate. The Disadvantages On the flip side, there are also a handful of drawbacks when you use a carbon film resistor. The first one is that they are restricted only to about 1 percent accuracy. Subsequently, they show drift with temperature and vibration. Dependent upon the resistant value, the resistors may have a TCR
(temperature coefficient of resistance) range of -250 to -1000 ppm/째C. But despite of all these, advantages still find a way to outnumber the majority of the drawbacks, particularly in certain applications. Applications These carbon film resistors can be used in a lot of products and are generally an outstanding general purpose resistor. They are the most produced axial leaded resistors at present. They are also less costly than other kinds just like metal film resistors. Some functions for carbon film resistors tend to be more exceptional than others are. They are usually utilized in x-ray equipment and a lot of other general electric equipment. Source: http://www.resistorguide.com/carbon-film-resistor/