The Pros and Cons of Making Use of Carbon Film Resistors Exactly what is a carbon film resistor? It's a resistor made of a film of carbon placed on a substrate. Moreover, helical cuts are made in the said film in order to produce diverse resistance values. Carbon film resistors are designed for both high voltage and high temperature purposes. Simply by breaking down hydrocarbon gases at extremely high temperatures; this resistor can be made. In addition, they are created in a vacuum. Out of this process, a formation of carbon deposit on a substrate transpires. The process is completed by heating methane or propane gas. This technique is known as high temperature pyrolysis. Hydrogen gas is then produced due to molecular condensation when the heat is applied that will bring about the end result: carbon. Greater resistance is generated with the use of a spiral which will reduce the width of the film and at once, expand the length. There are several resistances which can be created together with assortment of types and resistivity of carbon. Carbon film resistors possess a maximum power range between 1/8 W to 2 W at 75 degrees Celsius. And the resistance can vary from somewhere around 1 ohm to 10M Ohm. The operating temperature of this carbon film resistor varies from -45 to 150 degrees Celsius. With regards to voltage range, these resistors vary from 150 - 400 volts maximum.
The Pros The greatest thing about this carbon film resistor is that these elements are very affordable and at the same time, has the capacity to endure high voltages and high temperatures. Special carbon film resistors really exist, of which the highest voltage that the device can function is up to 15kV. You may also get types having a maximum operating temperature of 350째C. They can even be found in distinct tolerances of 5 to 20 %. These variety in tolerances are made from cutting a helical grove. The required resistance value is obtained by regulating the pitch of the helix. Normally, the thinner the carbon layer and the finer the pitch of the helix, the higher the resulting resistance value will be. Distinctive alloy contact caps and tinned electrolytic copper connecting wires are pressed to the ends of the resistor body following the cutting of the helix or spiraling. Covering or coating is then the very last step where in it involves quite a few layers of lacquer, epoxy, or by using a glass film as protective shielding. This coating is conducted mostly for electrical insulation and as well as shielding from the climate.
The Disadvantages Carbon film resistor definitely has many positive aspects but of course, it also has a handful of disadvantages. To begin with, they are confined to about 1 % accuracy. Also, they exhibit drift relating to temperature and climate. Depending on the resistant value, the resistors can have a TCR (temperature coefficient of resistance) range of -250 to -1000 ppm/°C. Obviously, advantages still outweighs the drawbacks especially when considering some distinct applications.
Figuring out its Uses: These carbon film resistors can be employed in a lot of products and they are generally a great general purpose resistor. Actually, they are the most manufactured axial leaded resistors at the moment. One of the major advantages is it’s affordability in comparison to metal film resistors. When compared with other types, the purposes of carbon film resistors are unquestionably more ideal. Useful applications of these resistors can be found in gas discharge lamps, test equipment, electrical appliances, and high voltage power supplies.