Contents
What are the main benefits of carbon film resistors?
The big advantage of carbon composition resistors is their ability to withstand high energy pulses. When current flows through the resistor, the entire carbon composition body conducts the energy. The wirewound resistor, for example, has a much smaller volume of wire to conduct current.
Why are carbon resistors no longer the most common?
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 resistance. Due to their high price, these resistors are no longer used in most applications.
How are carbon film resistors made?
Carbon film resistors are made with a deposition process. At high temperature and under a high pressure, a ceramic carrier is held in hydrocarbon gas. The gas (methane or benzene) is cracked at a temperature of 1000 °C. The crystalline carbon is pyrolytically deposited on the ceramic substrate.
How are carbon comps and film resistors different?
Carbon Comps and Films are noisy and make amps have more hiss, pops, and sizzle. They get even nosier over time. That pan frying sound you hear in old amp is the sound of carbon resistors. Carbon films are a little quieter but not as quiet as metal film, metal oxide or wirewound resistors.
Is it safe to use metal film as a resistor?
No. They simply have less noise and do not drift in value. In short they behave more like an ideal resistor. You can find metal films in 1% tolerance so the amps with those are very consistent in sound from amp to amp. Most metal film, wirewound and metal oxide resistors are flame proof so are safe to use in power resistor applications.
Why do people use carbon as a resistor?
These same people often claim the tone in their amp is partly due to the use of carbon resistors. You can find forum posts where a person claims their amp has acquired magical properties from switching over to carbon comp resistors or claiming that they are difference between a good and bad amp. They are, of course, mostly wrong.
What kind of resistor is best for low wattage?
At one time (the 1940’s to the 1960’s) carbon composition resistors and later carbon films were the only types of resistors available for low wattage use and the cheapest. Pretty much all electronics had them inside (no TV screens did not look better because of them!).