Carbon film resistors are a hard and fast kind sort resistor. They’re constructed out of a ceramic provider with a skinny pure carbon film round it, which features as resistive materials.
CARBON FILM RESISTOR ADVANTAGES AND DRAWBACKS
Carbon film resistors are a big enchancment on carbon composition. Nonetheless, compared to steel movie and steel oxide film, the commercially out there vary steadily decreases. Metallic and oxide film usually are not costlier to provide, and have total higher properties.
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CARBON FILM RESISTOR APPLICATIONS
Typical use for carbon film resistors is in excessive voltage and temperature functions. Working temperatures are as much as 15kV with a nominal temperature of 350°C. Examples are excessive voltage energy provides, radar, x-rays, and laser.
Carbon film resistors are made with a deposition course of. At excessive temperature and beneath a excessive stress, a ceramic provider is held in hydrocarbon gasoline. The gasoline (methane or benzene) is cracked at a temperature of 1000°C. The crystalline carbon is pyrolytically deposited on the ceramic substrate. Due to the exact distribution of the pure graphite with out binding, these carbon resistors have a low noise.
The specified resistance worth could be obtained by choosing the proper layer thickness, and by slicing a spiral form within the carbon layer. The helical reduce within the movie will increase the size of the present path. By reducing the pitch of the helix, the size of the resistive path will increase, and there with the resistance worth will increase. Moreover, by advantageous tuning the slicing of the spiral the resistor can have the next accuracy of resistance worth.
Typical tolerance values for carbon film resistors are 2, 5, 10, and 20%. Due to the usage of pure carbon, the carbon film resistor has the next adverse temperature coefficient than carbon composition. The resistive temperature coefficient lies between 2.5×10^-4 Ω/°C and -8×10^-4 Ω/°C. Additionally, such a resistor is protected towards chemical influences with a silicone coating.
This kind of resistor is extensively utilized in electronics. Due to this fact it is very important word that the small resistors have a capability of roughly 0.5 pF. Self-induction is round 0.01 μH for uncut resistors and as much as a number of μH for spiral reduce resistors. These resistors can be found in values between 1Ω – 10’000 MΩ and have an influence ranking of 1/16, ⅛, ¼, ½, 1, or 2 watts.
metal film resistor
carbon film resistor vs metal film