(a)
Carbon Composition Resistors: Carbon composition resistor is a combination
of carbon particles and a binding resin with different proportions for
providing desired resistance. Attached to the ends of the resistive element are
metal caps which have axial leads of tinned copper wire for soldering the
resistor to the circuit. The resistor is enclosed in a plastic case to prevent
the entry of moisture and other harmful elements from outside. Billions of
carbon composition resistors are used in the electronic industry every year.
They are available in power ratings of 1/8, ¼, ½, 1 and 2W, in voltage ratings
of 250, 350 and 500V. They have low failure rates when properly used.
Carbon Composition Resistors: Carbon composition resistor is a combination
of carbon particles and a binding resin with different proportions for
providing desired resistance. Attached to the ends of the resistive element are
metal caps which have axial leads of tinned copper wire for soldering the
resistor to the circuit. The resistor is enclosed in a plastic case to prevent
the entry of moisture and other harmful elements from outside. Billions of
carbon composition resistors are used in the electronic industry every year.
They are available in power ratings of 1/8, ¼, ½, 1 and 2W, in voltage ratings
of 250, 350 and 500V. They have low failure rates when properly used.
Such resistors have a tendency to produce
electric noise due to the current passing from one carbon particle to another.
This noise appears in the form of a hiss in a loudspeaker connected to a hi-fi
system and overcome very weak signals. This is why carbon composition resistors
are used where performance requirements are not demanding and where low cost is
the main consideration. Hence, they are extensively used in entertainment
electronics although better resistors are used in critical circuits.
electric noise due to the current passing from one carbon particle to another.
This noise appears in the form of a hiss in a loudspeaker connected to a hi-fi
system and overcome very weak signals. This is why carbon composition resistors
are used where performance requirements are not demanding and where low cost is
the main consideration. Hence, they are extensively used in entertainment
electronics although better resistors are used in critical circuits.
(b)
Deposited Carbon Resistors: Deposited carbon resistors consist of
ceramic rods which have a carbon film deposited in them. They are made by
placing a ceramic rod in a methane-filled flask and heating it until, by
gas-cracking process, a carbon film is deposited on them. A helix-grinding
process forms the resistive path. As compared to carbon composition resistors,
these resistors offer a major improvement in lower current noise and in closer
tolerance.
Deposited Carbon Resistors: Deposited carbon resistors consist of
ceramic rods which have a carbon film deposited in them. They are made by
placing a ceramic rod in a methane-filled flask and heating it until, by
gas-cracking process, a carbon film is deposited on them. A helix-grinding
process forms the resistive path. As compared to carbon composition resistors,
these resistors offer a major improvement in lower current noise and in closer
tolerance.
(c)
High Voltage Ink Film Resistors: These
resistors are being replaced by metal film and metal glaze resistors. These
resistors consist of a ceramic base on which a special resistive ink is laid
down in a helical band. These resistors are capable of withstanding high
voltages and find extensive use in cathode-ray circuit, in radar and in medical
electronics. Their resistances range from 1kΩ to 100,000MΩ with voltage range
up to 1,000kV.
High Voltage Ink Film Resistors: These
resistors are being replaced by metal film and metal glaze resistors. These
resistors consist of a ceramic base on which a special resistive ink is laid
down in a helical band. These resistors are capable of withstanding high
voltages and find extensive use in cathode-ray circuit, in radar and in medical
electronics. Their resistances range from 1kΩ to 100,000MΩ with voltage range
up to 1,000kV.
(d)
Metal Film Resistors: Metal film resistors are made by depositing
vaporized metal in vacuum on a ceramic-core rod. The resistive path is helix-ground
as in the case of deposited carbon resistors. Metal film resistors have
excellent tolerance and temperature coefficient and are extremely reliable.
Hence, they are very suitable for numerous high grade applications such as in
low-level stages of certain instruments although they are very much more costly.
Metal Film Resistors: Metal film resistors are made by depositing
vaporized metal in vacuum on a ceramic-core rod. The resistive path is helix-ground
as in the case of deposited carbon resistors. Metal film resistors have
excellent tolerance and temperature coefficient and are extremely reliable.
Hence, they are very suitable for numerous high grade applications such as in
low-level stages of certain instruments although they are very much more costly.
(e)
Metal Glaze Resistors: A metal glaze resistor consists of a metal
glass mixture which is applied as a thick film to a ceramic substrate and then
fired to form a film. The value of the resistance depends on the amount of the
metal mixture. With helix-grinding, the resistance can be made to vary from 1Ω
to many megaohms. Another category of metal glaze resistors consist of a tinned
oxide film on a glass substrate.
Metal Glaze Resistors: A metal glaze resistor consists of a metal
glass mixture which is applied as a thick film to a ceramic substrate and then
fired to form a film. The value of the resistance depends on the amount of the
metal mixture. With helix-grinding, the resistance can be made to vary from 1Ω
to many megaohms. Another category of metal glaze resistors consist of a tinned
oxide film on a glass substrate.
(f)
Wire-wound Resistors: Wire-wound resistors are different from all
other types in the sense that no film or resistive coating is used in their
construction. They consist of a ceramic-core wound with a drawn wire having
accurately-controlled characteristics. Different alloys are used for providing
different resistance ranges. These resistors have highest stability and highest
power rating. Because of their bulk, high-power ratings and high cost, they are
not suitable for low-cost or high-density, limited-space applications. The
completed wire-wound resistor is coated with an insulating material such as
baked enamel.
Wire-wound Resistors: Wire-wound resistors are different from all
other types in the sense that no film or resistive coating is used in their
construction. They consist of a ceramic-core wound with a drawn wire having
accurately-controlled characteristics. Different alloys are used for providing
different resistance ranges. These resistors have highest stability and highest
power rating. Because of their bulk, high-power ratings and high cost, they are
not suitable for low-cost or high-density, limited-space applications. The
completed wire-wound resistor is coated with an insulating material such as
baked enamel.
(g)
Cermet (Ceramic Metal) Resistors: The cermet resistors are made by firing
certain metals blended with ceramic on a ceramic substrate. The value of
resistance depends on the type of mix and its thickness. These resistors have
very accurate resistance values and show high stability even under extreme
temperatures. Usually, they are produced as small rectangles having leads for
being attached to printed circuit board (PCB).
Cermet (Ceramic Metal) Resistors: The cermet resistors are made by firing
certain metals blended with ceramic on a ceramic substrate. The value of
resistance depends on the type of mix and its thickness. These resistors have
very accurate resistance values and show high stability even under extreme
temperatures. Usually, they are produced as small rectangles having leads for
being attached to printed circuit board (PCB).