Resistors
Resistors are
elements that present a difficulty in passing electricity and these elements
can have a fixed or variable resistance. Electrical resistance is measured in
Ohms (Ω).
Resistors have a
very Ar property:
The larger around
it, the smaller the electric current that passes through it.
There are many types
of resistors used, and the vast majority are too small to carry their nominal
value in their body. In this way, manufacturers use color coding or numeric codes
to inform their value.
Even smaller
resistors, which are usually of the SMD type, soldered directly to the board do
not always have their nominal value printed on the body, so it is necessary to
refer to the equipment's technical manual to find out the correct value.
Resistor Symbology
How to Read a Resistor?
When reading a
four-color band resistor, you need to be careful, as there is one color that is
usually closer to the end than the other and this will be the first one to be
considered in the reading. After identifying the color closest to the end we
can associate it with the first digit of the resistor value, the second color
is the second digit of the value and the third is the multiplier.
For example For a
resistor that has brown, black and red color bands we will have a nominal value
of 1000 Ω, as red is the multiplier. So we have the value of the digits 10
multiplied by 100Ω, resulting in 1000Ω.
This simple way we
will be able to calculate any value of resistors, including the 5-color ones,
as they are also not different from the rule, just add a digit in your
calculation verification. See the example on the next page.
Resistor Color Code Table
Below we have a
table describing the digits and multipliers that we can find according to the colors
existing in the resistors.
SMD RESISTORS (Surface Mounting Device)
As time passes, the
electronic equipment becomes smaller, and consequently the components also
follow this development. Today, within this philosophy, we can easily find SMD
resistors, where these components are small, soldered on the surface of the
board and have the nominal value in their body more in the form of a numerical
code instead of colors.
An SMD resistor with
the value equal to 2512 we can associate the first three numbers as a digit (2512)
and the number two is the multiplier (100Ω) totaling 25100Ω.
Resistive Network
A Resistive Network
is nothing more than several resistors interconnected within a single package,
being a common terminal for all. It is used in circuits that require space
saving inside the board. A Resistive Network is commonly applied to Japanese
ECUs such as Honda Civic, Toyota, Mitsubishi and others.
