Introduction For Resistors

Definition Resistors
Resistors are electronic components of the two channels are designed to withstand an electric current by producing a voltage drop between the two channels in accordance with the current flowing, according to Ohm's law:

V = I x R

I = V / R

Resistors are used as part of electronic networks and electronic circuits, and is one of the most frequently used components. Resistors can be made from a variety of compounds and movies, even the wire resistance (wire made from high resistivity alloys such as nickel-chromium).

The main characteristics of the resistors is the resistance and the electrical power that can be wasted. Other characteristics include temperature coefficient, electrical sighed, and inductance.

Resistors can be integrated into hybrid circuits and printed circuit boards, integrated circuits even. The size and location of the foot depends on the design of circuits, resistors must be physically large enough so as not to overheat while wasting resources.

Units

Ohm (symbol: Ω) is the SI unit for electrical resistance, named after George Simon Ohm. Usually used the prefix miliohm, kiloohm and megaohm.


Construction RESISTOR
Carbon composition
Carbon composition resistors consist of a tubular resistive element with a wire or metal lid on both ends. Resistor body is protected with paint or plastic. Old carbon composition resistors have not isolated entities, wire wrapped around the end of the resistive element and then soldered. Resistors which have become painted with the color code of the price.

Resistive element is made from a mixture of carbon powder and insulating material (usually ceramic). Resin is used to embed the mix. Resistance is determined by the ratio of carbon powder with insulating material. Carbon composition resistors are often used before the 1970s, but now not so popular as other types of resistors have better characteristics, such as tolerance, self-reliance against stress (carbon composition resistors change resistance when subjected to more stress), and the independence of the stress / strain . In addition, if the resistor becomes damp, heat from the solder can lead to changes in resistance that can not be refunded.

However, these resistors are very reliable if never given overvoltage or overheating.
This resistor is still produced, but relatively quite expensive. Resistance ranges from several miliohm to 22 MOhm.

The composition of the carbon film
Layer of carbon film deposited on a layer of insulator substrate, and cuts made to form a spiral resistive path long and narrow. By changing the width of cut lines, coupled with a resistivity of carbon (between 9 to 40 μΩ-cm) can provide a wide resistance. Carbon film resistor power rating between 1 / 6 W to 5 W at 70 ° C. Resistance is available from 1 ohm to 10 MOhm. Resistor carbon film can work at temperatures between -55 ° C to 155 ° C. It has a maximum working voltage of 200 to 600 volt.

The composition of the metal film
The main resistive element of foil resistors is a special alloy metal foil as thick as several micrometers.
Foil resistors are resistors with precision and best stability. One of the important parameters influencing stability is the temperature coefficient of resistance (TCR). TCR of foil resistors is very low. Ultra-precision foil resistors have a TCR of 0.14ppm / ° C, tolerance ± 0005%, long-term stability 25ppm/tahun, 50ppm / 3 years, the stability of the load 0.03% / 2000 hours, heat 0.1μvolt EMF / ° C, sigh-42dB, voltage coefficient of 0.1ppm / V, 0.08μH inductance, capacitance 0.5pF.

MARKING RESISTOR
Axial Resistors typically use a color banding pattern to indicate resistance. Resistor pairs numerically ditandas-surface if large enough to be marked, usually small size resistors are now used is too small to be marked. Packaging is usually light brown, brown, blue, or green, although other colors are also possible, such as dark red or gray.

Resistors beginning of the 20th century is usually not isolated, and dipped into the paint to cover the entire body for color coding. Given a second color on one end, and a point (or ribbon) colors in the middle to give the third digit. The rule is "the body, tip, point" gives the order of two decimal digits of the resistance and the multiplier. Basically tolerance is ± 20%. Resistors with a tolerance that is more tightly using silver color (± 10%) or gold (± 5%) on the other end.

Identification of four bands
Identification of four ribbons are color coded scheme the most frequently used. It consists of four color printing ribbon surrounds the resistor body. The first two bands are two-digit price information resistance, the third band is the multiplier (number of zeros are added after the two-digit resistance) and the fourth is the tolerance of the price band of resistance. Sometimes a fifth band indicates the temperature coefficient, but this must be distinguished from a true color system that uses five three-digit resistance.

For example, green-blue-yellow-red is 56 x 104Ω = 560 kΩ ± 2%. Easier description is: The first tape, green, has a price of 5 and a second ribbon, blue, has a price of 6, and both are counted as 56. The third tape, yellow, has a price of 104, which added four zeros in the back 56, while the fourth ribbon, red, is the code for the tolerance of ± 2%, giving 560.000Ω value on the accuracy of ± 2%.