There are two types of parametric representations of resistors

Colored ring method and number method.

k (thousand ohms), m (megaohms), their conversion relationship is:

1t = 1000g 1g = 1000m 1m = 1000k 1k = 1000 (i.e. 1,000 advance rate).

The resistance value standard method of resistor usually has the color ring method and the number method. The color ring method is more common in general resistors. Since the resistance in the mobile phone circuit is generally relatively small, it is rarely marked with a resistance value, and even if there is, the digital method is generally used, namely:

10 1 - represents the resistance of 100; 10 2 – represents the resistance of 1k; 10 3 – represents a resistance of 10k; 10 4 – 100k resistance; 10 6 – represents a resistance of 10m; 10 7 – indicates a resistance of 100m.

If a resistor is superscripted 22*10 3, then this resistor is 22k.

Numeric method uses three digits to represent the nominal value of an element. From left to right, the first two digits represent significant digits and the third digit represents 10n (n=0 8). When n=9 is a special case, it means 10 (-1).

The 103 of the plastic resistor means 10*10 3=10k. Chip resistors are mostly marked digitally, such as 512. The digital mark 479 on the capacitor is 47*10 (-1)=.

A resistor with a flag of 0 or 000 indicates that it is a jumper with a resistance value of 0. When digitally marked, the unit of resistance is ohm, the unit of capacitance is pf, and the inductance is generally not digitally marked.

The parameters of the resistor are generally expressed in terms of resistance value and accuracy. The magnitude of the resistance is expressed mathematically and in two ways.

The main parameters of the resistor are the nominal resistance value (referred to as the resistance value), the rated power and the allowable deviation;

1. Nominal resistance: The nominal resistance usually refers to the resistance value marked on the resistor. The basic unit of resistance value is ohmic (ohm for short)."ω"Denote.

In practical applications, kiloohms (k) and megaohms (m) are also commonly used to express them. The conversion relationship between megaohms (m), kiloohms (k) and ohms ( ) is: 1m = 1000k 1k = 1000 ;

2. Rated power: Rated power refers to the maximum power grip (i.e., the highest voltage and maximum current and product) that the resistor can withstand under specific conditions (under a certain atmospheric pressure and at the temperature specified in the product standard) when working for a long time in an AC or DC circuit. The rated power value of the resistor also has a nominal value, which is generally divided into 1 8W, 1 4W, 1 2W, 1W, 2W, 3W, 4W, 5W, 10W, etc.;

3. Allowable deviation: The actual resistance of a resistor cannot be absolutely equal to the nominal resistance value, and there will be a certain deviation between the two, and we call the allowable range of the deviation as the allowable deviation of the resistor. The resistor with a small allowable deviation will have higher resistance accuracy and better stability, but its production cost is relatively high and expensive.

In general, the allowable deviation of ordinary resistors is 5%, 10%, 20%, while the allowable deviation of high-precision resistors is 1%.

1. Definition: r u i. (U for voltage, I for current).

2. Definition formula: r l s. ( Indicates the resistivity of the resistor.

It is determined by its own properties, L represents the length of the resistance, and S represents the cross-sectional area of the resistance).

3. Resistance series: r r1 r2 r3 ...rn。（r1...rn represents n resistors, and the value of the resistance is determined by its own properties).

4. Resistance parallel: 1 r 1 r1 1 r2 1 r3 ...1／rn。（r1...rn represents n resistors, and the value of the resistance is determined by its own properties).

5. With electric power.

The resistance of a conductor to an electric current is called the resistance of the conductor. Resistance (usually denoted by "R") is a physical nucleus that represents the magnitude of a conductor's resistance to an electric current in physics. The greater the resistance of a conductor, the greater the resistance of the conductor to the current.

Different conductors, the resistance is generally different, and resistance is a property of the conductor itself. The resistance of a conductor is usually represented by the letter r, and the unit of resistance is ohm, referred to as ohm, and the symbol is .

The main parameters of the resistor are nominal resistance, rated power, maximum working voltage, allowable deviation, and temperature coefficient.

1. Nominal resistance.

In order to facilitate the production and use, the national standard stipulates a series of resistance as the standard of the product, that is, the nominal resistance series.

The nominal resistance is the resistance value marked on the surface of the resistor body in ohms (or 25 degrees Celsius for thermistors).

2. Rated power.

Rated power refers to the maximum power allowed by the resistor in a DC or AC circuit when the temperature specified in the product standard (-55 125 degrees Celsius) and humidity is not circulated, and the long-term load is continuous without damage or basically does not change the performance.

3. Maximum working voltage.

It is the maximum allowable continuous working voltage, and the maximum working voltage is lower when working at low air pressure.

The maximum working voltage is the working voltage limit specified by the resistor, the maximum current density of the potentiometer, the breakdown of the resistor and its structure.

4. Allowable deviation.

The allowable deviation of a resistor refers to the maximum allowable deviation of the actual resistance of the resistor from the imaginary or nominal resistance value, which marks the resistance accuracy of the resistor.

In the process of resistor production, due to the consideration of production cost and technical factors, it is impossible to manufacture a resistor that is completely consistent with the nominal resistance value, and there are inevitably some deviations, so a permissible deviation parameter is specified.

5. Temperature coefficient.

The relative change of the resistance value caused by every 1 degree Celsius change in temperature is a positive temperature coefficient and a negative temperature coefficient when the resistance increases with the increase of temperature. The smaller the temperature coefficient, the better the stability of the resistor. <>