Weak current College】 【resistance of technical parameters and named】.

Overview: resistance is used in electronic products, electronic components, up to about 35% of the total, and some products such as TV accounted for 50% as a result of the quality of the product resistance. Common resistance have carbon film resistor metal film resistors, metal oxide film resistors, solid resistance and winding resistance.
1 resistance and resistance: conductive material to a certain extent hinder the current flows through the physical performance. In that test the sensitivity of the case, it should be noted that the test voltage must be absolute low, time to make short, avoid resistance heating caused the error. And the measurement power less than 10% of the rated power.

2 nominal resistance and tolerance: the actual and nominal values.

3 rated power: at normal atmospheric pressure (650-800mmhg) and rated temperature, long-term continuity of work and meet the performance requirements of the allowed maximum power.
4 rated voltage: from resistance and voltage of the power conversion, considering that electrical breakdown, up to a certain value, the maximum working voltage limits.

5 maximum working voltage: because of the size structure of limit the maximum continuous operating voltage.

6 temperature coefficient: in a certain range of ambient temperature, temperature 1 degree of variation of resistance.

7 insulation resistance: in the normal atmospheric pressure, resistance leader and resistance of the insulation resistance of the shell.

8 noise: from resistors of irregular voltage fluctuations, including thermal noise and current noise, thermal noise is irregular because the conductor internal electronic freedom movement, the conductor any two points in irregular changes. In nonlinear around resistance, current noise, because current noise and resistance to both ends of the work is directly proportional to voltage, so you can measure the current noise indicators uv/v

9 stability: within the specified time, the environment, the load and other factors, to maintain their initial resistance.

10 resistance load characteristics: allow the power and environmental temperature, when the ambient temperature is equal to the maximum ambient temperature, the power will be reduced to zero.

Nominal resistance and rated power series:

Nominal resistance selection consists of the following geometric series, leading to the expression represents An = (10 on k-th) n-1 (th), this is a special geometry class expression, its public opening for 10 k-th, n is the number of items, such as geometric series in 10 or less requires three values, then the k through 3, the ratio of 2.154
Press the n = 1, 2, 3, get 1, 2.154, 4.64 rounding is: 1, 2.2, 4.7
If the k through 6, the ratio of 1.468, available 1, 1.5, 2.2, 3.3, 4.7, 6.8
Resistance of nominal value series will take 6 k, respectively 12, 48, 96,192 rounding up of geometric series after, called: E6, E12, E48, E96, E192 series, use the tolerance is 20% M, 10% to 5% of K, J, 2%, 1% F G, 0.5% D.

You can see from the above, the deviation limit above resistance is overlapped, regardless of the production value of resistance, the regulation may be put to a nominal value, you can achieve zero waste production.
Resistance rating also uses a standardized rating of series of values:

0.05.1250.250.5125102550100W
Color ring mark law: black red brown 0 1 2 3 4 green yellow orange 5 blue grey purple 6 7 8 9 5% white gold silver 10%

For example: when the resistance for the fourth time, the last part will be gold or silver. So the first two digits of the digits, the first three digits of the number of powers, the fourth bit is tolerance.

When the resistance of five rings, the last ring and ring distance larger front. First three digits of the digits, the first four digits of the number of powers, the fifth bit is tolerance.

Represents a text symbol tolerance

B0.1%C0.25%D0.5%F1%G2%J5%K10%M20%N30%

Resistor designation:

Part i: the primary known as R-resistance, W potentiometer

Part II: synthesis of carbon material film T H S organic solid N J inorganic solid metal film Y metal oxide film C chemical deposition film I glass uranium film X wire wound

Part three: category 1 General 2 ordinary 3 UHF high-impedance 4 5 7 8 special precision high pressure 9 G high power adjustable D T W fine-tune many laps