Familiar with the electronic element- Resistor

In the wake of technological development, and electronic technology has developed to the fourth generation:

◆First-generation: electron tubes(1946-1958)

◆Second generation: transistor(1959-1964)

◆Third generation: integration circuit(1965-1970)

◆Fourth generation: large scale integration(1970-)

Today I will introduce some knowledge about the resistor.

History

In 1885, C S Bradley(UK) invented Molded Carbon Composition Type

In 1987, T. E . Gambrell(UK) and A. F. Harris(UK) invented Carbon film type

1913-1919, W. F. G. Swann(UK) invented Thin metal film type

In 1925, Siemens and Halske (Germany ) invented Cracked-Carbon type

Chip resistor
Color code resistor
Varistor
Thermistor

In Switching Power Supply Circuit usually use these four kinds of type: Chip resistor, Color code resistor, Varistor, Thermistor.

– Chip resistor. They come in two flavors: package and power. Just like: 0603 1/10W 0805 1/8W 1206 1/4W 0402 1/6W 1210 1/3W. 0603, 0805, 1206 are inches units,

inches
(mil)
centimeters
(mm)
L
(mm)
T
(mm)
a
(mm)
b
(mm)
2016030.60±0.050.30±0.050.10±0.050.15±0.05
40210051.00±0.100.50±0.100.20±0.100.25±0.10
60316081.6±0.150.80±0.150.30±0.200.30±0.20
80520122.00±0.201.25±0.150.40±0.200.40±0.20
120632163.20±0.201.60±0.150.50±0.200.50±0.20
121032253.20±0.202.50±0.200.50±0.200.50±0.20
181248324.50±0.203.20±0.200.50±0.200.50±0.20
201050255.00±0.202.50±0.200.60±0.200.60±0.20
251264326.40±0.203.20±0.200.60±0.200.60±0.20

Chip resistor’s resistance value representation:

 1. Numerical representation. For example, 103, the 10 represents a decimal number, the 3 represents a number of 0.

   103 = 10000R = 10K   472 = 4700R = 4.7K   151 = 150R

Another method like R100 R010, the R represents less than 1R.

   R100 = 0.1R   R010 = 0.01R

 2. Precision chip resistor. His value is made up of numeric codes, for example, 62C 43.2K  68C 49.9K   85C 75K

Precision chip resistor

code valuecode valuecode valuecode value
01100251784931673562
02102261825032474576
03105271875132275590
04107281915234076604
05110291965334877619
06113302005435778634
07115312055536579649
08118322105637480665
09121332155738381681
10124342215839282698
11127352265940283715
12130362326041284732
13133372376142285750
14137382436243286768
15140392496344287787
16143402556445388806
17147412616546489825
18150422676647590845
19154432746748791866
20158442806849992887
21162452876951193909
22165462947052394931
23169473017153695953
24174483097254996976

Accuracy

Y10-2X10-1A100B101
C102D103E104F105
Example
24A = 174 x 10= 174 x 1 = 174R
24Y = 174 x 10-2 = 1.74R 

-Color code resistor. It contains two types: metal oxide film resistor and a carbon film resistor. Their production process is different, the metal oxide film resistor is more expensive. The most common of which are: 4 bands and 5 bands. 4 bands use 4 colors represent values, 5 bands use 5 colors represent values.

Every color represents a different number:

Brown 1  Red 2  Orange 3  Yellow 4  Green 5  Blue 6  Violet 7  Grey 7  White 9  Black 0

Multiple: Gold 0.1  Silver 0.01

Accuracy: Gold 5%   Silver 10%  Brown 1%

4 band:

The first band: the first digit of the value

The second band: the second digit of the value

The third band: 10^n

The fourth band: accuracy

5 band have a high accuracy than 4 bands:

The first band: the first digit of the value

The second band: the second digit of the value

The third band: the third digit of the value

The fourth band: 10^n

The fifth band: accuracy

– Varistor. The main function is to limit the transient voltage and absorbed surge current. In Switching Power Supply Circuit, the Varistor use for lighting protection.

Varistor parameter:

  1. Withstand voltage. In a fixed current, the value of voltage through varistor. It’s very important to choose the size of the varistor, that affects the protection effect and operation life.
  2. Capacity. Through the value of maximum current allowed.
  3. Numerical representation. For example: 07D471K

07: the diameter is 7mm, the bigger size diameter, the more capacity.

D: shape, circle.

417: voltage 470V

K: accuracy 10%

– Thermistor. It contains two types: PTC and NTC.

 PTC: the higher the temperature, the greater the resistance.

 NTC: the higher the temperature, the lower the resistance.

  Thermistor parameter, for example, 5D-11

   5: resistance value 5R

   D: shape, circle

   11: the diameter is 11mm