HOW TO CALCULATE RESISTOR & CERAMIC CAPACITOR VALUE.

You all must have had a problem while make your projects and searching old pieces of circuits for a particular resistor or a capacitor.

Well , using a multimeter is a good option but  it may not be available to most of us, and using it is a bit complicated and I will be posting it in  my next instructable on it.

Presently, I will tell you the criterion for calculating the resistance and capacitance.(Only in ceramic capacitors as it is mentioned on electrolytic capacitors)

I was making a school project and I needed some resistors and capacitors, as the local electronics shop is about 20km from my house saw I started to look in the old circuit boards I have.

As I didn't have a multimeter so I tried to understand the logic behind the codes.

Which I will be telling you.

First, of all I would Like to start off with a few basics.
For those of you who don't know what is a resistor, it is device that resists the flow of current.

The colour code is just, the resistance in the forms of  coloured strips.
The colours include-
 
1. BLACK
2. BROWN
3. RED
4. ORANGE
5. YELLOW
6  GREEN
7 .BLUE 
8. VIOLET
9. GREY
10.WHITE

Now, the first two strips of the resistor represent the digit and the third is the multipier band .
And the fourth band gives the tolerance.

The image is from  --http://www.doctronics.co.uk/resistor.htm

First,  of all I would like to give you a table so that you can calculate the resistance and tolerance.
                                                                                                                                            RESISTANCE
Now, if the first strip is brown in colour then it indicates that the fist number is 1.                1
Again, if the second strip is black then the second digit is 0.                                                10
The third strip is orange,as orange is third in the table,there will be 3 zeroes.                     10 X 1000
                                                                                  TOTAL RESISTANCE           10,000 Ohms
                                                                                                                                         

                                                                                                                                        RESISTANCE

Example, like in the picture           FIRST BAND= YELLOW                                            5
                                                   SECOND BAND= VIOLET                                            57
                                                        THIRD BAND=  RED                                                57x100
      
                                                 TOTAL RESISTANCE                                                    57,000 Ohm
Now comes the tolerance. well it is the variation inresistance.

If it is +5% then the resistance can be 5% more.

EXAMPLE- Like if it is golden in the picture the resistance  can be   _+5% of the resistance.
                                                                                                                                     57000 X 5/100
                                                                                                                                  = 2850 ohm
The resistance hence can be 57,000 +5%= 59,850 Ohm
                                               57,000-5%  = 54150 Ohm


The images are from --http://www.doctronics.co.uk/resistor.htm



                                                                       

In a five band resistor there are 5 bands instead of four.

Here are a few FAQ'S often asked about resistors-
Q1) What is a resistor?

Ans)Resistors are small electronic devices that resist the flow of electrical current. A resistor obeys Ohm's Law, which states that the voltage (or potential) across a resistor is proportional to the current flow through the resistor. In formula form, V=IR, where V is the voltage across the resistor, R is the value of the resistor in ohms, and I is the current flow through the resistor in amperes (amps).

Q2)What are the types of resistor?

Ans) There are basically five types of resistor-
         a. Fixed value resistor
         b. Variable resistor
         c. Potentiometer (adjustable resistor)
         d. Thermistor (temperature variable resistor)
         e. Photo resistor

Q3)Which side of the resistor do I read from?

Ans)The Gold or Silver band is always set to the right, then you read from left to right. Sometimes there will be no tolerance band -- Simply find the side that has a band closest to a lead and make that the first band.

Q4) Sometimes the colors are hard to make out. How do I make certain what the value of the resistor really is?

Ans)Occasionally the colors are jumbled or burnt off. The only way to read it then is with a multi-meter across the leads

Q5) How do I remember this sequence of colors?

Ans)Remember the color codes with this sentence:
Big                 - BLACK
Brown            - BROWN
Rabbits          - RED
Often             - ORANGE
Yield              - YELLOW
Great             - GREEN
Big                 - BLUE
Vocal             - VIOLET
Groans          - GREY       
When            - WHITE
Gingerly        - GOLD
Slapped.       - SILVER

The first two digits of a ceramic ceramic capacitor tells us the capacitance in uF and the next digit tells us the negative power.

Like, if it says 103 then it means it is 10 uF X 10 ^-3.

Therefore, 0.01uF.

Like in the picture the code says 154. So, it means 15 uF X  10^-4     =   0.0015 uF .

I have also uploaded a conversion table so that you can convert the  units from one to another.


The image for the ceramic capacitor is from-      electro-tech-online.com
The conversion table is from -  mechatrotutor.blogspot.com