# Electronic Control System

Essentially, whole of the electronics world is based on three major components viz.  resistance, capacitance and inductance. Every electronic circuit whether it is simple potential divider network or a complicated circuit making a radar equipment or a television transmitter or a super computer is composed of the above stated components.

Those components, however may be present in various forms, i.e. a resistance element may be found in various circuit in the forms of thermistors or sensisters, a capacitive effect may be present in the form of a gang or a reverse biased diode or an inter electrode capacitance and similarly inductive effects may be provided by numerous types of coils, by operational amplifier circuits in IC’s and leads making connections. Thus before one goes into the details of electronics circuits and devices, the basic fundamental of these components, their application must be on one’s tips.

• Resistance: is measured in ohms, kilo ohms, mega ohms.

1 kW = 103 W                     1MW = 10 6 W

1. Wattage rating of commercially available resisters are: 1/4watt, ½ watt, 1 watt etc.
2. Sequence of colors used for color code of resistance:

Black –     0                     ;           Green – 5

Brown –   1                     ;           Blue –    6

Red –       2                     ;           Voilet –   7

Orange – 3                     ;           Grey –    8

Yellow –  4                     ;           White –  9

To memorize the color code we can remember the sentence “BB ROY Great Britain Very Good Wife”

1. For powers which are negative, use
• Golden (10 ¯ 1)
• Silver (10 ¯ 2)
• For 5% Tolerance: Golden
• For 10% Tolerance: Silver
• For 20% Tolerance: No colour
1. LDR: Is a light dependent resister.
2. VDR: Is a voltage dependent resister
3. Photoresister: Whose conductivity depend upon the amount of ight falling on it.
4. Resister: Is a linear device
5. Inductance: The component which resist a change in the current. This property of an electric component is called Inductance. It is measured Henry (H); Millihenry (m H) ; Microhenry ( lH). 1Henry = 10 3 m H =10 6 lH.

## Types of Inducters:

 RF inductors Depending upon frequency AF Inductors
 Air Inductors Depending upon core Iron core Inductors
 Single layer Depending upon the type of winding Multi layer Biflar Pie-Section

Inductance depends on the factors:

• Number of turns
• Type of core and
1. Capacitance: Is the property which resists a change in the voltage. The component which posses capacitance is known as capacitor. Capacitance is measured in picofarads (p F); nanofarads (n F) ; microfarads ( μF ) and Farads (F)

1p F=10 -6 μ F ;   1 μ F =10 –6F  ;  1n F =10 –9 F  ;

1F =10 6 μ F  ;   1F = 10 12 p F   ; 1n F =10 3 p F

## Types of capacitors:

• Paper capacitors.
• Disc capacitors
• Ceramic capacitors
• Electrolytic capacitors
• Polyester capacitors
• Air capacitors