16-04-2012, 02:22 PM
Concept of Embedded systems Design
[attachment=20149]
BASIC ELECTRONICS
In order to design your devices one must know the basic concepts of Electronics. We will be going to learn some basic concepts of electronics in the following chapters.
Basic components that are used in electronics are:
1. Resistor
2. Capacitor
3. Diode
4. LED
5. Transistor
6. Power supply
7. Voltage regulators
Besides the above one must have the knowledge about the sensors & how they work & how to make your own sensors.
Basic Electronics Components
RESISTOR
Resistors offera resistance to theflow of current. Mainly resistors are classified according to their resistance values and their power ratings. Resistances range from 10 ohm to56Mohm (or more) and power ratings from 1/8W to 20W. We mostly use resistance in this range even though more power rating high value resistors are available. So when you select a resistor its value and power rating should be the deciding parameter. Normally available resistors are 1/8W, 1/4W.
There are two types of resistors - fixed and variable.
Register color coding
We can measure the resistance of a resistor. This isdone by color coding over the resistor or you can use multi-meter to measure resistance. As a beginner you should use color coding. Usually we can see that 4-band code, 5--band code and 6--band code registers are available but we mainly get resistors of 4-band code.
POTENTIOMETER(POT)
Potentiometer is a variable resistor which is usedto vary the resistance by rotating the shaft. Potentiometers are available from 100 ohm to 470Kohm(or more). Cost depends on the size of potentiometer, vary from Rs.4 onwards.
Potentiometer is used as a voltage divider.Mainly potentiometers are used to generate reference voltage for LM324.
CAPACITOR
A capacitor is used to store charge. Like resistors there is fixed as well as variable capacitor also. But we mostly use fixed capacitor in robotics;variable capacitors are mainly used in analog communication. There are capacitors with no polarity and polarity. Ceramic and Mica capacitors available are of no-polarity, but electrolytic capacitors are of polarity.
We can identify negative lead of electrolytic capacitor by checking the length of the lead, one with less length is -ve. On thebody of electrolytic capacitor -ve symbol is shown.Be careful about electrolytic capacitor because inverting polarity can make 'explosion'
Every capacitor has two factors - value of its capacitance and other the maximum voltage rating.
DIODES
Diodes are two terminal devices which conduct electricity in one direction. Current flows from anode to cathode when the diode is forward biased. In a normal forward biased diode, energy is dissipated as heat in the junction.
In robotics we use normal diodes as freewheeling diodes* or to make power supply.Mostly we us 1N4001 or 1N4007 as freewheeling diodes for motors or relays.
*Flywheel diodes are in fact clamping diodes served to provide a DC discharge path for the remnant stored energy from an inductive load such as a motor or a solenoid. In principle, this is counteracting the back emf due to Lenz's Law for any devices built on the principle of electromagnetism such as an inductor or a solenoid. In short, it is a protection mechanism.
LIGHT EMITTING DIODE(LED)
In a normal forward biased diode, energy is dissipated as heat in the junction, but in LED's energy is dissipated as visible light.
The main specification of LED are its current rating=20mA, typical cut in voltage=2V,life time=2lakh hours,max. voltage is around 4.5V. There are different color LED's depending on the semi conducting material.
LED has two leads- cathode and anode. They are identified by the length of the lead. Cathode lead is of lesser length.
[attachment=20149]
BASIC ELECTRONICS
In order to design your devices one must know the basic concepts of Electronics. We will be going to learn some basic concepts of electronics in the following chapters.
Basic components that are used in electronics are:
1. Resistor
2. Capacitor
3. Diode
4. LED
5. Transistor
6. Power supply
7. Voltage regulators
Besides the above one must have the knowledge about the sensors & how they work & how to make your own sensors.
Basic Electronics Components
RESISTOR
Resistors offera resistance to theflow of current. Mainly resistors are classified according to their resistance values and their power ratings. Resistances range from 10 ohm to56Mohm (or more) and power ratings from 1/8W to 20W. We mostly use resistance in this range even though more power rating high value resistors are available. So when you select a resistor its value and power rating should be the deciding parameter. Normally available resistors are 1/8W, 1/4W.
There are two types of resistors - fixed and variable.
Register color coding
We can measure the resistance of a resistor. This isdone by color coding over the resistor or you can use multi-meter to measure resistance. As a beginner you should use color coding. Usually we can see that 4-band code, 5--band code and 6--band code registers are available but we mainly get resistors of 4-band code.
POTENTIOMETER(POT)
Potentiometer is a variable resistor which is usedto vary the resistance by rotating the shaft. Potentiometers are available from 100 ohm to 470Kohm(or more). Cost depends on the size of potentiometer, vary from Rs.4 onwards.
Potentiometer is used as a voltage divider.Mainly potentiometers are used to generate reference voltage for LM324.
CAPACITOR
A capacitor is used to store charge. Like resistors there is fixed as well as variable capacitor also. But we mostly use fixed capacitor in robotics;variable capacitors are mainly used in analog communication. There are capacitors with no polarity and polarity. Ceramic and Mica capacitors available are of no-polarity, but electrolytic capacitors are of polarity.
We can identify negative lead of electrolytic capacitor by checking the length of the lead, one with less length is -ve. On thebody of electrolytic capacitor -ve symbol is shown.Be careful about electrolytic capacitor because inverting polarity can make 'explosion'
Every capacitor has two factors - value of its capacitance and other the maximum voltage rating.
DIODES
Diodes are two terminal devices which conduct electricity in one direction. Current flows from anode to cathode when the diode is forward biased. In a normal forward biased diode, energy is dissipated as heat in the junction.
In robotics we use normal diodes as freewheeling diodes* or to make power supply.Mostly we us 1N4001 or 1N4007 as freewheeling diodes for motors or relays.
*Flywheel diodes are in fact clamping diodes served to provide a DC discharge path for the remnant stored energy from an inductive load such as a motor or a solenoid. In principle, this is counteracting the back emf due to Lenz's Law for any devices built on the principle of electromagnetism such as an inductor or a solenoid. In short, it is a protection mechanism.
LIGHT EMITTING DIODE(LED)
In a normal forward biased diode, energy is dissipated as heat in the junction, but in LED's energy is dissipated as visible light.
The main specification of LED are its current rating=20mA, typical cut in voltage=2V,life time=2lakh hours,max. voltage is around 4.5V. There are different color LED's depending on the semi conducting material.
LED has two leads- cathode and anode. They are identified by the length of the lead. Cathode lead is of lesser length.