# Analog & digital electronics , logic gates , conversion of decimal numbers and binary numbers

**Analog electronics**

**There are two types to deal with the input voltage and the output voltage in the electric circuit which are the analog electronics and the digital electronics , Analog electronics are electronics that deal with the physical quantities as it is , such that it converts them into continuous electronic signals which means it takes any values of the decimal numbers .**

**Applications**

**Microphone : Converting the sound into electric signal .****Normal video camera : Converting the image into electric signal .****Normal television :**

**At sender : The sound or the image are converted into electric signals then into electromagnetic signals .**

**At receiver : The electromagnetic signals are converted into electric signals in antenna then the receiver device converts it into sound and image .**

**Disturbance ( Electronic noise ) : Source of the disturbance is the random motion of the electrons as they are charges if they move , they cause random current , ****The disturbance affects on the analog signals where noise interfere with the analog signals which carry the information and disturb it .**

**Digital electronics**

**Digital electronics are the electronics that deal with the physical quantities after converting them into discrete code based on two values only ( 0 , 1 ) where code 0 logic low and code 1 logic high .
**

**At sender : All the connected electric signals are converted into digital signals using analog to digital converter ( ADC ) .**

**At receiver : The digital signals are converted into analog signals using digital to analog converter ( DAC ) .**

**Applications**

**Cell phone .****Digital satellite channels .****Laser CD .****Computer devices :**

**All the letters and the numbers which enter the computer are converted into binary codes , ****The image is divided into small elements ( pixels ) then it is converted into binary codes ( 1 , 0 ) , ****The calculations are processed based on binary algebra .**

**The information is stored in the temporary memory ( RAM ) or the permanent memory ( Hard disk ) in the form of magnetization in a certain direction which means ( 0 ) or magnetization in the opposite direction which means ( 1 ) .**

**Source of the disturbance is the random motion of the electrons as they are charges if they move , they cause random current , ****The information isn’t the value of the signal that noise might interfere with it and cause disturbance but the information is only code ( 1 , 0 ) and it does not matter if noise is added to it .
**

**Converting the analog number ( decimal ) into digital code ( binary number ) **

**To convert the analog number ( decimal ) into digital code ( binary number ) ,****Divide the decimal number by 2 if t****he product has a remainder put 1 in the remainder cell ,****If the product has no remainder , put 0 in the remainder cell .****Divide the product by 2 and so until the product becomes less than 1 , so we put 0 in the product cell , 1 in the remainder cell .****Write down the numbers in the remainder cell respectively inside the two brackets : ( )**_{2}.

**Example : The digital code of the analog number 19 is ( 10011 ) _{2}**

**Converting digital code ( binary number ) into analog number ( decimal )**

**To covert digital code ( binary number ) into analog number ( decimal ) ,****Write down the code ( 0 , 1 ) each number separately in the order and below each number from the right side write the binary system ( 2**^{0}, 2¹ , 2² , 2³ …… ) .**Write down the product of multiplying the code ( 0 a , 1 ) in the binary system ( ( 2**^{0}, 2¹ , 2² , 2³ …… ) .

**Add the produced numbers to obtain the required analog number .**

**Example : Find the analog number for the digital code ( 10001 ) _{2} . **

**The summation of the product = 1 × 2 ^{0} + 0 × 2¹ + 0 × 2² + 0 × 2³ + 1 × 2^{4} = 1 + 0 + 0 + 0 + 16 = 17 which is the required analog number .**

**Logic gates **

**The digital electronics is the base of many of instruments and electronic components such as logic gates , Modern applications of electronics such as computer circuits and modern communication systems depend on digital circuits called logic gates .**

**We can calculate the number of possibilities in the truth table from the relation 2 ^{n} where n is the number of input , **

**Logic gates are parts of electronic circuits of modern devices which perform logic operations on the digital signals depends on codes ( o , 1 ) , There are different types of logic gates :**

**Inversion ( NOT ) **

**Number of input and output : One input and one output .**

**Logic operation : Inverse ( The output is inverse of the input ) : ****If the input is 0 the output is 1 , ****If the input is 1 the output is 0 .**

**The equivalent electric circuit : A key in parallel in the circuit , when operating the key , the lamp lights and when closing it , the lamp does not light .**

**Coincidence ( AND )**

**Number of input and output : Two or more inputs and one output .
**

**Logic operation : Simultaneity the output is not one unless all inputs are one , ****When the two inputs are 1 and 0 the output is 0 , ****When the two inputs are 1 and 1 the output is 1 .**

**Two keys are in series in the circuit , The lamp will not light until the two keys are closed .**

**Optionality ( OR )**

**Number of input and output : Two or more inputs and one output .**

**Logic operation : Optional the output is one or more of inputs is one , ****When the two inputs are 0 , the output is 0 , ****When the two inputs are 1 and 0 the output is 1 , ****When the two inputs are 1 the output is 1 .
**

**Two keys are in parallel with each other in the circuit , The lamp will light when one key is closed or the two keys are closed .**

**Transistors types , structure ( pnp transistor & npn transistor )**

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