Technology ki Dunya

  The bipolar junction transistor is constructed with three-doped semiconductor regions separated by two PN junctions.  The three regions are called  a.      Emitter b.      Base c.      Collector.  The two types of bipolar transistors are  (a). One type consists of two N-regions separated by a P-region (NPN),  and the other consists of two P-regions separated by an N-region (PNP).  The PN junction joining the base region and the emitter region is called the base-emitter junction.  The junction joining the base region and the collector region is called the base-collector region. A wire lead connects to each of the three regions.  These leads are labeled E, B, and C for the emitter, base, and collector, respectively. The base material is lightly doped and very narrow compared to the heavily doped emitter and collector materials.  the schematic symbols for the NPN and PNP bipolar transistors. Th...

  The Light Emitting Diodes (LED) The basic operation of the led is as follows:  When the device is forwarded biased, electron crosses the PN junction from the N-type material and recombine with holes in the P-type material. Recall that those free electrons band and at a higher energy level then holes in the valance band.  When recombination takes place, the recombining electrons release energy in the form of heat and light.  A large exposed surface area on one layer of the semiconductor material permits the photons to be emitted as visible light.  (a) illustrates this process, which is called electroluminescence. The semiconductor materials used in LEDs are gallium arsenide (GaAs), gallium arsenide phosphide (GaAs), and gallium phosphide (GaP).  Silicon and Germanium are not used because they are essentially heated producing material and are very poor at producing light. GaAs LEDs emit infrared (IR) radiation. GaAsP produces either red or yellow light, and...

  Diode Diode is a semiconductor device. Because of their unique ability to conduct current in only one direction, diode are used in rectifier circuits. Rectification is the process of converting AC to pulsating DC. Diode and its symbol       Half Wave Rectifiers When the sine wave inpu t voltage goes positive, the diode is forward-biased and conducts current to the load resistor. The current produces a voltage across the load, which has same shape as the positive half-cycle of the input voltage. When the input voltage goes negative  during the second half of its cycle, the diode is reversed- biased. There is no current, so the voltage across the load resistor is 0. The net result is that only the positive half cycles of the ac input voltage appears across the load, making the output a pulsating DC voltage. This process is called half wave-rectification ڈایڈ ایک نیم کنڈکٹر ڈیوائس ہے۔   ڈایڈڈ صرف ایک ہی سمت میں کرنٹ...

  Semiconductors Semiconductors are classed below the conductors in their ability to carry current because they have fewer free electrons than do conductors.   Semiconductors are characterized by four valence electrons in their atomic structures.   However, because of their unique characteristics, certain semiconductor materials are the basis for modern electronic devices such as the diode, transistor, and integrated circuit.   Silicon and germanium are common semiconductor materials. سیمی کنڈکٹر کو کرنٹ لے جانے کی صلاحیت میں کنڈیکٹر کے نیچے درجہ بند کیا جاتا ہے کیونکہ ان کے پاس کنڈکٹر کے مقابلے میں الیکٹران کم ہوتے ہیں۔ سیمیکمڈکٹرز کو ان کے جوہری ڈھانچے میں چار والینس الیکٹران کی خصوصیات دی جاتی ہے۔ تاہم ، ان کی انوکھی خصوصیات کی وجہ سے ، کچھ سیمیکمڈکٹر مادے جدید الیکٹرانک آلات جیسے ڈایڈڈ ، ٹرانجسٹر ، اور مربوط سرکٹ کی بنیاد ہیں۔   سیلیکون اور جرمینیم سیمیکمڈکٹر کا عام مادہ ہیں۔    

  First Ten Decimal number change  into Binary Code  پہلے دس اعشاریہ نمبر کوبائنری کوڈ میں تبدیل کریں     Decimal               =                    Binary Code             1                       =                        000 I           2                       =                         00 I0           3                      =                           00II      ...

  Binary Numbers     Introduction to binary Numbers. بائنری نمبروں کا تعارف Counting in the binary system بائنری نظام میں گنتی         The same type of positional notation is used in the binary number system as in the decimal system. Although the same positional notation system is used.     The decimal system uses powers of   10. The binary system powers of   2. As was previously explained   The decimal number of 125.   Actually means  =                    1 x 10 2 + 2 x 101 + 5 x 10 0    .   In the binary system,  The same number   = (125)  is represented as 1111101. Meaning = 1 x 2 6 + 1 x 2 5 + 1 x 2 4 + 1 x 2 3 + 1 x 2 2 + 0 x 2 1 + 1 x 2 0 . To express the value of a binary number, therefore, a n   - 1 2 n -1 + a n – 2   2 n – 2 + . . . + a 0 is represented as a n...

  There are two types of  charge  1.      Positive  charge. 2.      Negative  charge .  The electron is the smallest particle that exhibits negative electrical charge.  When an excess of electrons exists in a material, there is a net negative electrical charge.  When a deficiency of electrons exists there is a net positive electrical charge.    The charge of an electron and that of a proton are equal in magnitude. Q symbolizes electrical charge. Static electricity is the presence of a net positive or negative charge in a material.   Everyone has experienced the effects of static electricity from time to time  For example, When attempting to touch a metal surface or another person or when the clothes in a dryer cling together.   Materials with charges of opposite polarity are attracted to each other and materials with charge of the same polarity are repelled There is force acting between char...