Tuesday, October 23, 2012

Install missing drivers to any computer in just few minutes


Sometime when you install or reinstall a windows XP, Vista or Seven you had some missing drivers such as:
Ethernet Controller
Network Controller
Multimedia Audio Controller
Audio Device on High Definition Audio Bus
Video Controller
Video Controller ( VGA Compatible)
PCI Serial Port
PCI Simple Communications Controller
PCI Device
Coprocessor
Biometric Coprocessor
Universal SerialBus (USB) Controller
System interrupt controller
Base System Device
Broadcom USH w/swipe sensor
USB device
SM Bus controller
Unknown device

To resolve this problem you need the DriverPack Solution DVD

DriverPack Solution is the most popular program that makes the job of finding and automatically installing drivers a pleasure

DriverPack Solution simplifies the process of installing missing drivers on any computer.
To download DriverPack Solution from the official site Click here 

Youtube videos are black screen on my firefox browser.


Problem: You can’t play any youtube videos on firefox browser, yesterday you had no problems viewing any youtube videos but today all the videos on youtube website appear as a black screen, you don’t have any problems with intenret explorer or google chrome.

1) Solution 1: Disable Shockwave Flash plugin in firefox and restart firefox.

2) Solution 2: Delete the history and all cockies on firefox and restart it.

3) Solution 3: If you have Adblock Disable it and restart firefox.

4) Solution 4: Disabled all the extensions and the add-on in firefox and restart it.

Repairing Power Supply COMPAQ HP PDP-124P 185W

Preferably using a low electric current in the test, less than 220 volts, It is better to have 80 volts, so as not to damage the others components of the power supply.

Repairing Power Supply COMPAQ HP PDP-124P 185W



After you opened the power supply box, start the measurement of the following pieces, they are most damaged pieces in the COMPAQ HP PDP-124P 185W power supply:
  1. Fuse 5 Am
  2. Resistor value MOV1_2_3 V10K
  3. Resistor value 1 kilo ohms (Brown. Black. Red. Gold) R9
  4. Resistor value 1 Kilo Ohm  (Brown. Black. Red. Gold) R5
  5. Resistor value 330 ohms (Orange. Orange. Black. Gold) R7
  6. Resistor value 1 ohms 1 Watt R11
  7. Integrated circuit U1 UC3845
  8. Integrated circuit U5 TOP 244P
  9. Transistor  Q1 PN 2907A
  10. Transistors MOSFET Q1 FQA9N90C
  11. Transistors Q2 B1116
  12. PHOTOCOUPLER 6 U1 U3 B337T
Replace defective components


Repairing Power Supply COMPAQ PDP-115P 120W

Preferably using a low electric current in the test, less than 220 volts, It is better to have 80 volts, so as not to damage the others components of the power supply.

Repairing Power Supply COMPAQ PDP-115P 120W


After you opened the power supply box, start the measurement of the following pieces, they are most damaged pieces in the COMPAQ PDP-115P 120W  power supply:
  1. Fuse 5 Am
  2. Resistors  1,2,3 and 4 value  V10K VDR
  3. Resistor R3 value 120 kilo ohms
  4. Integrated circuit IC1 and IC2 type: KA 358S
  5. Integrated circuit IC3 type: UCC 3581 N
Replace defective components

Friday, October 12, 2012

What is MOSFET


MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is a semiconductor device used to control and amplify current. MOSFET is four electronically active regions that are marked: gate (G), source (S), and drain (D), and the bulk terminal (B) to which the gate, drain, and source voltages are typically referenced. The rectangular gate region lies on top of the bulk separated by a thin silicon oxide dielectric with thickness. Two other important dimensions are the transistor gate length and width. The drain and source regions are embedded in the substrate but have an opposite doping to the substrate.


There are two types of MOSFET transistors, the nMOS transistor and the pMOS transistor, that differ in the polarity of carriers responsible for transistor current. The charged carriers are holes in pMOS transistors and electrons in nMOS transistors.



MOSFET Operate: A MOSFET has a gate that is insulated from the channel. A voltage that is applied to the gate will attract charge from the channel toward the gate. This charge cannot move through the gate because of the insulation. But, this “moved” charge does change the conductivity of the channel.


A simple description treats the MOSFET operate. When the gate has a high voltage, the transistor closes like a wall switch, and the drain and source terminals are electrically connected. Just as a light switch requires a certain force to activate, the transistor gate terminal needs a certain voltage level to switch and connect the drain and source terminals. This voltage is called the transistor threshold voltage Vt and is a fixed voltage for nMOS and for pMOS devices in a given fabrication process.


The most common MOSFET is the enhancement mode MOSFET. In an n-channel enhancement mode MOSFET the resistance from the source to drain is relatively high; therefore, very little current can flow. However, a positive voltage at the gate causes the channel to induce negative charges which allows more electrons to flow from the source to the drain. This means that the resistance of the channel is easily controlled by the gate.

Practical form of the MOSFET



CMOS: Complementary MOSFET

Complementary Metal Oxide Semiconductor Field Effect Transistor is a technology for constructing integrated circuits. In this circuit, two MOSFETs P-channel and N-channel are connected in series so that source of P-channel device is connected to a positive voltage supply + VDD and the source of N-channel device is connected to the ground. Gates of both the devices are connected as a common input and drain terminals of both the devices are connected together as a common output.

When the input is low on the gate, the P-channel MOSFET will be ON, the drain and source terminals are electrically connected and the N-channel MOSFET is OFF.
In other case when the input is high on the gate, the N-channel MOSFET will be ON, the drain and source terminals are electrically connected and the P-channel MOSFET is OFF.






What is Transistor


Transistor is an active electronic component composed of semiconductor material with three terminals that can function as electronic switches or as signal amplifiers.


 Modern transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Application of current in BJTs and voltage in FETs between the input and common terminals increases the conductivity between the common and output terminals, there by controlling current flow between them. The transistor characteristics depend on their type.

Transistors are made from the n-type and p-type semiconductor materials as diodes and employ the same principles. Transistors have two PN junctions instead of just one like a diode has. The two PN junctions allow a transistor to perform more functions than a diode, such as acting as a witch or an amplifier.


The bipolar transistor is made up of three parts: the emitter, the base and the collector. There are two types of bipolar transistors: the PNP transistor and the NPN transistor.



In the PNP transistor the emitter made from p-type semiconductor material, the base is made from n-type semiconductor material and the collector is p-type semiconductor material. For the PNP transistor to operate, the emitter must connect to positive, the base to negative and the collector to negative.

In the NPN transistor the emitter made from n-type semiconductor material, the base is made from p-type semiconductor material and the collector is n-type semiconductor material. For the NPN transistor to operate, the emitter must connect to negative, the base to positive and the collector to positive.




What is Semiconductor


The semiconductors are just average conductors, a higher resistance than metal conductors, but a lower resistance than insulators. The two most commonly used semiconductor elements are Silicon and Germanium. Their +4 valence electrons mean that they have a very stable covalent bond structure.

Intrinsic semiconductors are pure semiconductors that contain no impurities. When temperature increases, the conduction property of the intrinsic type also increases. This is because, at high temperatures, electrons are excited to higher energy levels and create holes. These holes are positively charged and flow in the direction opposite to that of electrons thus causing electricity. In an intrinsic semiconductor, the number of holes and electrons are equal. Other causal agent of electricity in this type is crystal defects.

Extrinsic semiconductors when impurities are added to intrinsic semiconductors, extrinsic semiconductors are formed, meaning they are not in their natural form. The process of adding impurities to the semiconductor is called doping.

Doping a pure semiconductor with a small amount of material with a valence electron of  +5 (which inclues Phosphorus, Arsenic, and Anitmony) creates an n-type semiconductor. It is referred to this because of the excess of free electrons in the material.
Similiarly, doping a pure semiconductor with a small amount of material with valence electron of +3 (Boron, Aluminum, Gallium, and Indium) creates a p-type semiconductor. This results because of a hole that is left by the absence of an electron in the covalent bond structure.


Note that doping a semiconductor does not add or remove any charge. The resulting product is still electrically neutral. Doping simply redistributes valence electrons so more or less free charges are available for conduction.

The PN Junction is formed by joining n-type and p-type semiconductor. The extra electrons in the n-type semiconductor attempt to move over into available holes in the p-type semiconductor. At the same time, some of the holes in the p-type seiconductor end up moving over to the n-type to meet up with electrons.When this happens, we end up with an excess of electrons on the p-type side and extra electrons on the n-type side, creating an electrical imbalance. This electrical imbalance is known as the barrier potential.




Forward Bias
When we apply a positive voltage to the p-type semiconductor and a negative voltage to the n-type semiconductor, we are applying a forward bias to the semiconductor. First, the negative voltage at the n-type semiconductor is going to attempt to push electrons towards the junction in the middle. The positive voltage at the p-type semiconductor will push the holes towards the barrier as well. This reduces the barrier potential. If the barrier potential is reduced enough, the charge carriers can move through the barrier and out the other side. This means that current flows.

Reverse Bias
Applying a reverse voltage to our semiconductor material is known as reverse bias. In this condition, the electrons are pulled away from the barrier on the n-type side and the holes are pulled away from the barrier on the p-type side. This results in a larger barrier, which creates a much greater resistance for charges to flow through. The net result is that no current flows through the barrier.