Basics: mosfet

1. About Mosfet

Field Effect Transistor Mosfet is ( M etal O xide S emiconductor F ield E ffect T ransistor) is a special Transistor structure and operations other than conventional transistors that we know, the Mosfet is the principle of operation based on performance chain from field to generate electricity, the components have a large input impedance preferred to amplify the weak signal source, Mosfet is used more in the Monitor power circuit, the source computer.

Field Effect Transistor Mosfet

2. Components and symbols of the Mosfet.

The symbol and pinout equivalent
between and Mosfet Transistor

* Components of the Mosfet.

The construction of a reverse channel Mosfet P

• G: Gate gate called
• S: Source called terminals
• D: Drain called the drain
• Mosfet N cocoons have two pieces of semiconductor type transistor P on the N, between two layers of PN insulated by layers SiO 2 two-piece transistor P is connected to the positive pole D and S, the N transistor connected to thin layer above then check out the ultra G.
• Mosfet power is the maximum G to S and the positive pole to pole G D is very large, longer resistor between positive and negative D S depends on the voltage difference between positive and negative G S (U GS )
• When voltage U GS = 0 the resistance R DS is very large, when the voltage U GS > 0 => the effect of the magnetic field makes the resistance R DS decreased, the voltage U GS greater the resistance R DS smaller .

3. The operating principle of the Mosfet

The circuit experiment .

Experiment operation of Mosfet

• Experiment : Power DC U D a D lamp poles on D and S of the MOSFET Q (for Mosfet upon reverse polarization), we see no bright lights means no current through the leg poles DS G not power.
• When the switch K1 is closed, the source U G for the poles to the voltage U GS GS > 0V => led lights Q1 => D light bulbs.
• When you switch off K1, positive voltage on the capacitor C1 (ceramic capacitors) remain the leading lights Q => proves there is no current through ultra-GS.
• When the switch K2 is closed, the voltage on the capacitor C1 area decreased by 0 => U GS = 0V => light is off
• => From the experiments above we see that the voltage placed on pin G is not generated in the GS as the voltage transistors typically only generate a magnetic field => make the resistance R DS drops.

4. Measure test Mosfet

• A Mosfet better : when measuring the impedance between the S and G with the G with D resistance by extremely (needles not measure up in both directions) and when G is free electricity, the impedance between D and S is infinity.

The test procedure is as follows:

Measuring Mosfet check back to see better.

• Step 1: Preparing to scale x1K W
• Step 2: Go for G a charge (to stick to black on red que G S or D)
• Step 3: After loading a charge to G is measured between D and S (D que que black on red S) => needle will go.
• Step 4: Chap G to D or G on S to exit power vacuum G.
• Step 5: After you get the DS power vacuum as measured G needles to step 3.
• => The result is so good Mosfet.

Measurement test that has been short reverse Mosfet

• Step 1: To watch thang x 1K W
• Measure between G and S or between G and D if the metal up = 0 W is the convolution
• Measuring between D and S, but both directions to measure metal = 0 W is the convolution DS

5. Application of the Mosfet in practice

Mosfet power pulses in the Monitor

Mosfet is used as a source of light Monitor

In the clock source of the Monitor or computers, people often use pairs of components are IC oscillators and Mosfet lights, vibrations generated from IC can be taken to a pulsed square feet of Mosfet G, at the time of the pulse is voltage> 0V => Mosfet leading lights, the pulse oscillation = 0V Mosfet interrupt => such a vibration created to control for continuous switching Mosfet formed continuously variable electrical current running through the primary winding => generate varying magnetic field induced on the secondary coil => gives the output voltage.

* Measurement of test Mosfet circuit.
When checking Mosfet circuit, we only need to scale x1 W and measure between D and S => If a way to reverse kim kim not measure up => Mosfet is normal, if both two-dimensional metal up = 0 W is the Mosfet has been short-DS.