Weak current College】 【electronic engineer the prerequisite knowledge (a)】.

Operational amplifier using simple peripheral components, in analog circuits and digital circuits are very widely used. Operational amplifiers have good them models, in the detailed performance parameters, there are several differences, but the principle and application of the approach.

Operational amplifier usually has two inputs, i.e. the input and reverse input, and only one output terminal. Part of the operational amplifier inter's two inputs and one output, there are also several improvements to the performance of compensation PIN.

-The strength of the resistance with the light of the significant changes. Therefore, can be used to produce smart curtains, lighting, camera, shutter automatically switch automatically regulator, etc.

Do a Reed pipe is able to learn through magnetic circuit on/off of electronic components. Do a Reed pipe internal composition by soft magnetic metal Reed, in a magnetic field, metal magnetic Reed to gather and be force to achieve the effect of access or disconnect

Coupling is passed signal, optocoupler nature then use light to complete delivery of electrical signals for the component, typically refers to a luminous part and receive parts correspond and produced in one of the electronic components. Usually four valid pin (i.e. four pin access circuit function) as a group.

Optocoupler advantage is the ability to easily implement power isolation, in the city of switching power supply first-level isolation is the most commonly used. In addition, computer peripherals, communication, and more application, a component can be integrated with multiple sets of optocoupler (per unit of at least four pins)

Piezoelectric ceramic chip to do performance excellent vibration detector, it is an electro-acoustic devices, plus audio to hear voltage; when subjected to vibration sound (produces mechanical deformation) after induction faintly voltage.

Welding, appropriate adjustments are welded, the soldering iron and solder wire (flux), three-point-in-one, full contact, when the welding Department have come the right solder and flux, solder wire should be withdrawn. Welding process usually in 2-3 seconds is appropriate.

Plants need the skills and practical experience. However, access to the main path of experience must be diligent hands, may set, tired.

Flux: pine perfume in the factory as flux. Members can amateur homemade, with industrial alcohol (medical alcohol more expensive, unnecessary) Fusion Rosin. Note: do not mix too much concentration to flexibility.

The role of capacitance with three words: "charging and discharging. "Don't underestimate these three words, just because these three words, capacitive divider by AC, DC; pass high-frequency AC, impede the low-frequency AC.

The role of capacitance with eight words, that: "every other pass-through submission, high and low. "The eight words are based on the" charging and discharging "three words out, don't understand it, first back to death he (she).

According to DC power supply output current size and after the class (circuit or product) on the power requirements to be optional filter capacitors, typically, every 1 ampere currents corresponds 1000UF-4700UF is more appropriate.

Inductance role, with four words: "electromagnetic conversion. "Don't underestimate these four words, just because those four words, inductance can cut off the AC, DC; pass through low-frequency AC, alternating current.

The role of inductance and eight words, that: "every traffic straight, pass low resistance. "The eight words are based on the" electromagnetic conversion "three words.

Inductance is a capacitance of arch enemy. In addition, there is such a feature inductance: current and magnetic field required. Current to disappear, the magnetic field disappear; magnetic field to disappear, the current will disappear; magnetic north or South Pole change, current polarity will change.

Inductance internal current and magnetic field has been "playing" the civil war, the current would like to change, the magnetic field is not changed; magnetic field would like to change the current bias does not allow changes. However, due to external causes, current and magnetic field might have to change.

To the inductance coil voltage, current, coupled with the think larger from zero, but objected to the magnetic field will, so current had slowly become larger; to get rid of voltage, current inductors from big becomes zero, but objected to the magnetic field, but the current loop is finished, the current has been forced to zero, the magnetic field will anger immediately ends the inductor produces very high voltage in an attempt to produce current and maintain current unchanged. The high voltage is high, or even cause damage to electronic components, which then self-inductance of the coil.

Give an inductance coil plus a variable magnetic field, as long as there is a closed loop coil, coil generates electric current. If no loop can produce a coil voltage at both ends. The purpose of generating voltage that attempts to generate electricity. When two or more wire ring with a Ferrite core (aggregation function of magnetic line) or with a magnetic coil current and magnetic field between will influence each other, and that current mutual induction phenomenon.

You can see, the inductance that a wire, inductance on DC resistance is very small, or even can be ignored. Inductor in AC showed great resistance.

Inductance in series, parallel is complex because it is a fact of inductance wires in a certain location route distribution, therefore, inductance in series, parallel with inductive position related (primarily interact with the magnetic field of a related), if you do not consider the effect of magnetic field and distributed capacitance, conductor resistance (Q value), then the effect is equivalent to the resistance in series and parallel effects.

The higher the frequency of alternating current, the greater the inductance of the impediment. The lower the frequency of alternating current, inductive impediment.

Inductance and capacitance of charged together in parallel, the capacitor discharge will give inductance, inductors generated magnetic field, the magnetic field will remain current, current will reverse the charge for capacitor, reverse charge and discharge, week willBy Shana ... If no wear and tear, or be able to complement this loss, stable oscillation.

The role and function of the diode with four words, "unidirectional conductive. "Diode common to rectification, detector, voltage, clamp, protection circuit, etc.

In the walkman series power supply circuit on a rectifier diode, reversed when the DC power supply, does not produce current, do not damage the WALKMAN.

To the diode (SI) and below the forward voltage 0.6V, diode basically does not have a current (reverse is even cannot produce current!), this voltage is called dead voltage, the voltage threshold, threshold voltage, such as on-voltage

The role and function of the transistor because four words: "a variable resistor. "As the equivalent of transistor resistance to unlimited variation, so the transistor can be used to design switch circuit, amplifier, turbulence circuitry.

Transistor for collector current is equal to the base current magnification, when multiplied by the base current to a certain level, the collecting electrode electric current for various reasons is not likely to increase, then the collecting electrode voltage is equal to or close to emitter voltage, equivalent to the value 0 Ohm resistor.

Convinced that an enlarged State trick triode: launch of bias, bias slip knot.

Transistor is the current master device, field effect tube is voltage control devices. Field effect transistor performance superior, but in discrete components, low power supply voltage adaptation than transistors.

FET is voltage control devices that can easily be static damage, therefore, field effect tube in mostly have protection diode.

SCR is actually a high speed, no mechanical contact electronic switch, the switch needs to go with a low current. This switch has a self-locking function, that is, after the withdrawal of mastering the current conduction is still able to maintain continuity, but once the cutoff, whilst maintaining the closing state.

Resistance is usually used for color-ring marking method. Color standard method that uses the Brown, red, Orange, yellow, green, blue, purple, grey, white, black, 10 color represents 1234567890 ten digits, gold, silver and two colors represent the ratio 0.1, 0.01 or error of 5%, 10%. The kit is accompanied by a color sample loop and variety of color-ring resistance

Common four road opposite points to read three significant digits, the first two represent a valid number, first 3 digits mean rate. Example: yellow purple gold, 3-digit number 472, effectively represents 47 x 102 (or plus two 0) equal to 4700, i.e. 4.7K ohm; such as: brown black gold, a three-digit number is 100, effectively represents 10 multiplied by 100 (or 0-0) equal to 10, 10 Ohm.

In the process, if the transistor's base electrode and other pin rooms do not have a one-way conductive properties of (or one-way conductive characteristics not obvious), all point to the transistor is bad; in addition, even if unilateral conductive properties of normal, but cannot be the base master or unstable, and also describes the transistor is bad, or poor performance.

SCR in mastering extreme plus the appropriate trigger currents, SCR can from fractured into on-State, this time, we cancel the mastery of fire, electric current, but still able to maintain on-Silicon controlled rectifier. If the start of the current flows through the Silicon-controlled rectifier, when less than the ability to maintain continuity, the SCR is off, until the next trigger when conducting.

As long ago as two thousand years ago, people would find it electric phenomena and magnetic phenomena. China as early as the warring States period (475 a 211 BC) was invent now Remembrancer. While mankind on electricity and magnetism of true knowledge and widely used, yet only a hundred years of history. In the first industrial revolution wave, many scientists on electric and magnetic phenomena now intensive study and thus achieved significant progress now. People find live objects, repulsive, attract the opposite sex, and magnetic phenomena are similar.

1785, France physicist, summarizing the predecessors on Coulomb electromagnetic phenomena on the basis of cognition, raise it later called "Coulomb" so that electrical and magnetic phenomena are now unified.

1800, Italy physicist v developed chemical batteries, use artificial means to obtain it for future generations of continuous battery, electrical and magnetic studies of the relationship between the creation of la first condition.

1822 year, United Kingdom of the Faraday in the past a lot of work on the basis of the law, made up of electromagnetic induction to prove it "magnetic" to produce "electric", this is the principle of generator and motor it laid the basis

United States artists Morse in 1837 in the predecessors on the basis of the design is more practical, use code transfer information telegram machine, write, in Washington, d.c. and Baltimore City, between the La world's first telegraph line.

1876, United States of Bell's invention you phone, the first simulation of human communication.

Has begun to be applied to human beings enter you wire communication era. United Kingdom of Maxwell in summing up the work on the basis of our predecessors, make it a complete set of "electromagnetic theory", performance for the four equations. This would later call "Maxwell's equations". Maxwell concludes: moving charge produces electromagnetic radiation, formed gradually outward propagation, invisible electromagnetic waves. Although he did not put forward the "radio" and the noun, but he was already of electromagnetic theory, "power told people," is to "wireless" communication.
Beginners electronic knowledge, please put "electricity" as "water", "circuit" means "sea"; then it solutions for several commonly used terms, control the physical understanding of several common electronic components and their functions; and finally doing some experiments.

Any electronic products are electronic components, electronics technology is to learn how electronic components.

Electronic components of the combination is now electronic circuit, this is the basics. There are now electronic components,Knowledge of electronic circuits, electronic tools can also be used, you should begin to practice it.

Learn the most possible benefit from electronic than self loading audio and power amplifier. Enjoy the music itself is a kind of beauty, but cannot use their results to enjoy it is to achieve a new level.

Understand your friends learn computer ratio doesn't understand electronic friend learning PC to was easy. Understand your friends computer is the computer internal to external, don't understand electronic friend is learned from the computer an external PC.

What is a "field"? Stadium often we are able to exercise a range, the electric field refers to electricity generation forcing a range, the magnetic field is defined as a magnetic force generation, others.