Knowledge of electronic technology Posts

315 MHz remote control circuit design

OOK modulation despite the performance is poor, yet its circuit is simple easy to implement, stable work, so it has been widely used in automobile, motorcycle alarm, warehouse door, and home security systems, almost without exception, the use of such circuit.

Early transmitter more use LC oscillators, frequency drift more serious. Watch the emergence of sound devices to solve the problem, and the frequency stability and crystals is the same, and the frequency of hundreds of megabytes, even thousands of MHZ. No times frequency, compared with crystals circuit extremely simple. The following two circuit for common transmitter circuit, by using sound table device, circuit work very stable, even if the hand grasp antenna, sound table or other parts of the circuit, and launch frequency are not drift. And figure than a, figure 2 of the transmitted power a few bigger. Up to 200 m above.

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Lights out delay circuit only to be incandescent lamp

Principle description: when closed when SW, normal light LAMP, C1 in the electrical put bare. SW disconnect, has begun to turn out the lights delay process. Current is D2 the whole into half wave, LAMP brightness descend immediately, as delay instructions. R1 to C1 charging, C1 voltage up slowly, but do not bring D1 breakdown, so is the cutting T3, T5 through R5 trigger, LAMP, don’t go out. R5 not too small, with can trigger T5 for degrees, otherwise T5 trigger too early will not enough C1 filling voltage. C1 charging to more than 24 V, D1 breakdown, T1 / T2 avalanche conduction, C1 base flow to provide T3, T3 saturated, T5 will no longer trigger. Lights. R1 * C1 decided to delay length, can be determined.

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Power a lecture series inductor

inductor
Inductor in electronic used in making although not a lot, but they are in the circuit are equally important. We think the inductor and capacitor, is also a kind of energy storage components, it can change electric energy for magnetic field, and in magnetic field store energy. Inductance is symbol L said, it is the basic unit of the Henry (H), commonly used baekho heng (mH) for the unit. It often and capacitor work together, form LC filters, LC oscillators, etc. In addition, people still use the inductance of the characteristic, manufacturing the resistance flow circle, transformers, relays, etc.
The characteristics of the inductor with the characteristics of capacitance on the contrary, it has to stop alternating current and direct current through the characteristics of let through.
Small radio on many inductance coil, is almost a wire enameled wire with the hollow coil skeleton, the magnetic cores in or around on from the system. Have antenna coil (it is to use in the iron wire enameled wire from the system), intermediate frequency transformer (known as the weeks), input/output transformer, etc.
transformer
Is the core and around the insulation of copper wire circle line on the skeleton of the form. Insulation wire around the plastic skeleton, each frame around the system input and output to two groups of coil. Coil use among insulating isolation. After many around the core chip will be stuck in the middle of the plastic frame. So that we can make the inductance coil is significantly increased. Transformer using electromagnetic induction principle from its a winding to another son a winding of electric power transmission. Transformer in a circuit has important function: coupling ac signal and blocking dc signal, and can change the input/output voltage ratio; Use the circuit transformer on both ends of the impedance matching get good, in order to get maximum transmission power.
Power transformer is put into civil utility the high-tension electricity, and many of our electric is use the low voltage dc power of the job, need to use the 220 V ac power transformer utility transform into low voltage ac, again through the diode rectifier, capacitors filtering, form for electric dc motor. TV sets to tens of thousands of volts austeniticstainless voltage to work, is by the “line output transformer” supply.
Of course, the power transformer also has its many disadvantages, such as power and the proportional to the, heavy, the low efficiency, are now being new type of “electronic transformer” replaced. Electronic transformer is generally “switch power supply”, the computer work need several groups of switch power supply voltage is, color TV, display is no exception with switching power supply.
relay
Is the electronic and mechanical switch, it is to use paint bag in a round copper wire core around the circle on hundreds of thousands of circle to, when the coil current flows, round the iron core is produced the magnetic field, the core of the round with contact pieces of above to absorb iron plate, disconnect the first contacts and through to the second switch contacts. When the coil without electricity, iron core lose magnetic, because contact the elasticity of the copper effect, make the iron away from iron core, restoration and the first contacts the through. Therefore, can use small current to control other circuit switch. The relay made of plastic or organic glass dust-proof covers protected, some or all of the seal to avoid shock oxidation.

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Power line carrier-current communication (LMl893) integrated circuit

Power line carrier-current communication technology can be widely used in industrial automatic control system, power management systems, and household electrical appliances control system, fire alarm system and the computer terminal interface and so on. It use existing power line to transmit information, the need for additional erection line, also do not take up the existing communication frequency resource. Therefore, particularly applicable to form a small local area network and realize the automatic control within the building.

The main functions and characteristics of LMl893

LM1893 is the NS company produces the power line carrier-current communication integrated circuit. Can complete serial data half duplex communication, have to send and receive data fully functional, and controller and some peripheral components can be integral to the power line carrier-current communication system. With the application of the chip system consisting of the score of the set components system has high sensitivity, anti-jamming advantages.

LMl893 has the following characteristics:

1. The resistance of the noise FSK modulation;

2. The data rate is as high as 4.8 KB5

3. The drive to reduce rf circuit sine wave interference;

4. The output power can promote l0 times;

5. The carrier frequency in 50 kHz-300 kHz can choose between;

6. And TTL, CM0S level compatible;

7. For the existing various power line.

This article from the Fabrication Services

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Focus on super capacitor selection and application

Super capacitor and battery is energy storage carrier, but both have different characteristics. Super capacitance through the medium separation of positive and negative way to store energy, is the physical methods energy storage, and the battery is through the method of chemical reaction to energy storage. Super capacitor cycle count can reach one million times, and the battery only 1000 times, obviously super capacitor life will far outweigh battery, reduce maintenance cost and good for the environment.

Super capacitor charging and discharging speed and could start in locomotive provide energy, brake capture energy, because the super capacitor charging and discharging time in 1 seconds, as it happens and locomotive brake or start time matching. Other equipment such as wind power, JiBian rotor blades to provide energy but also in this time period. And the battery charge and discharge of about 1 hour to 10 in hours or so, but the traditional used in filter capacitance, charge and discharge for 0.03 seconds.

Super capacitance discharge speed, and capacity, can the instantaneous release huge energy, can be used as a standby power, and in the system when suddenly loses power, in a very short time for the system to provide the energy. Super capacitor can also be used as a engine or power battery auxiliary, improve the engine’s efficiency and energy utilization efficiency. In system startup, super capacitance will capture the energy released, meet peak power requirements, and to lessen the burden of battery or engine.

In addition, super capacitor can also used for automatic meter reading system in intelligent electric meter (water meter, gas meter), camera flash, a hybrid car. Super capacitor energy saving, environmental protection, and efficient characteristics catering to the current energy saving carbon reduction design appeal. This focus on super capacitor, through the following three introduced super capacitor:

Super capacitor basic principle and characteristics

Super capacitor belong to electric double layer capacitors, it is the world has made in inputs, electric double layer in the largest capacitor capacity, the basic principle and other kinds of electric double layer capacitors, make use of activated carbon electrode and electrolyte of porous electric double layer structure for large capacity.

Super capacitor and battery comparison

Relative lead-acid battery, nickel cadmium battery, lithium ion battery, super capacitors have energy-saving, long service life, safe, environmental protection, wide temperature range, charging fast, no artificial maintenance. This article through the chart to contrast different energy storage product features.

The typical application of super capacitor and selection

Super capacitor capacity, charging and discharging speed, and recharge cycles can reach one million times, very suitable for used as a backup power supply and provide peak power. This paper introduces the working principle of super capacitors, and mainly introduces in container crane and the application of smart meters.

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The instrument system the common failures that analysis steps

【 abstract 】 : now, along with petrochemical, steel, paper, food, pharmaceutical enterprise automation level unceasing enhancement, the instrument maintenance personnel to the technical level raised taller requirement. Reduce the processing time for instrument faults, ensure the safety production to improve the economic benefit, this paper published a little instrument site maintenance experience, for instrument maintenance personnel reference.

Now, along with petrochemical, steel, paper, food, pharmaceutical enterprise automation level unceasing enhancement, the instrument maintenance personnel to the technical level raised taller requirement. Reduce the processing time for instrument faults, ensure the safety production to improve the economic benefit, this paper published a little instrument site maintenance experience, for instrument maintenance personnel reference.

A, the field instruments system fault analysis of the basic steps

The instrument measuring parameters are generally divided into temperature, pressure, and flow, liquid level four parameters.

We, according to the different measuring parameters, to analyze the different field instruments for the source of the problems.

1. First of all, on the analysis of the fault before field instruments, have to compare a thorough understanding of relevant instrument system of production process, production process and conditions, understand the instrument system design scheme, design intention, the structure of the instrument system, properties, characteristics and parameters requirements, etc.

2. Check the field instruments on the analysis of the system failure before going to the operating workers know the load and the raw material production of parameter change, check the record curve fault instrument, and make comprehensive analysis to determine instrument faults the reason.

3. If meter records for a dead line curve (a little change also not line says dead line), or record original curve for wave, now suddenly become a straight line; Failure is likely in the instrument system. Because the current record instrument are mostly DCS computer system, the sensitivity is very high, the change of the parameters can very sensitive reaction comes out. At this point, people change process parameters, see curve changes. If you don’t change, basic concluded that is a problem instrument system; If have the normal change, basic judge instrumentation systems don’t have big problems.

4. Change process parameters, and found that mutations or jump to record curve maximum or minimum, at this time of failure often in the instrument system.

5. Fault was developed instrument document curve has been appear normal, volatile record curve have become law after or is difficult to control system, even in manual operation can’t control, this time the fault may be caused by the process operating system.

6. When found DCS display instrument is not normal, can go to the same visual inspection instrument instructions value, if they difference is very big, may be instrument system malfunction.

In short, analysis the field instruments when the cause of the problem, we must pay special attention to be measured and the characteristics of the control valve control object changes, all of these may cause the instrument system is the cause of the trouble. So, we should from the field instruments system and process operating system two comprehensive consideration, careful analysis, check the reason.

Two, four measuring parameters instrument control system fault analysis steps

1. The temperature control instrument system failure analysis steps

Temperature control instrument analysis system failure, you should pay attention to two points: the system with electric meter measuring instrument, the instructions, control; The system of measurement instruments often large time.

(1) temperature instruments system instructions value suddenly to a maximum or minimum, generally for instrument system failure. Because the temperature measurement instrument system lags behind larger, won’t happen suddenly change. At this time of the cause of the problem is more heat resistance, thermocouple, compensation conductor or transmitter amplifier caused by failure break.

(2) temperature control instrument systems instructions appeared fast oscillation phenomena, PID control parameter improper adjustment.

(3) temperature control instrument systems instructions face a slow wave, probably due to the change process operation, such as process operation at that time did not change, may be instrument control system itself fault.

(4) temperature control system itself the failure analysis steps: check the regulator input signal whether changes, the input signal does not change, the regulator movement, the regulator film head the diaphragm leak; Check the regulator locator input signal whether changes, the input signal does not change, change the output signal, the locator have fault; Check the locator input signal have change, look adjustment output for change, if the regulator input don’t change, output change, this is the fault regulator itself.

2. Pressure control instrument system failure analysis steps

(1) pressure control system instrument instructions appeared fast oscillation fluctuation, the first check process operation for change that is mostly process operation, and regulator PID parameters setting caused by bad.

(2) pressure control system instrument instructions appeared dead line, the pressure change process operation instructions or not to change, general fault appears in pressure measuring system, the first check the measuring pressure if there is lead ductal system of blocking phenomenon, not blocking, check pressure transmitter output system for change, change, fault in the controller measurement indicator system.

3. Flow control instrument system failure analysis steps

(1) flow control instrument system instructions to the value of hours, first check the field detection instrument, if the normal, the fault in the display instrument. When the field detection instrument instructions minimal, then check the regulator open degree, if the regulator opening is zero, it is often the regulator to fault between regulator. When the field detection instrument minimum instructions, the regulator opening normal, fault reason is quite likely the system pressure is not enough, system pipeline jams, pump not the quantity on the crystallization, medium, causes such as improper operation. If instrument malfunction, reasons for orifice plate differential pressure flow meter may be positive pressure led pressure catheter plugging; Differential pressure transmitter positive pressure chamber leak; Mechanical flowmeter is gear jammed or screen plugging, etc.

(2) flow control instrument system instructions to maximize value, the measurement instrument often instruction is the largest. This time can be manual remote control regulator open big or small shut, if can flow down is commonly for process operation causes. If flow value drop not come down, is the instrument system of the causes, check the flow control instrument system regulator is action; Check the meter measuring lead pressure system is normal; Inspection instrument signal transmission system is normal or not.

(3) flow control instrument system are more frequent fluctuations indicating value, can be changed to control manual, if fluctuations decrease, is the instrument of the reasons of the PID control parameters or instrument improper, if still frequent fluctuations, is the process operation causes.

4. Liquid level control instrument system failure analysis steps

(1) level control instrument system changes to the largest indicating value or the hours, can check to see if the normal inspection instruments, such as indicating normal, will level control to manual remote control level, see level changes. Such as liquid level can be stable in a certain range, the fault in the liquid level control system; If not steady level, it is commonly process system caused by fault, from the process to determine the cause.

(2) the differential pressure type fluid control instrument instructions and the direct reading type indicating meter on the instructions, the first check the direct reading type indicating meter is normal or not, such as indicating normal, check differential pressure type fluid instrument of negative pressure seal the liquid pressure pipe whether have leakage; If there is leaking, and to pouring sealant liquid, and the zero; No leakage, may be the negative transfer of instrument is wrong, readjust the traffics makes the gauge instructions to normal.

(3) liquid level control instrument systems instructions value change frequent fluctuations, the first analysis of liquid level control object size capacity, to the analysis of the cause of the failure, large capacity is usually caused by instrument faults. Capacity of the first small analysis process operation conditions are have change, if any change is likely to be caused by frequent fluctuations of the process. If no changes may be caused by instrument faults.

This article from the Hardware Appliances Exporters

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Identify true and false solid capacitance

Solid capacitance

Called the: solid aluminum electrolytic capacitors. It and ordinary capacitance (i.e. liquid aluminum electrolytic capacitors) the biggest difference is that with a different dielectric material, liquid aluminum capacitor dielectric material for the electrolyte, and solid capacitor dielectric material is conductive polymer.

The solid capacitance and in where? To often go to net cafe or long time use computer friend, certainly have or heard as motherboard capacitance lead to unstable computer, even the mainboard capacitance burst of things! That’s because on one hand the motherboard with a long time use to overheating electrolyte expands, cause capacitance lose their effect even because of more than boiling point lead to inflation burst! On the other hand, if the motherboard with no electricity in the case of a long-term, electrolyte easy and alumina form chemical reaction, cause boot or when a current form the phenomenon of the explosion. But if the solid capacitance, there is no such hidden dangers and dangerous!

Because the conductivity of polymer solid capacitance products as dielectric, this material is not and alumina produce effect, after electrify not explode phenomenon; At the same time it for solid products, nature also does not exist because expands lead to burst.

Solid capacitance have environmental protection, low impedance, high temperature stability, high ripple resistance high riliability and superior characteristic, is the highest in electrolytic capacitors products to order products. Because of solid capacitance characteristics is far better than liquid aluminum capacitors, solid capacitance temperature of 260 degrees Celsius, and electric conductivity, frequency characteristics and life are beautiful, suitable for the low voltage, high current application, mainly used in the digital products such as thin DVD, the projector and industrial computer, etc. But now in the personal computer on the main board more and more appear a lot of solid capacitance, even all the solid and no longer the electrolytic capacitor, make solid capacitance “civilian” popular, but not just using too hard in electronic instruments and industrial computer.

The classification of capacitance: capacitance is two pieces of conductor (anode and cathode) between them with an insulator (media) consists of the electronic components, due to the particularity of its structure, so classification approach

A variety of, according to the media, usually anodes, cathode and process the four classification approach, and all kinds of classification approach cross overlap each other, can say chaos:

The right is a simple, is not complete classification of capacitance, the main list some equipment in the card on the most common type of capacitance, through the intuitive tree to the classification of the table can be capacitance, naming a the direct-viewing understanding. Commonly used capacitance have electrolyte capacitance, solid-state capacitance and tantalum capacitance.

In the eyes of many users, motherboard, video card, industrial control board and other products whether to use solid capacitance, decided the boards are in high grade. General use this kind of relatively high solid capacitance, the corresponding resistance to choose a product can be assured than the letter resistance, resistance JEPSUN advantage and solid capacitance similar, high precision, good stability, low resistance, but super power, current products such as sampling is used to power. Solid capacitance two this years in domestic technology development is rapid, by original SANYO monolith, now many domestic and foreign brands die the world. Solid capacitance has walked down the shrines, many ordinary video, digital products are the use of this kind of product, here is a solid capacitance similar to common aluminum electrolytic capacitor, part can be replaced, and another a solid capacitance, flake, used to replace common tantalum capacitance.

Identify true and false solid capacitance:

A purple patch, sanyo aluminum housing OS-CON solid capacitance

The real solid capacitance the capacitance is recognized as the best interface card capacitance, the good patch type process, but cost should also is the highest of a kind of it. Is divided into several levels, such as SVP series (also seems to have straight into the package.

Second, aluminum shell solid capacitance

Not top, but also is very good for the most common Japanese chemical Nipponchemicon (NCC) PS aluminum polymer ultra-low resistance series, USES the straight insert process, although no purple sanyo of good, but also is very good capacitance.

Three, aluminum shell L8 solid capacitance

Economical solid capacitance than before both to almost, but wins in price, general at the low end of claims on the main board of the solid state capacitance power supply can see!

Four, yellow * * * color R5 solid capacitance

At present, in AngDa and seven on the main board, see R5 solid capacitance can more. Always use the older version of the R5 seems very the right things, do not deny R5 is now on the main board of the application of top electrolysis, five hair’s esr, generally solid electrolytic advantage than liquid, such as low temperature will not affect esr too much, each reduce 20 degrees Celsius life increased 10 times, and electrolysis is 4 times. So-called military level Fujitsu solid capacitance, the most common in the seven and AngDa motherboard, quality and performance is still let a person be at ease, with the capacitance of the board is not that easy to suddenly and violently pulp.

Five, electrolytic aluminum electrolysis patch shell

Left 1) patch type electrolytic capacitors (left 2) aluminum shell solid capacitance (can see explosion-proof lines) there is a very simple to identify the solid and the method of electrolytic capacitor, see whether top have X shape or K shape of explosion-proof lines, commonly is electrolytic! Some electrolytic also USES patch type design, and some electrolytic outsourcing a layer of aluminum shell, be some manufacturer out suddenly users say solid capacitance.

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How to judge transistor’s pin

Transistor’s tube and tube type of discrimination is electronic technology feet beginner’s a basic skills, in order to help the reader quickly to master the method, in this sums up the four sentences formula: “three reverse, find base; PN junction tube type, set the arrows, deflection;; the uncertainty, move your mouth.”

A, three reverse, find base

You know, transistor is containing two PN junction of semiconductor devices. According to two PN junction connect different ways, can be divided into NPN type and PNP type two kinds of different conductive type of transistor.

To use the electric meter universal test transistor in ohms block, and choose R x 100 or R x 1 k moving off. Figure 2 map out the multi-purpose electric meter ohm to block of equivalent circuit. Red pens and the connected is shown in the table, the battery anode, black is connected with pens and inside the watch battery positive.

Suppose that we don’t know is measured transistor type NPN or PNP type, also can’t tell what is the tube feet electrode. The first step is to judge test which tube foot is the base. At this time, we take as two electrodes (such as the two electrodes are 1, 2), with the multi-purpose electric meter two pens and reverse the measurement of it is, reverse resistance, observe the deflection Angle whose hands; Then, take again 1, 3 two electrodes and 2, 3 two electrodes, reverse respectively measuring their are, reverse resistance, observe the deflection Angle anlaogue display. In these three times in the measurement of reverse, there must be two measurement results are close to each other: that is in the measurement of reverse a deflection anlaogue display, a deflection is small; An inevitable is reversed left before and after the deflection Angle measurement pointer is very small, this time did not measure of that just feet is that we want to look for the base of.

Second, PN junction, set tube type

Find out transistor’s base, then we can according to the base and the other two electrodes PN junction between the direction of the conductive to determine the pipe type. Will the multimeter black pens and contact base, red pens and two other electrode contact with any of the electrode, if headers to deflect a pointer Angle, the instructions are measured for NPN transistor type pipe; If the pointer deflection Angle header is very small, is that the tube for PNP type.

Three, the arrows, deflection

Find out the base b, the other two electrodes which is the collector c, which is holding emitter e? Then we can be measured with a current through ICEO method to determine the collector c and emitter e.

(1) for NPN transistor type, through current measurement circuit. According to this principle, with universal meter black, red pens and reverse the measurement of the poles are between, reverse resistance Rce and Rec, although two measurement of the deflection Angle multimeter pointer is very small, but observe carefully, there will be a slightly bigger deflection Angle, and at the time of the current flow must be: black, c and b, pens and extremely extremely, extremely-red pens and e, current flow as it happens and transistor symbol the arrows in direction (” the arrow “), so now that answered the pens and black must be collector c, red pens and have answered the must be emitter e.

(2) PNP transistor type for the, the truth also is similar to NPN type, its current direction must be: black and extremely-b e pens and very, very-red pens and c, the current direction and with the direction of arrow transistor symbols so at this moment, the black pens and answered the must be emitter e, red pens and have answered the must be collector c.

Four, measure out, move your mouth

If in the arrows, deflection big “measurement process, if because of two measurement and reverse the pointer deflection are too small when it is difficult to distinguish, will” move your mouth “. Specific means is: in the arrows, deflection big “of two measurement, with two hands are two pens and knead with tube feet road.the mouth contains live (or use the tongue withstand) and electrode b, still use the arrow, deflection big” identifying method can separate the collector c and emitter e. Among them the human body have a dc offset the role of resistance, the purpose is to make the effect is more apparent.

This article from the Mechanical Parts

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Key type diode and alloy type diode

Key type diode

Key type in germanium or silicon diode is the single chip welding or silver thread and form. The characteristics of contacts between the diode and the alloy type diode. Compared with contacts type, although key type of the diode’s PN junction electric capacity increases slightly, but positive characteristic especially good. Many used to be switch, is sometimes used in the detection and power rectifier (less than 50 mA). In key type diode, welding gold-rimmed diodes are sometimes called JinJian type, welding silver of the diode is sometimes called silver key type.

Alloy type diode

In N type of germanium or silicon single chip, through the alloy, aluminum and other metal indium method of making PN junction and form. The forward voltage drop small, and is suitable for large current rectifier. Because of its PN junction when large capacity reverse static electricity, so is not suitable for high frequency detection and high frequency rectifier.

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Plane type diode

In a semiconductor of single crystal (mostly is n-type determined piece), and the diffusion P type impurities, use silicon wafer surface oxidation film of shielding effect, in N type of determined only selectively diffusion formed part of PN junction. Therefore, do not need to adjust the PN junction area of drug corrosion function. Due to the semiconductor surface is flat production, so its name. And, the surface of the combined PN, because be oxidation film cover, so acknowledged to be the good stability and life long type. At first, for the semiconductor material is used by extension of the formation of the law, so it is also the plane type called extension plane type. For Food Industry plane type diode speaking, seems to be used in large current rectifier with model very few, and for the small current switch with model is a lot.

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