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Bi-color LED indication

Bi-color LEDs are the same LEDs as uni-color, just there is more than one LED housed in one package. Bi-color LEDs may have two or three leads depending on the intentional connection method. Three lead LEDs have a common cathode lead to which both LEDs are connected internally. To tun one of the LEDs or at the same time, connect the cathode to the ground via a current limiting resistor which value is equal to one LED required limiting. Of course, you can connect current limiting resistors to each of the anodes and control current individually. Then you can apply power to one of the anodes or both at the same time to have bi-color amber illumination.

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Using NVRAM in embedded projects

NVRAM(Non-Volatile Random Access Memory) is one of the non-volatile memory selections. This may be an alternative to EEPROM to back up the memory. NVRAM chips can be used for nonvolatile memory storage with many benefits comparing to EEPROM. The main benefit is that NVRAM chips work like static RAM. They are RAM; they contain a lithium cell battery for retaining RAM contents when the main power is switched off. The backup memory can store contents as long as the battery provides power. NVRAM chips don’t require much power; backup can be guaranteed for up to ten years. For instance lets take Dallas NVRAM chip DS1225.

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How does RFID tag technology works

RFID introduction RFID tagging technology is successfully used among us. Still, we don’t notice them always and do not think about them as they are not noticeable because we do not have to take any actions to transfer or read any information from RFID tags. But probably everyone notices in big supermarkets, book stores two parallel frame antennas and thicker labels on products you buy, or maybe you have an RFID entrance card at your work. So let’s see how this technology works. RFID is a so-called Radio Frequency Identification system that consists of two main parts: transmitter and receiver. The labels, access cards, and even passports in some countries have RFID transponders integrated. These transponders are called tags. Each tag has information programmed in it. A reader can read this information via the Radio Frequency link. Tags can be very miniature, like thicker paper sheets. The simplest ones have only an antenna and diode. These tags only reflect signals incoming from transmitters. These are tags that are used in supermarkets and other places for securing goods from stealing. If the signal is reflected, an alarm is triggered. When the seller scans the tag, it is electrically destroyed to trigger…

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Easy way to measure motor torque

Motor torque (momentum) is one of the motor ratings used to indicate the rotary motor force produced on its output shaft. The motor torque rating is usually captured at the point when the motor is stalled. The torque measurement unit is (Nm) in the metric system or (ft-lbs) in the US system. But the principle is the same torque is a multiplication of lever length (r) and force(F) applied to lever: I=r x F So there is a simple experiment on how to measure motor torque quite accurately without any fancy measuring tools. All you need is a motor of which torque will be measured, a nominal power supply of motor, thread long enough, a mass of known weight, ruler, and a table or other lifted surface where the motor will be fixed.

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Testing pulse transformer with an oscilloscope

Pulse transformers are a little different from regular AC transformers. In AC transformers, magnetic flux alternates between negative and positive values in the core, while in pulse transformers, magnetic flux is unipolar. Pulse transformers are used in TV, computer power supplies. If you need to test a pulse transformer, it may be almost impossible to do this with an ohmmeter, even a digital one, because the windings of impulse transformers have meager active resistance except for high voltage ones. One way to test is to measure the inductance of windings and compare them to values in specifications. Still, not everyone has the ability to measure inductance, and not always you have transformed specifications near by. So there is another way to test pulse transformers, which may be acceptable to almost everyone radio-hobbyist, using a low-frequency generator that works at the resonance frequency of contour, which consists of external capacitor and pulse transformer winding.

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Measuring of electrical energy consumption

Electromechanical energy counters were popular for more than 50 years. Today, you can find them only in older houses or in low-budget appliances because today, electronic energy counters are taking their place. And there are many reasons to do so. For instance, measurement accuracy, flexibility, multi-rate support, memory, statistics, remote reading and control, automatic register, and so on. These features can be built into one small chip, which will serve with high reliability and low price. Let’s see how energy (active power) consumption is measured. Active power which is required in the form of alternate current (AC) can be calculated as average power over one period:

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Oscilloscope probes for accurate signal measurements

Oscilloscope Probes Measuring signals with oscilloscopes may be a challenging task especially high-frequency ones. Without proper oscilloscope probes, correct measurement of high-speed time-domain signals wouldn’t be possible. For high-speed measurement, you should consider signal parameters like amplitude, source impedance, rise time and bandwidth. There is a wide variety of probes available – passive, active, current-measurement, optical, high voltage, and differential. But let’s narrow the discussion to probes used to measure signals with wide bandwidth and short rise times. There are also many variations on what probe is proper. As probes are potential load to measured circuits, it is important to know their sensitivity to resistive, capacitive, or inductive loading. Incorrectly chosen probes (like high capacitance) can distort the fast-rising signal. Some circuits may not tolerate probes at all (high-speed amplifiers).

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Reliable soldering with fluxes

Reliable soldering can be achieved by soldering clean surfaces. Usually, surfaces are cleaned with abrasives and solvents, but after the surface is cleaned surface immediately oxides, especially when heated. During oxidation, the surface is covered by thin oxide film, which prevents solder from contacting metal. This is why flux is used in the soldering process. To remove/deoxidize, surface flux must be applied during soldering. Flux chemically removes surface oxide when heated and makes a good metal to solder contact. There are several categories of soldering fluxes: Acid Flux (or commonly known fluxes: Zinc chloride, hydrochloric, ammoniac); Organic Flux; Rosin Flux. Each flux has its own specifics and may be used for different soldering technologies.

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What is worst-case timing analysis

Many of your PC hardware people have probably faced similar problems when assembling a computer from different parts, and it seemed to work properly. But under some circumstances system crashes without any known reason. Even in my practice, I had a sound-card that works well, but time at the time, it just crashes, and then the computer hangs. Of course, I can blame drivers or operating systems, but there is another probability that there can some timing failures occur. Many complex productions around us may have many undefined failures due to a lack of timing worst-case analysis. Failures may occur due to power supply fluctuations, thermal changes, or other conditions. Worst-case analysis encounters all available information of condition variations that can affect the performance of components. The worst-case analysis shows if electronic design meets specifications under variable conditions like temperature, voltage, or other variables. Only detailed analysis can prove if the design will work reliably under all operating conditions. It is proved that it is much better to design reliable hardware than fix the problems later. In many ways, the worst-case analysis may be implemented in various manufacturing phases automatically. By including several simple tests may save lots of money…

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Chemical effects of electricity

Electronics depend on chemistry more than you can imagine. To generate electricity, there are many methods used; one of them is chemical. Remember batteries, where electricity is generated because of chemical reactions inside the cell. In conductors like liquids and gases, electricity is carried not by electrons in solid constructions(copper, aluminum, etc.) but by ions – molecules with electric charges. Even non-distilled water contains enough ions to be conductive. Let’s go through several chemical effects of electricity. Electrolysis Electrolysis decomposes the liquid compound by passing an electric current through a liquid called an electrolyte(saltwater, copper sulfate, sulphuric acid). Electrolysis is used very widely in the industry, like electroplating metals, refining copper, and extraction of aluminum from ore. To make electrolysis happen, two conductors used cathode(-) and anode(-).

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