Delay using 8051 timer.

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 The 8051 microcontroller has two independent 16 bit up counting timers named Timer 0 and Timer 1 and this article is about generating time delays using the 8051 timers. Generating delay using pure software loops have been already discussed here but such delays are poor in accuracy and cannot be used in sensitive applications. Delay using timer is the most accurate and surely the best method.
A timer can be generalized as a multi-bit counter which increments/decrements itself on receiving a clock signal and produces an interrupt signal up on roll over. When the counter is running on the processor’s clock , it is called a “Timer”, which counts a predefined number of processor clock pulses and  generates a programmable delay. When the counter is running on an external clock source (may be a periodic or aperiodic external signal) it is called a “Counter” itself and it can be used for counting external events.
In  8051, the oscillator output is divided by 12 using a divide by 12 network and then fed to the Timer as the clock signal. That means for an 8051 running at 12MHz, the timer clock input will be  1MHz. That means the the timer advances once in every 1uS and the maximum time delay possible using a single 8051 timer is ( 2^16) x (1µS) = 65536µS. Delays longer than this can be implemented by writing up a basic delay program using timer and then looping it for a required number of time. We will see all these in detail in next sections of this article.
Designing a delay program using 8051 timers.
While designing delay programs in 8051, calculating the initial value that has to be loaded inot TH and TL registers forms a very important thing. Let us see how it is done.
  • Assume the processor is clocked by a 12MHz crystal.
  • That means, the timer clock input will be 12MHz/12 = 1MHz
  • That means, the time taken for the timer to make one increment = 1/1MHz = 1uS
  • For a time delay of “X” uS the timer has to make “X” increments.
  • 2^16 = 65536 is the maximim number of counts possible for a 16 bit timer.
  • Let TH be the value value that has to be loaded to TH registed and TL be the value that has to be loaded to TL register.
  • Then, THTL =  Hexadecimal equivalent of (65536-X) where (65536-X) is considered in decimal.
Let the required delay be 1000uS (ie; 1mS).
That means X = 1000
65536 – X =  65536 – 1000 = 64536.
64536 is considered in decimal and converting it t0 hexadecimal gives FC18
That means THTL = FC18
Therefore TH=FC and TL=18
Program for generating 1mS delay using 8051 timer.
The program shown below can be used for generating 1mS delay and it is written as a subroutine so that you can call it anywhere in the program. Also you can put this in a loop for creating longer time delays (multiples of 1mS). Here Timer 0 of 8051 is used and it is operating in MODE1 (16 bit timer).
DELAY: MOV TMOD,#00000001B // Sets Timer 0 to MODE1 (16 bit timer). Timer 1 is not used
       MOV TH0,#0FCH // Loads TH0 register with FCH
       MOV TL0,#018H // LOads TL0 register with 18H
       SETB TR0 // Starts the Timer 0
HERE: JNB TF0,HERE // Loops here until TF0 is set (ie;until roll over)
      CLR TR0 // Stops Timer 0
      CLR TF0 // Clears TF0 flag
The above delay routine can be looped twice in order to get a 2mS delay and it is shown in the program below.
      DJNZ R6,LOOP

DELAY: MOV TMOD,#00000001B
       MOV TH0,#0FCH
       MOV TL0,#018H
       SETB TR0
      CLR TR0
      CLR TF0
Few points to remember while using timers.
  • Once timer flag (TF) is set, the programmer must clear it before it can be set again.
  • The timer does not stop after the timer flag is set. The programmer must clear the TR bit in order to stop the timer.
  • Once the timer overflows, the programmer must reload the initial start values to the TH and TL registers to begin counting up from.
  • We can configure the desired timer to create an interrupt when the TF flag is set.
  • If  interrupt is not used, then we have to check the timer flag (TF) is set using some conditional branching instruction. 
  • Maximum delay possible using a single 8051 timer is 65536µS and minimum is 1µS provided that you are using a 12MHz crystal for clocking the microcontroller.

Square wave generation using 8051 timer.

Square waves of any frequency (limited by the controller specifications) can be generated using the 8051 timer. The technique is very simple. Write up a delay subroutine with delay equal to half the time period of the square wave. Make any port pin high and call the delay subroutine. After the delay subroutine is finished, make the corresponding port pin low and call the delay subroutine gain. After the subroutine  is finished , repeat the cycle again. The result will be a square wave of the desired frequency at the selected port pin. The circuit diagram is shown below and it can be used for any square wave, but the program has to be accordingly. Programs for different square waves are shown below the circuit diagram.

Square wave generation using 8051 timer
1KHz Square wave using 8051 timer.
MOV P1,#00000000B
MOV TMOD,#00000001B
      CLR P1.0
       MOV TL0,#00CH
       SETB TR0
      CLR TR0
      CLR TF0
      SETB P1.0
2 KHz Square wave using 8051 timer.
MOV P1,#00000000B
MOV TMOD,#00000001B
      CLR P1.0
       MOV TL0,#018H
       SETB TR0
     CLR TR0
     CLR TF0
     SETB P1.0
10 KHz square wave using 8051 timer.
MOV P1,#00000000B
MOV TMOD,#00000001B
      CLR P1.0
       MOV TL0,#0CEH
       SETB TR0
     CLR TR0
     CLR TF0
     SETB P1.0
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MAKE 12V TO 240 V

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RF Based Wireless Remote Control System

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It is often required to switch electrical appliances from a distance without being a direct line of sight between the transmitter and receiver. As you may well know, an RF based wireless remote control system (RF Transmitter & RF Receiver) can be used to control an output load from a remote place. RF transmitter , as the name suggests, uses radio frequency to send the signals at a particular frequency and a baud rate.
The RF receiver can receive these signals only if it is configured for the pre-defined signal/data pattern. An ideal solution for this application is provided by compact transmitter and receiver modules, which operate at a frequency of 434 MHz and are available ready-made. Here, the radio frequency (RF) transmission system employs Amplitude Shift Keying (ASK) with transmitter (and receiver) operating at 434 MHz. The use of the ready-made RF module simplifies the construction of a wireless remote control system and also makes it more reliable.

RF Transmitter

This simple RF transmitter, consisting of a 434MHz license-exempt Transmitter module and an encoder IC , was designed to remotely switch simple appliances on and off. The RF part consists of a standard 434MHz transmitter module, which works at a frequency of 433.92 MHz and has a range of about 400m according to the manufacture. The transmitter module has four pins. Apart from “Data” and the “Vcc” pin, there is a common ground (GND) for data and supply. Last is the RF output (ANT) pin.
Pin Assignment of the 434MHz Transmitter module

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India’s Second Solar Powered Train

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In India there are 2 solar powered trains that were transformed from normal passenger trains into ones equipped with solar panels. Also they replaced the normal light bulbs with LEDs which has an illumination level of 42 lux compared to previously illumination level which was 20 lux, when it was a normal train.

The train has been installed with solar-powered sockets, which will enable recharging of mobiles and cameras during their journey. The overall cost of converting the train into a solar power unit was around Rs 225,000, that is equal to $4500.
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The Graphene Supercapacitor Revolution!

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You wouldn’t believe what they have discovered while making some experiments with the graphene – a Nobel-prize winning supermaterial. They were trying to produce high-quality sheets of graphene using a regular DVD-Burner and they succeeded, but the real surprise came when a researcher in Richard Kaner‘s lab wired a small square of their high quality carbon sheets up to a LED and it lit!

The graphene “supercapacitor” was charged only for 3 seconds but the LED run for over 5 minutes! I think this is very important and the world will soon change and the well-known batteries will soon be changed for good with these type of graphene supercapacitors which have a high energy storage and charges and discharges 1200 times faster than a battery.
Imagine the future where we will charge our devices in seconds, where electric cars will be everywhere and you can charge their batteries in minutes, even faster! Not to mention that the graphene supercapacitor is ecological.
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This infrared transmitter use PWM (pulse width modulation).
The transmitter is equiped with LM567, tone decoder circuit. Audio signal ( at least 50mVvv ) is amplified with T1 and then it is used to modulate IC1. Infrared transmitter frequency is adjusted with P2 between 25 and 40KHz.
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LM567, NE567, SE567 Datasheet

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The LM567, NE567 and SE567 are general purpose tone decoders designed to provide a saturated transistor switch to ground when an input signal is present within the passband. The circuit consists of an I and Q detector driven by a voltage controlled oscillator which determines the center frequency of the decoder. External components are used to independently set center frequency, bandwidth and output delay.
567 Applications
  • Touch Tone Decoding
  • Precision Oscillator
  • Frequency Monitoring and Control
  • Wide Band FSK Demodulation
  • Ultrasonic Controls
  • Carrier Current Remote Controls
  • Communications Paging Decoders
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Low Voltage Audio Amplifier

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This experimental (3) transistor class A audio power amplifier delivers 25mW into an 8Ω load, or 50mW into a 4Ω load using only a 1.5V power source. At such low voltages, there are many issues to consider and much to learn. To the best of my knowledge the following information is new to the world.
Theoretical minimum vs. practical minimum voltage
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Hearing Aids Circuit

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The medium-power amplifier section is wired around popular audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for portable low-power applications, is readily available in 8-pin mini DIP package. Here the IC is wired in bridge configuration to drive the 32-ohm general-purpose monophonic earphone.
The audio output of this hearing aid circuit is 10 to 15 mW and the quiescent current drain is below 1 mA. The circuit can be easily assembled on a veroboard. For easy assembling and maintenance, use an 8-pin DIP IC socket for TDA2822M.

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Infrared Alarm Barrier Circuit

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This infrared alarm barrier can be used to detect persons passing through doorways, corridors and small gates. The transmitter emits a beam of infrared light which is invisible to the human eye. The buzzer at the output of the receiver is activated when the light beam is interrupted by a person passing through it.

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Wireless Light Switch Circuit

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You may use this wireless light switch instead of physical contact with switches which may be dangerous if there is any shorting.
The wireless light switch circuit described here requires no physical contact for operating the appliance. You just need to move your hand between the infrared LED (IR LED1) and the phototransistor (T1). The infrared rays transmitted by IR LED1 is detected by the phototransistor to activate the hidden lock, flush system, hand dryer or else.

This wireless light switch is very stable and sensitive compared to other AC appliance control circuits. It is simple, compact and cheap. Current consumption is low in milliamperes. The circuit is built around an IC CA3140, IRLED1, phototransistor and other discrete components.
The working of the circuit is simple. In order to switch on the appliance, you simply interrupt the infrared rays falling on the phototransistor through your hand. During the interruption, the appliance remains on through the relay. When you remove your hand from the infrared beam, the appliance turns off through the relay.

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Mobile Solar Charger

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Here is an ideal mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. It can replenish cell phone battery three or four times in places where AC power is not available.

Most of the Mobile phone batteries are rated at 3.6 V/500 mA. A single pen torch cell can provide 1.5 volts and 1.5 Amps current. So if four pen cells are connected serially, it will form a battery pack with 6 volt and 1.5 Amps current. When power is applied to the circuit through S1, transistor T1 conducts and Green LED lights.When T1 conducts T2 also conducts since its base becomes negative. Charging current flows from the collector of T1. To reduce the charging voltage to 4.7 volts, Zener diode ZD is used. The output gives 20 mA current for slow charging. If more current is required for fast charging, reduce the value of R4 to 47 ohms so that 80 mA current will be available. Points A and B are used to connect the charger with the mobile phone. Use suitable pins for this and connect with correct polarity.

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Launching the brand-new GaN-template product from Hitachi Cable

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Hitachi Cable, Ltd. hereby announces that it has developed a new mass-production technology for GaN-templates (Fig. 1), in which a high-quality gallium nitride (GaN) single-crystal thin film is grown on a sapphire substrate, and it will start selling these templates.

Using this product as a base substrate for an epitaxial wafer for white LEDs (hereinafter referred to as "epiwafer for white LED epiwafers") makes it possible to drastically improve productivity of white LED epiwafers and the LED properties. Therefore, this product is expected to become an effective solution to improve the position of white LED manufacturers in the industry, where there is severe competition.

The demand for white LEDs is rapidly expanding and they have come to be used in backlight unit in liquid crystal displays (LCDs) and ordinary lighting devices in recent years thanks to their energy efficiency and long service life. The structure of an white LED epiwafer consists of a thin active layer and a p-type GaN layer with a total thickness of about 1µm over an n-type GaN layer with a thickness of about 10µm, grown on a sapphire substrate (Fig. 2). All these crystal layers are produced by the MOVPE method *1 in ordinary manufacturing processes. The MOVPE method is suitable for growing active layers which require atomic-level control of the film thickness. Meanwhile, a disadvantage of this method is that it takes a long time to grow a high-quality and thick n-type GaN layer. White LED epiwafers can be grown about once or twice a day at the most, and thus there is a need for a high-efficiency production method.
Fig. 1 Cross-section of GaN-template                          Fig. 2 Cross-section of the epiwafer for white LEDs

To solve this problem, Hitachi Cable developed a GaN-template used as a base substrate for growth in the MOVPE method.

The GaN template consists of an n-type GaN layer grown on a sapphire substrate. Using a GaN-template means LED manufacturers do not need to grow an n-type GaN buffer layer and this reduces the time required for growth by about half compared with conventional methods. The GaN-templates of Hitachi Cable are also suitable for high-output LEDs which require large currents because they allow both low resistance and high crystal formation.


Hitachi Cable has developed single-crystal free-standing GaN substrates used for blue-violet lasers and developed unique HVPE-growth *2 technology and machines for mass-production of GaN substreates. Based on this technology, Hitachi Cable developed new high-efficiency production technology and machines for mass-production of high-quality GaN-templates. The main characteristics of the GaN-template are as follows.

Main characteristics of GaN-template
  • High crystal quality and high surface quality based on growth technology established in the development of free-standing GaN substrates
  • Low resistance n-type GaN buffer which is suitable for high-output wafers and bonding-type LEDs*3
  • Templates on flat-surface sapphire substrates and various types of PSS *4 are available
  • Wafers with 2 to 6 inches in diameters are available(8-inch version is now planned for development)

With this new GaN-template added to the lineup of GaN substrates and GaN epiwafers that it has been selling, Hitachi Cable will strengthen and expand its GaN product group and offer compound semiconductor products which respond to the various needs of clients.

Panel exhibits of GaN-templates will be presented at an exhibition hosted by CS Mantech (an international conference for manufacturing technology of compound semiconductor) to be held in New Orleans in the United States from May 13 to 16.

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Continuous monitoring of UV exposur

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UV lamps are used to cure coatings and adhesives in many industrial manufacturing processes. And special sensors are used to measure the intensity of the UV light applied to these surfaces. But because these sensors age too quickly, they can only be used to record intermittent measurements. Fraunhofer researchers have developed a new generation of sensors capable of continuously monitoring UV intensity. These devices will be presented for the fi rst time at the Sensor + Test trade show in Nuremberg, from May 14 to 16 (Hall 12, Booth 537).
“UV exposure” is a term that tends to ring alarm bells, as most people associate it with unpleasant consequences such as sunburn and the risk of skin cancer. But ultraviolet (UV) light can also be benefi cial, or indeed essential: the human body needs it to produce vitamin D. Industry, too, makes use of UV light, for example to cure adhesives or the coatings applied to food packaging, and also to disinfect water. On the other hand, surfaces can be damaged if they are exposed to too much UV light, and poorly regulated UV lamps also waste energy and generate excessive amounts of ozone. UV sensors are therefore used to optimize light intensity.

Usually these sensors are made of silicon or silicon carbide. The problem with silicon sensors is that they only deliver useful results if visible light is excluded from the measurement by external fi lters. Unfortunately, the fi lters used are very expensive and not particularly resistant to ultraviolet light. So to reduce ageing, measurements can only be taken intermittently, as snapshots. Silicon carbide sensors have the advantage of being able to withstand longer exposure to UV light, but they only operate in a narrow spectral band. In the majority of industrial curing processes, it is the longer wavelengths that are of interest – precisely the area in which these sensors are least accurate.

Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg have now developed a new UV sensor in collaboration with colleagues at the Fraunhofer Institutes for Manufacturing Technology and Advanced Materials IFAM, for Optronics, System Technologies and Image Exploitation IOSB, for Silicon Technology ISIT and for Physical Measurement Techniques IPM. “Our sensor is based on aluminum gallium nitride technology and can withstand continuous exposure to UV light without damage,” says IAF project manager Dr. Susanne Kopta. “This enables it to be used not only for intermittent snapshots but also for permanent inline monitoring.” A sapphire wafer serves as the substrate for the sensors. The researchers apply epitaxial growth to deposit layers of the active material onto the substrate, in other words the layers have a crystalline structure.

Sensor for high UV intensities
The particular strength of this novel sensor is its suitability for applications involving very high UV intensities – and for tasks that require the monitoring of specifi c spectral ranges. This is due to the fact that the detectors can be set to operate in two different ways. The fi rst option is to defi ne a maximum wavelength threshold. In this case the sensor detects all UV light emitted at wavelengths below the set limit. The alternative is to defi ne two wavelength thresholds, thus “cutting out” certain parts of the spectrum. “The narrowest range we have been able to achieve is a separation of 20 nanometers,” reports Kopta. This makes it possible to manufacture one sensor for UV-A, another for UV-B, and a third for UV-C. But how do the researchers set the wavelengths to be detected by the sensor? Kopta replies: “We do this by varying the ratio of gallium to aluminum in one of the aluminum gallium nitride layers.”

Defining this ratio is one of the challenges that the researchers are working on at present. Another challenge is growing the aluminum gallium nitride crystal – the heart of the sensor – in such a way that it is free of structural defects and impurities. Failure to do so would result in unreliable measurements because different areas of the sensor would absorb light at different wavelengths. “The hardest part is dealing with the wide range of parameters that affect the manufacture of thin crystal fi lms, which demands a great deal of experience,” explains Kopta.

A few demonstration models have already been produced. In the next stage of the project, the researchers aim to optimize crystal growth and obtain more sharply defi ned wavelength limits. They are also investigating the component durability, with very encouraging results so far. “Initial tests have confirmed that the sensors are capable of operating for 1000 hours under high UV exposure without suffering any damage,” reports Kopta.

UV sensors as team players
The UV sensors are not only excellent “solo artists”; they are also great team players.By placing more than 100 detectors side by side in a strip, you obtain a UV camera. This device can be used to monitor plasma deposition processes, such as those employed to coat solar cells with an antirefl ective fi lm. The sensor strip can also serve as a spectrometer. In this case, the UV light is fi rst passed through a diffraction grating which splits the light into its various spectral components, like the colors of a rainbow. Each individual sensor detects a specifi c wavelength and provides information on the intensity of light at that wavelength. This would be a good way of conducting ageing tests on the mercury lamps commonly used for water disinfection or UV curing. Does the lamp still emit light of the desired intensity throughout the entire spectrum, or are certain wavelengths weaker than they ought to be?

The researchers will be presenting the novel UV sensors for different wavelengths at the Sensor + Test trade show in Nuremberg from May 14 to 16 (Hall 12, Booth 537)
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The printed & flexible electronics market will reach ~$950M in 2020 with a 27% CAGR in market value, estimates Yole Développement

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Yole Développement announces its Flexible Applications Based on Printed Electronics Technologies 2013 report. Yole Développement’s report provides up-to-date market forecast 2013-2020, roadmaps and timelines for printed, flexible, and printed & flexible applications. Also, it analyses the function vs. flexibility, current technical & economic challenges, manufacturing process and focuses on polytronics.
Technical challenges are close to being overcome to reach US$1B market by 2020
Today flexible & printed electronics create a lot of hope. And a supply chain is being created to support an industrial infrastructure. In its report, Yole Développement has identified and tracked the five main functionalities of flexible & printed electronics: displaying, sensing, lighting, energy generating and substrates. The different degrees of freedom in flexibility that can be obtained can be divided into:
• Conformable substrate: the flexible substrate will be shaped in a definitive way after processing
• “Bendable” substrate: they can be rolled and bent many times (even if we consider it will not be a key feature coming from customer needs)
• “Unused” flexibility: in the end, the flexibility is not an added value to the customer
Yole Développement’s analysts believe some applications will be more likely than other to be successful – for example, bendable applications will undergo tough stress during use and technological challenges will be hard to overcome. The report shows the distinction between the functions (displaying, lighting, energy conversion, sensing & substrates) and the seek flexibility “degree of freedom”. Yole Développement does not make the distinction in its report between organic and inorganic substrates as semiconductors can also be used as flexible substrates.
However, the team of analysts believe over the next several years, the number of applications using printing processes for flexible electronics will grow.
We estimate the printed & flexible electronics market will grow from ~ $176M in 2013 to ~ $950M in 2020 with a 27% CAGR in market value. Printed OLED displays for large size (TVs) are likely to become the largest market,” explains Dr Eric Mounier, Senior Analyst, MEMS Devices & Technologies, at Yole Développement. For OLED lighting, Yole Développement believes it will grow but remain a niche market for automotive and/ or office lighting. For PV, the market demand by 2020 will remain very low compared to the demand for rigid PV, largely below 1% of the global market demand by 2020. Sensor, smart system & polytronic applications will include sensors, touchless / touch screens, RF ID applications.
A wide, exciting range of new applications
Printed & flexible electronics is a new exiting technology with large potential market expectations. Indeed, as semiconductors move to the very small with 22nm critical dimension, printed electronics moves to the other end of the spectrum with its own material, equipment, process challenges and supply chain. Printed electronics will not kill semiconductor electronics as it will not be a replacement for CMOS silicon. However, it will create new industry segments and new classes of applications with unique features, benefits and costs that cannot be addressed with conventional semiconductor electronics.
For example, Yole Développement’s analysts believe printing technologies will also allow additional properties such as flexibility. Originally, the general vision for printed electronics was the possibility to print low cost electronic components on any substrate. It was supposed to allow low cost, low efficiency, large volume electronics manufacturing, and it was supposed to create a large multiplicity of applications. Flexible electronics appeared quite soon after envisaging printability. Such devices were supposed to allow new applications directly linked to flexibility.
Moreover, the coming of polytronic technologies is a disruptive approach that could change the way printed & flexible electronic devices will be manufactured. It can be considered a new alternative to the “More Moore” approach where Si ICs, thin films, micro batteries, displays etc. … will be embedded in a flexible substrate. The global interest in polytronics is born from the difficulties faced by the flexible & printed electronics industry. It is an alternate way to come to similar results while trying to avoid some of the main challenges.

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Engineers work to better monitor missile health

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The Aviation and Missile Research Development and Engineering Center is leveraging micro-electro-mechanical systems research in a new application to detect potentially damaging vibrations encountered by missiles during handling, transport and operation.

Stephen Marotta, Engineering Directorate project principal investigator, said MEMS research has been ongoing at AMRDEC for many years and many different applications have been successfully transitioned from the lab to the Soldier in the field.

In an effort to improve missile health monitoring, Marotta began collaborating with Mohan Sanghadasa, from AMRDEC’s Weapons Development and Integration Directorate, and Stephen Horowitz, an engineer with Ducommun Miltec.

The AMRDEC team is using technology, both current and in-development, to design a new MEMS sensor that will offer several benefits over current missile health monitoring systems.

We’ve spent a number of years developing acoustic sensors, microphones based on piezoelectric materials,Horowitz said, “and there’s not a huge difference between designing a microphone and designing a vibration sensor and accelerometers. It’s a different structure, a different geometry, but we use the same fabrication processes to create them. On our first generation sensor, we used the same materials even.
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InvenSense® introduces world’s smallest dual-axis gyroscopes for optical image stabilization in smartphone

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InvenSense, Inc. (NYSE: INVN), the leading provider of MotionTracking™ devices, announced the IDG-2030 and IXZ-2030 dual-axis Optical Image Stabilization (OIS) gyroscopes.

OIS eliminates the effects of hand jitter to achieve blur free images and jitter free HD video. The benefits of OIS are most evident in low light conditions where longer exposure times are required. The IDG-2030 expands the dominant position established by the IDG-2021 in the OIS market. At 2.3x2.3x0.65mm, the IDG-2030 sets a new standard for size, profile, and power consumption. The IDG-2030, enabled by InvenSense’s patented technology platform, provides a 41% foot print reduction, 28% lower profile, and 50% lower power than the nearest competitor.

The first wave of OIS enabled smartphones has already hit the market with image quality rivaling high performance digital cameras,” said Ali Foughi, Vice President of Marketing and Business Development at InvenSense. “As the leader in this market, we are enabling the rapid adoption of OIS in smartphones by providing the world’s lowest profile and lowest power OIS gyroscopes. According to 3rd party estimates, the smartphone market will exceed 1.3 billion units in 2016, with the OIS attach rate reaching 60% to 80%. We are bringing the DSLR experience to smartphone consumers and InvenSense is positioned to achieve significant market share.
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In a paper to be published in an upcoming issue of Energy & Environmental Science (now available online), researchers at the U.S. Department of Energy's Brookhaven National Laboratory describe details of a low-cost, stable, effective catalyst that could replace costly platinum in the production of hydrogen.
  • New material is a promising alternative to costly platinum catalyst
The catalyst, made from renewable soybeans and abundant molybdenum metal, produces hydrogen in an environmentally friendly, cost-effective manner, potentially increasing the use of this clean energy source.

The project branches off from the Brookhaven group's research into using sunlight to develop alternative fuels. Their ultimate goal is to find ways to use solar energy—either directly or via electricity generated by solar cells—to convert the end products of hydrocarbon combustion, water and carbon dioxide, back into a carbon-based fuel. Dubbed "artificial photosynthesis," this process mimics how plants convert those same ingredients to energy in the form of sugars. One key step is splitting water, or water electrolysis.

This form of hydrogen production could help the scientists achieve their ultimate goal.

"A very promising route to making a carbon-containing fuel is to hydrogenate carbon dioxide (or carbon monoxide) using solar-produced hydrogen," said Fujita, who leads the artificial photosynthesis group in the Brookhaven Chemistry Department.  

But with platinum as the main ingredient in the most effective water-splitting catalysts, the process is currently too costly to be economically viable.

Comsewogue High School students Shweta and Shilpa Iyer entered the lab as the search for a cost-effective replacement was on.
Fig 1: Splitting hydrogen from water: This illustration depicts the synthesis of a new hydrogen-production catalyst from soybean proteins and ammonium molybdate. Mixing and heating the ingredients leads to a solid-state reaction and the formation of nanostructured molybdenum carbide and molybdenum nitride crystals. The hybrid material effectively catalyzes the conversion of liquid water to hydrogen gas while remaining stable in an acidic environment.

The Brookhaven team had already identified some promising leads with experiments demonstrating the potential effectiveness of low-cost molybdenum paired with carbon, as well as the use of nitrogen to confer some resistance to the corrosive, acidic environment required in proton exchange membrane water electrolysis cells. But these two approaches had not yet been tried together.

To make the catalyst the team ground the soybeans into a powder, mixed the powder with ammonium molybdate in water, then dried and heated the samples in the presence of inert argon gas. "A subsequent high temperature treatment (carburization) induced a reaction between molybdenum and the carbon and nitrogen components of the soybeans to produce molybdenum carbides and molybdenum nitrides," Chen explained. "The process is simple, economical, and environmentally friendly."

Electrochemical tests of the separate ingredients showed that molybdenum carbide is effective for converting H2O to H2, but not stable in acidic solution, while molybdenum nitride is corrosion-resistant but not efficient for hydrogen production. A nanostructured hybrid of these two materials, however, remained active and stable even after 500 hours of testing in a highly acidic environment.

Structural and chemical studies of the new catalyst conducted at Brookhaven's National Synchrotron Light Source (NSLS) and the Center for Functional Nanomaterials (CFN) are also reported in the paper, and provide further details underlying the high performance of this new catalyst.

The scientists also tested the MoSoy catalyst anchored on sheets of graphene—an approach that has proven effective for enhancing catalyst performance in electrochemical devices such as batteries, supercapacitors, fuel cells, and water electrolyzers. Using a high-resolution transmission microscope in Brookhven's Condensed Matter Physics and Materials Science Department, the scientists were able to observe the anchored MoSoy nanocrystals on 2D graphene sheets.

The graphene-anchored MoSoy catalyst surpassed the performance of pure platinum metal. Though not quite as active as commercially available platinum catalysts, the high performance of graphene-anchored MoSoy was extremely encouraging to the scientific team.

The scientists are conducting additional studies to gain a deeper understanding of the nature of the interaction at the catalyst-graphene interface, and exploring ways to further improve its performance.

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Novel technique to observe nanoparticles in a liquid environment

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The macroscopic effects of certain nanoparticles on human health have long been clear to the naked eye. What scientists have lacked is the ability to see the detailed movements of individual particles that give rise to those effects.

  • This technique will allow, for the first time, the imaging of nanoscale processes, such as the engulfment of nanoparticles into cells.
In a recently published study, scientists at the Virginia Tech Carilion Research Institute invented a technique for imaging nanoparticle dynamics with atomic resolution as these dynamics occur in a liquid environment. The results will allow, for the first time, the imaging of nanoscale processes, such as the engulfment of nanoparticles into cells.

Nanoparticles are made of many materials and come in different shapes and sizes. In the new study, Kelly, an assistant professor at the Virginia Tech Carilion Research Institute, and her colleagues chose to make rod-shaped gold nanoparticles the stars of their new molecular movies. These nanoparticles, roughly the size of a virus, are used to treat various forms of cancer. Once injected, they accumulate in solid tumors. Infrared radiation is then used to heat them and destroy nearby cancerous cells.

To take an up-close look at the gold nanoparticles in action, the researchers made a vacuum-tight microfluidic chamber by pressing two silicon-nitride semiconductor chips together with a 150-nanometer spacer in between. The microchips contained transparent windows so the beam from a transmission electron microscope could pass through to create an atomic-scale image.

Using the new technique, the scientists created two types of visualizations. The first included pictures of individual nanoparticles’ atomic structures at 100,000-times magnification – the highest resolution images ever taken of nanoparticles in a liquid environment.

The second visualization was a movie captured at 23,000-times magnification that revealed the movements of a group of nanoparticles reacting to an electron beam, which mimics the effects of the infrared radiation used in cancer therapies.

In the movie, the gold nanoparticles can be seen surfing nanoscale tidal waves.

The team is also testing the resolution of the microfluidic system with other reagents and materials, bringing researchers one step closer to viewing live biological mechanisms in action at the highest levels of resolution possible.
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Improving materials that convert heat to electricity and vice-versa

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Thermoelectric materials can be used to turn waste heat into electricity or to provide refrigeration without any liquid coolants, and a research team from the University of Michigan has found a way to nearly double the efficiency of a particular class of them that's made with organic semiconductors.

  • Improved properties of PEDOT:PSS for thermoelectric applications
Organic semiconductors are carbon-rich compounds that are relatively cheap, abundant, lightweight and tough. But they haven't traditionally been considered candidate thermoelectric materials because they have been inefficient in carrying out the essential heat-to-electricity conversion process.

Most efficient thermoelectric materials are made of relatively rare inorganic semiconductors such as bismuth, tellurium and selenium that are expensive, brittle and often toxic. Still, they manage to convert heat into electricity more than four times as efficiently as the organic semiconductors created to date.

This greater efficiency is reflected in a metric known by researchers as the thermoelectric "figure of merit." This metric is approximately 1 near room temperature for state-of-the-art inorganic thermoelectric materials, but only 0.25 for organic semiconductors.

U-M researchers improved upon the state-of-the-art in organic semiconductors by nearly 70 percent, achieving a figure-of-merit of 0.42 in a compound known as PEDOT:PSS.

PEDOT:PSS is a mixture of two polymers: the conjugated polymer PEDOT and the polyelectrolyte PSS. It has previously been used as a transparent electrode for devices such as organic LEDs and solar cells, as well as an antistatic agent for materials such as photographic films.

One of the ways scientists and engineers increase a material's capacity for conducting electricity is to add impurities to it in a process known as doping. When these added ingredients, called dopants, bond to the host material, they give it an electrical carrier. Each of these additional carriers enhances the material's electrical conductivity.

In PEDOT doped by PSS, however, only small fraction of the PSS molecules actually bond to the host PEDOT; the rest of the PSS molecules do not become ionized and are inactive. The researchers found that these excess PSS molecules dramatically inhibit both the electrical conductivity and thermoelectric performance of the material.

To improve its thermoelectric efficiency, the researchers restructured the material at the nanoscale. Pipe and his team figured out how to use certain solvents to remove some of these non-ionized PSS dopant molecules from the mixture, leading to large increases in both the electrical conductivity and the thermoelectric energy conversion efficiency.

This particular organic thermoelectric material would be effective at temperatures up to about 250 degrees Fahrenheit.
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 The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the informal notion of "thickness". For example, honey has a higher viscosity than water . Viscosity is due to friction between neighboring parcels of the fluid that are moving at different velocities. When fluid is forced through a tube, the fluid generally moves faster near the axis and very little near the walls, therefore some stress (such as a pressure difference between the two ends of the tube) is needed to overcome the friction between layers and keep the fluid moving. For the same velocity pattern, the stress is proportional to the fluid's viscosity. A liquid's viscosity also depends on the size and shape of its particles and the attractions between the particles
A fluid that has no resistance to shear stress is known as an ideal fluid or inviscid fluid. In the real world, zero viscosity is observed only at very low temperatures, in superfluids. Otherwise all fluids have positive viscosity. If the viscosity is very high, such as in pitch, the fluid will seem to be a solid in the short term. In common usage, a liquid whose viscosity is less than that of water is known as a mobile liquid, while a substance with a viscosity substantially greater than water is simply called a viscous liquid.

types --

Shear viscosity

The shear viscosity of a fluid expresses its resistance to shearing flows, where adjacent layers move parallel to each other with different speeds. It can be defined through the idealized situation known as a Couette flow, where a layer of fluid is trapped between two horizontal plates, one fixed and one moving horizontally at constant speed u. (The plates are assumed to be very large, so that one need not consider what happens near their edges.)

The magnitude F of this force is found to be proportional to the speed u and the area A of each plate, and inversely proportional to their separation y. That is,
 F=\mu A \frac{u}{y}
The proportionality factor μ in this formula is the viscosity (specifically, the dynamic viscosity) of the fluid.
The ratio u/y is called the rate of shear deformation or shear velocity, and is the derivative of the fluid speed in the direction perpendicular to the plates. Isaac Newton expressed the viscous forces by the differential equation
\tau=\mu \frac{\partial u}{\partial y}
where \tau = F/A and {\partial u}/{\partial y} is the local shear velocity. This formula assumes that the flow is moving along parallel lines and the y axis, perpendicular to the flow, points in the direction of maximum shear velocity. This equation can be used where the velocity does not vary linearly with y, such as in fluid flowing through a pipe.

Kinematic viscosity

The kinematic viscosity is the dynamic viscosity μ divided by the density of the fluid ρ. It is usually denoted by the Greek letter nu (ν). It is a convenient concept when analyzing the Reynolds number, that expresses the ratio of the inertial forces to the viscous forces:
Re = \frac{\rho u D}{\mu} = \frac{uD}{\nu}

Bulk viscosity

When a compressible fluid is compressed or expanded evenly, without shear, it may still exhibit a form of internal friction that resists its flow. These forces are related to the rate of compression or expansion by a factor σ, called the volume viscosity, bulk viscosity or second viscosity
The bulk viscosity is important only when the fluid is being rapidly compressed or expanded, such as in sound and shock waves. Bulk viscosity explains the loss of energy in those waves, as described by Stokes' law of sound attenuation.
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Embeded Server

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Miniature embedded device server is a complete internet server built into an ethernet (RJ-45) jack.
A device embedded with a fully integrated miniature device server can provide the internet data communication capability such that
  • The user can access the device setting through a standard internet browser.
  • The manufacture can upgrade the system software / firmware of the device via the internet.
  • The technical support personnel can do remote configuration, monitoring, and troubleshooting, including real-time device performance notification without in-house service visit.
  • A dedicated co-processor, if available in the device, can be used to optimize network activities, permitting the host microprocessor to function at maximum efficiency.
For example, if the miniature device server is embedded in every house appliance, one can easily do the following:
  • Schedule the recording time of VCR, pay-per-view or video-on-demand programs on the more user friendly internet browser.
  • Coordinate the coffee maker and toaster with the alarm clock in the morning.
  • Coordinate the air conditioner, water heater, oven, bread maker, and/or rice cooker with his/her office computer that takes effect when he/she checks out from office in the afternoon.
  • No need to change clocks between day-light-saving and standard time (in fact, all clocks will be synchronized and always report the accurate time).
  • Automatically inform the technician or plumber for maintenance or repair, when needed.
In short, the miniature embedded device server makes devices "network enabled." Once devices are connected to the internet, it is a whole new world.
Common Specifications  
Common specifications for commercially available Miniature Embedded Device Servers are listed below:
  Network Interface: RJ45 Ethernet 10BASE-T or 100BASE-TX (auto-sensing)
  Compatibility (Ethernet): Version 2.0/IEEE 802.3
  Storage capacity: 384 ~ 512 KB
  Weight: 9.6 grams (0.34 oz)
  Material: Metal shell, thermoplastic case
  Temperature: Operating -40°C to +85°C (-40°F to 185°F)
Storage -40°C to +85°C (-40°F to 185°F)
  Relative Humidity: 5% to 95% non-condensing
  Shock/Vibration: Non-operational shock: 500 g's
Non-operational vibration: 20 g's
  Supply Voltage: 3.3 V ±5%
  Input Voltage: Low level 0 ~ 0.8 V
High Level 2.0 V ~ Supply Voltage
  Output Voltage: Low level up to0.4 V
High Level no less than 2.4 V
  Leakage Current: Input or Output 10 µA
  Typical Supply Current: Idle 130mA
10BASE-T activity 140mA
100BASE-T activity 210mA

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NCAP Display

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Unlike most LCDs which are difficult to read in bright sunlight, the NCAPTM Plastic Liquid Crystal Display (Polymeric LCD) actually gets easier to read in brighter light (just like a piece of paper). For informational displays with many separately controlled segments (such as a digital clock), each part of the liquid crystal panel can selectively be turned 'on.' Furthermore, the amount of translucency is proportional to the voltage applied.

The heart of the NCAPTM technology is the liquid crystal cell. Normally this cell is black, allowing almost no light through. But when a current passes through it, instantly it turns transparent. Behind this liquid crystal cell is a colored reflective pattern. When the cell turns transparent, the colored print beneath shows through.
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Unlike most LCDs which are difficult to read in bright sunlight, the NCAPTM Plastic Liquid Crystal Display (Polymeric LCD) actually gets easier to read in brighter light (just like a piece of paper).
For informational displays with many separately controlled segments (such as a digital clock), each part of the liquid crystal panel can selectively be turned 'on.' Furthermore, the amount of translucency is proportional to the voltage applied.
Further Information  
The heart of the NCAPTM technology is the liquid crystal cell. Normally this cell is black, allowing almost no light through. But when a current passes through it, instantly it turns transparent. Behind this liquid crystal cell is a colored reflective pattern. When the cell turns transparent, the colored print beneath shows through.
NCAPTM plastic displays can be directly applied to where clear, bright displays / control panels are needed such as
  • Information displays
  • Automobiles
  • Gaming machines
  • Household appliances (e.g., microwave oven)
  • Biomedical instruments or other instrumentation
  • Point of sale
Some potential applications for applying the NCAPTM LCD cell include
  • Exhibit displays, billboards, schedule boards
  • Ski goggles, sunglasses
  • Automotive windows, portable sun shade / umbrella
  • Telephone booth, changing room, office window / surgery room, hide home entertainment center
  • Peek through oven window, transparent drawers / kitchen cabinets for easy searching
Common Specifications  
Common specifications for commercially available NCAPTM plastic displays are listed below:
  Dimension: Up to 39 inch x 1000 ft (LDC cell itself)
Up to 22 inch x 15 inch (NCAPTM Display)
  Color: Available in warm yellow, yellow, green, blue, white, orange, and red. However, There are no technical limitations restricting particular colors.
  Operating Temperature: -20 ~ 85 °C
  Storage Temperature: -50 ~ 85 °C
  Voltage: 24 ±1.2 V
  Frequency: 50 / 60 Hz (25 ~ 120 Hz)
  DC Offset: ±350 mVdc
  Optical Performance: Color difference (1976 CIE UCS):
Warm yellow = 73; Red = 106;
  Response Time: Time on at 25°C = 6 ms; Time off at 25°C = 16 ms
Time on at 0°C = 42 ms; Time off at 0°C = 84 ms

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