Monthly Archives: May 2014

The portable LED work light has an aluminum frame

Larson Electronics has launched a new portable LED work light rated at 150 Watts. It is mounted within an adjustable aluminum frame. Christened by the company as Explosion Proof, EPL-TFM-150LED-RT-100-2023 LED Light, It is rated for Class 2 Division 1-2 and Class 1 Division 1-2 in Groups C & D. The LED work light can generate light output of 12,000 Lumens for which it needs to draw a power of 150 watts only. The light head is 16 inches by 14 inches, mounted on a tubular frame made of light aluminum and has an easy to use handle provided at the top. The light covers an area of 9000 square feet.

The LED light produces a brilliant pattern and is most suitable for hazardous environments and enclosed areas. The light has a very wide range of application in a number of locations such as where there are ample amounts of dust, flammable gases and vapors prevalent. The LED light fixture is made of a 16 inches square head and there is a provision for 90-degrees adjustment upwards and downwards. The light can be focused and the position can be locked easily by loosening and retightening the two head screws, present on either side of the stand.

One of the main features of this LED light fixture is the provision of LED drivers that help in increasing the operational longevity. This fixture comprises twelve LED boards configured in a series of six banks. Every bank consists of two LED boards each with a specific driver. In case there is a driver failure in a bank, it will stop operating, while all the other banks will continue to function. In the same way, if there is an LED failure, the mating LED continues to function. These features are very helpful to the user in various locations where non-stop working very essential. There is no ballast box for the fixture and consequently there is no need for its replacement as well.

The LED lamp produces light output that has a 6000K color temperature rating. The color-rendering index is 70 and the details are very accurate when this LED light is compared to mercury vapor or high-pressure sodium lamps. Larson Electronics has provided the light with 100 feet long cord (SOOW) terminated in an explosion-proof, 20 A twist-lock plug that can work at either 125V or 250V, according to the needs of the customer. The lamp is T5 rated and is approved by the Design Lights Consortium. Even after it has been used for more than 60,000 hours, the LED light retains 80% of its Lumen capacity, which is much more than any incandescent or fluorescent lamp. With no UV, infrared or CO2 emissions, the light is very safe and is suitable for offshore applications, tank cleaning, oil field maintenance and repairs.

The Explosion Proof, EPL-TFM-150LED-RT-100-2023 LED Light from Larson Electronics is highly efficient and customer friendly. The company provides customer support and warranty for the lamp fixture. As the company is a leader in the LED lamp fixture, the new launch is expected to be a boon for the industry.

Let ezIGBT guide you to the right IGBT

Those who design with IGBTs or Insulated Gate Bipolar Transistors know how difficult it is to select the proper component for a specific application. Several factors have to be carefully weighed simultaneously before you can zero in on the right product. IGBTs are very useful in equipment handling high power, with huge currents passing through them. Failure due to a mismatch involves high expensive replacements. Therefore, engineers have to be very selective when deciding on the right component to use.

For IGBTs, just as for any other semiconductor component, the junction temperature plays a very crucial role in maintaining the proper operation and life of the component. Other parameters that the designer must take into account are the operational voltage, the continuous and maximum currents and the power that the IGBT must handle. While the designer has to rely solely on the information provided to him by the manufacturer, the datasheet of a specific component may be cumbersome and static. From the steady-state figures provided by the manufacturer, it may be difficult to estimate the performance a particular part will play when placed in a circuit.

The website of ezIGBT makes things easier for the designer. It liberates him from the paper data and allows him to model the performance of a part, given specific conditions of junction temperature, operating frequency, applied voltage, current and size of heat sink. The website provides several IGBT models and ezIGBT takes great care to maintain the accuracy of the data.

On the website of ezIGBT, the designer has to supply several operational parameters. These include the on-time voltage across the Collector and Emitter or Vceon, the forward voltage across the copak diode or Vf, on-time voltage or Von, off-time voltage or Voff and the reverse recovery voltage or Err. The website then uses Industry standard techniques to generate equations in two sets: one at 25°C and the other at the highest possible junction temperature.

The equations compute the losses and thermal conditions for the device selected, with the parameters being linearly interpolated between the two temperatures. The datasheet graphs are generally curve-fitted, and expected errors remain less than 10%, which are below the normal variations in manufacturing these devices. At present, ezIGBT is only providing calculations based on “hard switching” type of converters. Calculations for resonant operations are planned for the future.

The website provides three types of tools: Analyze, Compare and Recommend. The Analyze tool helps the designer calculate the power loss at the operating frequency, when the designer specifies the junction temperature and duty cycle. This tool also allows an understanding of how the losses are split between the IGBT and its diode. With this data, the website also estimate the size of the heat sink required.

On the Compare page, you can run the analysis calculated in the previous Analyze section, along with the additional ability to compare the performance of multiple IGBTs.

When you choose your operating conditions, ezIGBT can recommend the parts that will most closely match the requirements of your application. This is done in the Recommend section. At present, the selection depends on the incremental junction temperature rise over the case temperature. Other criteria are expected to be addressed in the future.

Integrated chokes help to reduce power loss

Pulse Electronics Corporation, (San Diego, CA) is a leading electronic component manufacturer. Their new integrated chokes are a special breed, combining common mode and differential mode type into a single mode choke. This new choke integrates the two magnetic components into one, facilitating huge reduction in power loss across the EMI filter part of the power supply. This is made possible by a decrease in resistance of the winding. In addition, Pulse Electronics has considerably reduced the overall space required for the choke. The new integrated choke, the PA4040 from Pulse Electronics, is small with dimensions of 31 x 24.9 mm. The considerable reduction in footprint is to the extent of about 40%, when compared to the combined footprints of equivalent CM and DM components.

The reduced direct current resistance is between 32 and 245 ohms, which results in an overall reduction in power loss. The PA4040 integrated choke offers a number of features. Main among them is it meets a host of safety requirements of several agencies such as UL/CSA/VDE, by allowing 1500 Vrms hi-pot and 3.0 mm in safety distance of creepage and clearance. Further, it may be utilized equally in AC/DC or DC/AC power supplies as it uses a common mode filter and differential mode filter. The main feature is that the current through the filter is less than 3.5 Arms.

The PA4040 from Pulse Electronics finds applications in computing, Datacom, LED lighting drives, solar micro inverters, motor drives and controls. Using PA4040 integrated chokes allows the operational efficiency to go up by 30%. Additionally, because one component replaces two, there is an overall saving in manufacturing cost, time and an increase in throughput. With a 20% saving in cost, PA4040 brings about multiple benefits to the user by way of optimizing performance. Geoff Wildman, product line manager (Power), Pulse Electronics elaborated, “Integrated chokes have been available before, but mainly for custom applications.” He further added, “This catalog release allows for a wider range of customers to enjoy the benefits of integrating the CM and DM chokes.”

A common mode choke blocks or diverts common mode noise in the power supply, while a differential mode choke blocks or diverts the differential mode noise. The PA4040 integrated choke design performs both the functions in a single component and presents a very welcome development with regard to increase in power density, improvement in efficiency and reduction in overall cost. With the wide applications possible, integrated chokes present an exciting development.

Pulse Electronics, the electronic component manufacturer, also provides technical solutions to customers on their specific needs. The company is a pioneer in antennas, magnetics and connectors. At the same time, it has mastered the art of meeting high volume requirements of the customers. It constantly upgrades itself with respect to technical developments and existing customer feedback. The PA4040 integrated choke is engineered to give the customer higher safety along with optimum performance at an affordable cost. Customers acknowledge that the integrated chokes create a new yardstick in efficiency and cost. Pulse Electronics has taken the lead in this respect over others in the field.

How to select the best inductor

A good understanding of the desired in-circuit performance is required for a proper selection of an inductor. Fortunately, this relates to the information available in data sheets supplied by the manufacturer.

Any electronic equipment needs power to operate satisfactorily. Portable instruments invariably use dc-to-dc converters for generating the required voltages from power sources such as batteries. Additionally, as equipment size reduces, so does the need for optimizing inner parts, especially the power conversion solutions; it is no longer possible to stick on to the “one size fits all” approach. For example, manufacturers are producing low profile components, which are proving to be very popular.

Inductance is the primary functional parameter that defines an inductor. This value, calculated by the converter design equations, determines the ability of the inductor to handle the desired output power and control the ripple current in a dc-dc converter. However, specifying the inductance value alone is not sufficient for defining the required inductor. You also need to specify the DCR, SRF, Isat and Imms for a complete specification.

The DCR or the DC resistance of an inductor depends on the length and diameter of the wire used in manufacturing. The power dissipated by the inductor depends on the DCR. Therefore, if the inductor were to be used in an enclosed space, a lower value for the DCR would certainly be an advantage. Please note, resistance offered and hence power dissipated at high frequencies usually depends not on DCR, but on skin effect.

Another important factor is the SRF or the Self-Resonant Frequency of the inductor. At this frequency, an inductor begins to resonate naturally, using the distributed capacitance characteristic of the winding. In a dc-dc converter, SRF might cause unwanted oscillations and lead to instability of the output. The manufacturer specifies the SRF and it depends on the nature of the construction. The designer usually selects an inductor with an SRF that does lies outside the operating frequency range of the application.

Inductors with cores are liable to saturate. When in saturation, the inductance value falls drastically, upsetting the operation of the dc-dc converter. Isat or the Saturation Current, specified by the manufacturer is therefore, an important parameter, which states the amount of current that would cause saturation and subsequently a fall in the inductance value. Designers need to select an inductor that has an Isat value larger than the maximum currents expected in the converter.

Power dissipation in an inductor is dependent on two factors – the DCR and the Irms or the RMS Current flowing through it. Manufacturers specify the maximum rms currents that the inductor can handle causing a specified temperature rise. Therefore, the designer has to select an inductor whose Irms value is larger than the maximum rms currents that the converter is expected to deliver.

Fortunately, dc-dc converters are rather forgiving towards tolerances of inductors. These applications do not require inductors to have extremely tight tolerances to achieve their outputs. Standard tolerances indicated by manufacturers are +/-20%, which most converter designs accept as suitable.

Resurrecting a dead horse? Windows XP

Now that it has been officially announced that there will be no more updates from Microsoft for the workhorse of the industry – Windows XP. The popular and widely used operating system started its life in October 2001. Within the first five years of its availability, officially sold copies outnumbered 400 million. By the time Microsoft withdrew support, in April 2014, the sales figure stood at 1 billion. Add to that the use of another few billion pirated copies all over the world, and you start to get a fairly good estimate of the software’s popularity.

Apart from the popularity, Windows XP figured in several industrially used computers as well, for example, Automatic Teller Machines or ATMs, Point of Sales or POS machines and several types of machine and laboratory instrument controllers. With the withdrawal of active support from Microsoft, the software will not be updated or upgraded, leaving it exposed to exploitation by unscrupulous attackers.

For example, the recent vulnerability exposed in the Internet Explorer, the browser used in almost all Windows OSs, left many wondering about the fate of XP. Fortunately, Microsoft stepped in with the assurance that it will provide a patch for the IE vulnerability for XP. However, Microsoft is unlikely to tackle any further vulnerability discovered subsequently in Windows XP.

However, the situation may not be as hopeless as it sounds. Switching over to Windows 7 or 8 may not be within everyone’s reach, especially when there are several underlying programs working within that depend on Windows XP for their proper operation. Shifting to Windows 7 or 8 might break the functionality of the instrument.

Linux can come to the rescue of such equipment left in the lurch by Microsoft. We are already using Android and Apple phones and computers, both of which are derivatives of the UNIX operating system. Linux is another popular operating system based on UNIX. The best part is you can run any Windows programs in Linux under a virtual mode. The advantage is you do not need to bother about the vulnerabilities of XP, as Linux extends all its inherent security to the operating system used under its virtual mode.

For this, John Martinson has configured a special version of Linux, called the Robolinux. It has a specially formulated virtual mode called the Stealth VM. When you run Windows within this virtual mode, no virus or malware can affect Windows or its data, since the Windows operating system is actually a protected clone and Linux mirrors your data within a secure partition. Additionally, with anything going wrong, you can simply restore the contents of the partition within a few minutes, instead of having to spend hours resurrecting Windows from its CD/DVD.

It is not strictly necessary to run Robolinux for using Stealth VM, as you can run this within any of the existing 500 Linux Operating Systems. If you want to run Windows XP or 7 within your Stealth VM, you simply download the Robolinux Virtual Machine installers. You get the rock-like solidity of UNIX and Linux, including complete protection from viruses and malware when running your coveted Windows XP.

A smartphone built from Raspberry Pi: the PiPhone

You may not be looking for a new cell phone right now, but someone has just managed to transform his Raspberry Pi (RBPi) into a working cell phone. David Hunt has used only off-the-shelf components and put them together for the project. Although it is not as slick as the regular cell phones available in the market, at about $160, David has created a one-off project that certainly has no economics of scale working for it. The best part is all components of the phone can be taken apart at any time, used for some other projects and then reassembled. Can you do that with your regular cell phone?

David has called his cell phone the PiPhone, in honor of the base RBPi that powers it. The other major parts used for making the PiPhone work are a Sim900 GSM/GPRS module and an Adafruit touchscreen interface. The GSM/ GPRS module allows the cell phone to make and receive calls, while the touchscreen provides the user interface. A 2500 mAh LiPo battery powers the entire contraption. The GSM module connects to the RBPi through a UART, while the battery fits in between the TFT screen and the RBPi, allowing the PiPhone to work standalone, without wall warts or dangling wires.

The touchscreen interface has a numeric keypad displayed on the screen. After dialing the required number, you need to touch the phone icon at the bottom to make the call or hang up.

The Sim900 GSM/GPRS is an intelligent module, which oversees the entire communication process of the PiPhone, including sending the standard AT commands to the RBPi for making calls, hanging up and sending text messages or data. Towards the bottom of the PCB is the connector where you can insert your SIM card. Therefore, you can use a regular prepaid SIM card available in the local phone store.

Just below the GSM module, there is an on/off switch and an off-the-shelf standard DC-DC converter. This converts the 3.7V supplied by the battery to the 5V required by the rest of the electronics. Heat dissipation was the only problem that David faced because of sandwiching the RBPi, the TFT, battery and the GPS module together. During development, as all the components were placed apart, they remained cool to the touch even after extended periods of use. However, sandwiching prevents air from circulating within, resulting in the CPU getting a bit warm after switching the unit on for a few minutes.

The GPS card is insulated from the RBPi with a thick foam-core board, allowing no accidental electrical connections between them. David used a couple of cable-ties to hold the different parts together.

Of course, walking into a local phone shop and picking up a normal smartphone would be simpler and cheaper, but that would not be as much fun as making your own. Moreover, as said earlier, you can put the parts to other uses as well, which you cannot do with a standard phone.

David has put up all his code and instructions on the GitHub. There are links available to instructions on installing the TFT.