Category Archives: Guides

Stylus: The Future of the Electronic Pencil?

So far, people have been rather disappointed in using Electronic Pencils (styluses) for the purposes of taking notes on their smartphones. However, a new combination of the MyScript Nebo note-taking app and the Apple Pencil on the iPad Pro seems like a winner. This is really helpful to people who are coming up with ideas at odd times of the day, and have to look for a piece of paper and pencil to jot them down.

The trouble with the paper and pencil approach is eventually every hand-written note has to be laboriously transcribed to the word processor running on a PC. Additionally, a drawing program such as Inkscape or Visio must recreate any hand drawn sketches. Many also have the habit of capturing on paper random thoughts as they crop up in their heads, and later, going back to flesh things out, moving paragraphs around, deleting some, editing others, and adding new material. At the end, there is invariably huge amounts of crossing outs, intermittent notes, and forward/backward pointing arrows.

Presently, those with smartphones, capture their notes by typing things out at a snail’s pace on the soft keyboard, although some are adept at using the same keyboard at lightning speeds. However, the result is nowhere near those achieved with a piece of paper and pencil.

The Apple app store offers two apps free for use—the MyScript Calculator and the MyScript Nebo. You can use the calculator on your iPad by writing your problem using your finger or a simple stylus. Therefore, this becomes a handy app for those always doing simple calculations.

However, the MyScript Nebo app is different. It will not allow you to proceed unless you have an Apple Pencil. Although the Apple Pencil is expensive compared to other styluses available in the market, it is worth spending on this intelligent stylus.
Apple’s Electronic Pencil has a much finer nib than most other styluses do, along with pressure and tilt sensors inside. Once you have mated the stylus with your iPad Pro using Bluetooth, using the stylus becomes a simple affair—just detach the magnetic cap and insert the end of the pencil into the lighting connector on the iPad. A prompt will come up asking if you want to mate this pencil. Simply touch the ok button, and the link is established.

By scanning the signals from the pencil almost 240 times every second with almost zero latency, the iPad Pro achieves results that are close to actual writing with a pen on paper. One can think of this as using crayon or paint brush on paper, depending on the application. The app MyScript Nebo recognizes handwriting very efficiently, and it is much better than other handwriting recognition software available on the market. It also has a spelling correction feature, which works as you write.

A simple scribbling motion is all you need if you wish to delete a letter, sentence, or a paragraph. In the same way, inserting additional material is also possible wherever it is necessary. MyScript Neo is good at deciphering bad handwriting, and recognizing sketches. A simple eraser tool is available to rub out unwanted parts.

What is a QLED?

Recently, Samsung has announced their new TV technology using QLEDs to counter the OLED TVs that LG and others have put on the market. QLED stands for Quantum dot LED, and though Samsung has been using the concept of quantum dots in its TVs for quite some years now, they claim they will be bringing out several flavors of the QLED technology.

According to Samsung, QLEDs are transmissive, as LCDs are, and light goes through several layers to create an image on the surface of the screen. The company claims to be working on the ability of the QLEDs to overcome the challenges currently plaguing the OLEDs.

Although the Q part is currently demanding a premium in the price of Samsung TVs on the market, it will likely decrease in the future. According to Samsung, the QLEDs are bringing several advantages with reference to picture quality, such as higher light output and brighter colors. Samsung claims the light output in highlights is now 2,000 nits, a relative quick loss of peak luminance, and improvement of the delayed ramp-up.

Samsung compares their QLED performance with OLEDs and points out that the new quantum dots offer superior color, providing rich, fully saturated colors even for bright images. However, there is yet no independent testing to substantiate the claims of the company. Moreover, the claims cover only the high-dynamic range as against the standard dynamic range, where the OLED would be a superior performer.

While many observers claim to see better clarity and improved colors in the new TV technology, others fail to notice any difference. You can see QLEDs in Samsung TV model UE55KS9000, and in tablets such as Amazon Kindle Fire HDX 7, and HDX 8.9.

QLEDs contain quantum dots or microscopic molecules between two and 10 nanometers in diameter, which emit their own, differently colored light according to their size, when struck by photons or light particles. In the QLED TVs from Samsung, the dots are restricted to a film, and the LED backlight provides the illumination to light them up. This light then goes through other layers inside the display, which includes an LCD layer, ultimately creating the picture. As the light from the LED source passes through different layers before reaching the screen surface, the process is said to be transmissive.

The advantage of QLEDs is they can emit brighter, more vibrant, and more diverse colors—capable of making HDR content really shine—mainly due to their ability to achieve high peak brightness levels.

Compared to OLED TVs, it is more cost-effective to manufacture quantum dot TVs, which translates to better picture quality at a lower price. However, OLED displays still produce the deepest blacks, which means that OLEDs offer better contrast ratios. Therefore, while OLEDs offer true blacks, quantum dots offer great bright images.

QLED technology replaces the photoluminescent quantum dots with electroluminescent nanoparticles. Therefore, rather than coming from the LED backlight, light now comes directly to the display. Although the process is a lot similar to the light transference process within an OLED TV, within the QLED TV, individual pixels emit the light, thereby combining the best of quantum dots and OLED technology.

Multicolored LEDs Create Secondary Colors

Any student of physics knows mixing two primary color light sources produces a secondary color. For instance, mixing the primary colors red and green creates the secondary color yellow. There are three primary colors—Red, Blue, and Green. This process is easily seen in tricolor and RGB LEDs.

There is a disadvantage in this method. As two primary colors are necessary for generating a secondary color, two LEDs must remain turned on at the same time. Therefore, generating a secondary color means consuming twice the current a primary color requires. In battery powered circuits, the operating current of the LED indicator may be a significant fraction of the total current, and using the same current for generating both primary and secondary colors would be an advantage.

Using a sequencing method can generate balanced secondary colors from RGB, tricolor and bicolor LEDs, while using the operating current of a single LED. The sequencing method offers uniform intensities between the primary and secondary colors, and lower power dissipation. An added advantage of using the sequencing method with bicolor LEDs is keeping a simple pc-board layout with two pins while it produces three colors. Using the sequence method with RGB LEDs produces white light while consuming the operating current of a single LED.

The sequencing method works because it takes advantage of a property of the human eye. This is called persistence of vision, wherein images in the human eye persist for about sixty milliseconds after light from the object ceases to enter the eye. For instance, when a glowing coal is moved about in the dark, the eye sees a continuous red line.

When the human eye sees different primary colors flashed sequentially and quickly from one point, they appear to overlap in time, while the brain interprets the colors to be secondary colors, or, depending on the color components, even white.

Experiments with multiple primary-colored LEDs show that the above flash sequence should repeat every 25 milliseconds or lower, for the eye to treat the effect as a solid secondary color. In fact, the flash rate can go down to one microsecond, before the human eye can detect the degradation of the secondary color. Therefore, any clock source, say a convenient 40 Hz, should be adequate for creating secondary colors.

For the eye to properly see the mixed colors, the primary-color LEDs must be physically very close together, such as on a semiconductor chip. As an added advantage, diffused lenses are better, as this offers a wider viewing angle.

When using bicolor LEDs, the driver has to be bidirectional, as the LEDs are placed back-to-back in the chip. Moreover, currents for the three LEDs may have to be adjusted to achieve color balance between the primary and secondary colors. In addition, color balancing may be required also as LEDs have different intensities and efficiencies as the human eye sees them.

This correction can be done in one of two ways. As each LED has a current limiting resistor in series, the value of these resistors may be tweaked to achieve the necessary differentiation in individual currents. The other option is to keep the same current but tweak the duty cycle.

The Law, Big Data, and Artificial Intelligence

We use a lot of electronic gadgets in our lives, revel in Artificial Intelligence, and welcome the presence of robots. This trend is likely to increase in the future, as we continue to allow them to make many decisions about our lives.

For long, it has been a common practice using computer algorithms for assessing insurance and credit scoring among other things. Often people using these algorithms do not understand the principles involved, and depend on the computer’s decision with no questions asked.

With increasing use of machine learning and predictive modeling becoming more sophisticated in the near future, complex algorithm based decision-making is likely to intrude into every field. As such, expectedly, individuals in the future will have further reduced understanding of the complex web of decision-making they are likely to be subjected to when applying for employment, healthcare, or finance. However, there is also a resistance building up against the above, mainly in the EU, as two Oxford researchers are finding out from their understanding of a law expected to come into force in 2018.

With increasing number of corporations misusing data, the government is mulling the General Data Protection Regulation (GDPR), for imposing severe fines on these corporations. GDPR also contains a clause entitling citizens to have any machine-driven decision processes explained to them.

GDPR also codifies the ‘right to be forgotten’ while regulating the overseas transfer of private data of an EU citizen. Although this has been much talked about, not many are aware of two other clauses within GDPR.

The researchers feel the two clauses may heavily affect rollout of AI and machine learning technology. According to a report by Seth Flaxman of the Department of Statistics at the University of Oxford and Bryce Goodman of the Oxford Internet Institute, the two clauses may even potentially illegalize most of what is already happening involving personal data.

For instance, Article 22 allows individuals to retain the right not to be subject to a decision based solely on automatic processing, as these may produce legal complications concerning them or affect them significantly.

Organizations carrying out this type of activity use several escape clauses. For instance, one clause advocates use of automatic profiling—in theory covering any type of algorithmic or AI-driven profiling—provided they have the explicit consent of the individual. However, this brings up questions whether insurance companies, banks, and other financial institutions will restrict the individual’s application for credit or insurance, simply because they have consented. This can clearly have significant effect on an individual, if the institutes turn him or her down.

According to article 13, the individual has the right to a meaningful explanation of the logic involved. However, organizations often treat the inner working of their AI systems and machine learning a closely guarded secret—even when they are specifically designed to work with the private data of an individual. After January 2018, this may change for organizations intending to apply the algorithms to the data of EU citizens.

This means proponents of the machine learning and AI revolution will need to address certain issues in the near future.

What is a Programmable Logic Controller?

Programmable Logic Controllers (PLCs) are miniature industrial computers. The hardware and software in a PLC are meant to perform control functions. Specifically, a PLC helps in the automation of industrial electromechanical processes. This includes controlling machinery on assembly lines in a factory, rides in an amusement park, or instruments in a food processing industrial establishment.

Most PLCs are designed to facilitate multiple arrangements of analog and digital inputs and outputs. They typically operate with extended temperature range, resistance to impact or vibration, and immunity to electrical noise and disturbances. The basic sections of a PLC usually consist of two sections—the first, the central processing unit (CPU), and the second, an Input/Output (I/0) interface system.

The CPU uses its processor and memory systems to control all system activity. Within the CPU is the micro-controller, memory chips, and other integrated circuits for controlling logic, monitoring, and communications. The CPU may operate in different modes—programmable or run. The programming mode allows the CPU to accept changes to the logic received from another computer. In the run mode, the CPU will execute the program to operate the process.

In the run mode, the CPU will accept input data from connected field devices such as switches, sensors, and more. After processing the data, it will execute or perform the control program stored in its memory system. As the PLC is a dedicated controller, the single program in its memory is processed and executed repeatedly. The scan time, the time taken for one cycle through the program, is typically of the order of one-thousandth of a second. The memory within the system stores the program, while at the same time holding the status of the I/O and provides a means to store values.

Typically, industrial users can fit a wide range of I/O modules to a PLC to accommodate various sensors and output devices. For instance, there are discrete input modules for detecting the presence of objects or events using photoelectric or proximity sensors, limit switches, and pushbuttons. Similarly, with discrete output modules it is possible to control loads such as motors, lights, solenoid valves, mainly to turn them On or Off.

The PLC can be fitted with analog input modules to accept signals generated by process instrumentation such as temperature, pressure, flow, and level transmitters. The modules interpret the signal from their sensors, and present a value within the range determined by the electrical specification of the device.

In the same way, the PLC can use analog outputs to command loads requiring a varying control signal, such as analog flow valves, variable frequency drives, or panel meters. PLCs can also use specialized modules such as serial or Ethernet communications, and high-speed I/O or motion control.

The greatest benefits of a PLC are its ability to change and replicate or repeat the operation of a process while simultaneously collecting and communicating critical information. In the industry, all aspects of a PLC—cost, power consumption, and communication capabilities—are subject to consideration when selecting the right one for the job. Industry automation owes a lot to the PLC or Programmable Logic Controller.

Different Types of Industrial Cables

To wire up different components within electronic gadgets, hook-up and lead wires may be adequate, but the electric industry needs a vast variety of industrial cables to remain connected. Chief among these are power cables to carry high voltages and currents, and cables necessary for industrial automation and process control. Cables may conform to multiple standards such as UL, CSA, and others. Cables often have to transmit power or signal in industrial environments that may harbor the harshest conditions involving physical abuse, high temperature, ozone, chemicals, oil, and other demanding situations.

Challenges and Solutions

With increasing demand from the industry, manufacturers are producing cables for automation and seamless data communication. To support proliferation of mission-critical signal transmission, cable manufacturers offer high quality, high-availability line of industrial cabling and connectivity products.

Seamless Connectivity from the Enterprise to the Sensor

For the most robust and reliable factory networking, manufacturers also offer network switches, I/O modules, and other devices. Users choose their cables from a vast selection of configuration, insulation and jacket materials, shielding options, high-flex capabilities, and other options.

Manufacturers must maintain product consistency for ease of termination and assembly. For instance, precise control of diameters of jacket and insulation along with thickness of concentric wall ensure fast and reliable supplication in automated high-speed equipment.

Shielding

Depending on their use, industrial cables also require highly effective protection from EMI and RFI. There is increasing demand for innovative designs with shielding technology using foil and braid configurations. Manufacturers offer 100% shield coverage improving the protection over a wide range of frequencies. Apart from this, cables also require electrostatic shielding, and sometimes, extra insulation and mechanical strength. Overall, the cable shielding needs to be lightweight, strong, flexible, thin, but extremely effective.

Armoring

For cables requiring maximum physical protection in the harshest of environments, armoring technology is the solution. Armoring offers added advantages such as reduced cost of conduit, easier installation and re-routing, while it provides additional shielding.

Typical armoring of power, instrumentation, and data cables involves interlocking aluminum or steel armor, or continuous corrugated armor of aluminum. Some manufacturers also offer cables with corrugated or smooth protective metal tapes.

Insulation and Jackets

Cable manufacturers offer a large variety of insulation and jacket compounds, often their own formulation. These provide superior performance under different hostile environmental conditions. Cables are typically graded as Class I, II, or III, according to whether they are suitable for hazards differentiated by Division 1 or 2.

For instance, cables suitable for Class I, Division 1 Hazards are used in locations where flammable vapors or gases may exist under normal operating conditions. Cables suitable for Class III, Division 2 Hazards may be used in locations that contain easily ignitable flyings and fibers under abnormal conditions.

Intrinsically Safe

Not all environments need be hostile. Occasionally, under normal or abnormal conditions, equipment and wiring may be incapable of releasing adequate amounts of electrical energy to ignite a susceptible, specific hazardous atmospheric mixture. Manufacturers offer cables with light blue color with approved sealing and separation for use in such situations.

Cable manufacturers offer the most comprehensive line of industrial cabling solutions today. This helps not only for networking on the factory floor or process equipment and devices to their controllers, but also to the control room, and for relaying data between the engineering department, control room, and various office sites or remote manufacturing locations.

What Influences Industrial Connectivity?

In the industry, any component coming in the path of delivering control signals or power to do useful work is termed industrial connectivity. For instance, components including relays, motor starters, terminal blocks, and connectors are all typical connectivity components.

Generic connectors can use low-cost material as they merely maintain electrical continuity. However, based on operating environments, connectors are differentiated into four categories: hermetic, military, industrial, and commercial. While hermetic connectors offer maximum exclusion of their inner structural materials from the elements, military and industrial connectors handle more rugged environments with hazards including thermal shock, vibration, corrosion, physical jarring, dust, and sand. Most commercial applications do not make such extreme demands of connectors, and therefore, atmospheric and temperature conditions are the least critical factors that affect the performance of commercial connectors. This allows designers to select from different connector materials.

Brass

This is a metal alloy made from copper and zinc, with manufacturers varying the proportions to create varying properties. Although brass has excellent conductivity, it cannot withstand abrasion from many cycles of insertion and withdrawal. It undergoes crystallization under repeated stress and loses flexibility as it ages. Suitable for non-critical and low-contact-force applications, it is easy to braze, weld, solder, and crimp brass.

Beryllium Copper

With excellent electrical, mechanical, and thermal properties, beryllium copper easily resists corrosion and wear. Among all copper-based spring alloys, beryllium copper is stronger and more resistant to fatigue, while able to withstand repeated insertion and withdrawal cycles. However, it is the most expensive among all basic contact materials.

Nickel-Silver Alloys

Not always requiring plating, nickel-silver alloys resist oxidation. While contacts made of nickel-silver alloys are susceptible to stress corrosion, the extent does not exceed that of brass.

Gold

Gold, a highly stable plating material, is an excellent conductor inferior only to silver and marginally so to copper. With the lowest contact resistance and providing the best protection from corrosion, manufacturers use hard gold plating for contacts experiencing frequent insertion/withdrawal cycles. For even greater frequency of cycling, gold impregnated with graphite offers only a slight increase of contact resistance.

Silver

A general-purpose plating metal for power contacts, silver has a poor shelf life and tarnishes when exposed to the atmosphere. Although this increases the contact resistance, the oxide coating does not affect contacts carrying higher currents.

Nickel

With good corrosion resistance, nickel offers low contact resistance and fair conductivity. Therefore, it is used as an undercoat to prevent migration of silver through gold in high-temperature environments. Although it has good wear resistance, nickel may crack during crimping unless properly plated onto the base material.

Rhodium

Manufacturers use rhodium for contacts that need exceptional wear qualities. Although conductivity of rhodium is lower than that of gold or silver, the higher resistance is acceptable for thin coatings.

Tin

Providing good conductivity and excellent solderability, tin offers a low-cost finish and poor wipe resistance. This makes it the most suitable for connections requiring only very few mating cycles. Tin, not being a noble metal, will corrodes easily.

Gold-Over-Nickel

This is a widely used plating combination as it offers the surface qualities of gold, while minimizing the amount of gold required. The hard under-plating of nickel prevents migration of the base metal.

Importance of Resolution in Thermal Imaging

Thermal imaging technologies have long been associated with a range of applications and industries for discovering abnormalities and weak points quickly and efficiently. These technologies are ideal for production monitoring and other applications as materials and components undergo non-destructive testing under operating conditions. That allows discovery of the problem before a breakdown can occur or a fire risk can develop.

For instance, thermal imaging allows contractors in a building, facilities maintenance, HVAC, and in electrical industries to visualize situations they are facing—they know where to start with as job, and it saves them time and effort. That means they can improve their efficiency, ultimately providing faster service to customers.

Resolution of the image is very important in thermal imaging. The details matter when using thermography for detecting leakages, cold bridges, mold, or overheated components. Most such elements are visible only when the resolution of the image is 160×120 pixels or more. As the technology uses each pixel as a measurement point, measuring accuracy improves with higher resolution. Accurate measurements are necessary for detecting irregularities earlier, avoiding unnecessary damages for you and the customer.

Using a camera with exceptional resolution has additional advantages. It is not necessary to be near the abnormality when capturing its thermal image, thereby leaving the image quality unaffected. Low-resolution thermal images can be unclear, and may not offer true or accurate readings. Therefore, industrial thermal imaging practically starts from a resolution of 160×120 pixels, as this is the minimum to offer true value.

Several industries use thermal imaging. However, for the best application of this technology, it is necessary to use a robust, quality camera. Here are some examples where thermal imaging is a huge advantage:

Heating Installations

A thermal camera can make visible a leaking pipe hidden under plaster, which is impossible to locate with the naked eye. Similarly, it is easy to visualize under the floor heating courses, and check the performance of a radiator non-intrusively. In addition to the resolution, it is necessary to have a thermal sensitivity of at least 100 mK.

Inspection of Switching Cabinets

A temperature rise usually precedes a malfunction in a switching cabinet. Using a high-resolution thermal camera, not only can one measure this rise, but also visualize the location of the heat source. As all this happens without contact, it is impossible to miss an overheated contactor, an insufficiently tightened clamp, or an overloaded cable.

Discovering Defects in Buildings

Detecting sealing and insulation defects or discovering and analyzing cold bridges in buildings can be done far more quickly and accurately using thermal imaging than with any other tool. Apart from initiating preventive measure timely, this ensures building quality, while impressing the customer with the visual representation of the quality of workmanship.

Identifying Dangers from Mold

With high-quality thermal imaging, it is easy to calculate the value of humidity at each measuring point. The calculation depends on the externally measured ambient temperature, the humidity of air, and the determined surface temperature. The imager has a humidity palette, which represents the different risk zones with the principle of traffic lights—Green for no risk, Amber for caution, and Red for danger.

What are Miniature Circuit Breakers?

Most places that earlier used fuses in low voltage electrical networks now commonly use miniature circuit breakers (MCB) instead. Although an MCB is much larger than a fuse holder is, the MCB has several advantages when compared to fuses.

Any abnormal condition of the network, meaning overload or fault conditions, causes the MCB to sense and automatically switch off the electrical circuit. While a fuse does not sense it, the MCB senses the abnormality in a more reliable way. Additionally, the MCB is a more sensitive device for sensing an overload than the fuse.

A blown fuse can only be confirmed by opening the fuse grip or cutout from the fuse base. For an MCB that has tripped, the switch-operating knob comes down to its off position, and this is easily visible from a distance. That allows the faulty zone of the electrical circuit to be identified easily.

Restoring the operation of supply after repair of fault takes time as the blown fuses have to rewired or replaced with the proper type. With an MCB, restoration is very quick, as it involves only switching on operation.

Deciding on a fuse for protecting an electrical circuit is not easy, as it involves selecting the proper wire gauge and material. In most cases, people use any readily available thin wire as a fuse. Comparably, deciding on an MCB is much easier, as the manufacturer offers all the specifications that help in taking a decision.

An MCB is more expensive than the cost of a simple fuse wire and base. However, the benefits of the MCB more than compensate for the increase in expenses. Although very robust and maintenance free, the MCB has to be periodically switched off and on for the spring inside to retain its tension. A non-working MCB has to be simply replaced by a new one when it malfunctions.

The MCB protects an electrical circuit from two major faults—overcurrent and short circuits. The mechanism of the MCB tripping differs for the two faults. Long time overload current causes thermal heating, which affects a bimetallic strip. As the bimetallic strip bends, it ultimately disconnects the circuit.

Shorts in the circuit are more dangerous, as they cause a huge rush of current within a very short time. The circuit may catch fire before the bimetallic strip can heat up sufficiently to trip. To overcome this, MCB has an electromagnetic plunger associated with a tripping coil. A sudden increase in the current levels trips the electromagnetic plunger, opening the circuit breaker.

Some MCBs have three positions of operation. The means of manual opening and closing operation of the MCB are designated as ON and OFF. The third position is marked as TRIPPED. This makes it easy to determine the condition of the MCB whether it has been manually closed, tripped, or has been manually switched off.

For an MCB, the trip unit is its main part. It is responsible for the proper working of the MCB. As with the fuse, for an MCB also, the important factor is the time it takes to trip. The manufacturer of the MCB gives this as the I2t figures.

LCD Touchscreens for the Raspberry Pi

Those using the single board computer, the Raspberry Pi (RBPi), can now get several high-resolution LCD screen models on the market. While they are cheap, some are designed to integrate with the RBPi specifically. SunFounder, a company specializing in accessories and kits for RBPi and Arduinos, produce a series of these screens. For satisfying different segments in the market, SunFounder has lately produced and is marketing a number of models with varying price ranges.

SunFounder LCD 10.1” HD

With a resolution of 1280×800, this high definition LCD is a true gem for RBPi fans. The screen has appropriate screw supports for use as a desktop screen. If you remove the supports, the screen can be used in any other context as well. The rear of the screen has a compartment with an electronic screen presenting input connectors in other formats such as VGA and AV, including HDMI. The back also has provision for mounting the RBPi and fixing it with screws. As the networking sockets and USB ports of the RBPi remain at the edge of the screen, cable connections are not hindered.

This high quality display has low weight and is highly adaptable to other purposes. That means you can screw it on different types of support, for which it has adequate arrangements. The viewing angle is also very good, and one is not forced to look at the upper front of the screen to be able to work with this model.

SunFounder LCD 7” HD

Significantly cheaper than its 10” elder brother, this 1024×600 TFT LCD is very compact and has convenient dimensions. However, it has a smaller viewing angle, considering this is purely a desktop model. Apart from HDMI, the LCD accepts inputs such as VGA, AV1, and AV2.

Kuman LCD 7” HD

Technically identical to the SunFounder 7”, this LCD is equipped with a touch screen. As this is somewhat cheaper, the 1024×600 Kuman TFT LCD is more economical. However, it is slightly heavier than its rival is. It accepts HDMI, VGA, and AV inputs.

SainSmart LCD 7”

If you are looking for something still cheaper, and able to sacrifice some resolution, the SainSmart model should appeal to you. At a resolution of 800×480, this TFT LCD also includes a touch screen. However, this is not a desktop model, and you must arrange for a suitable housing. Weighing considerably lower than the others do, it accepts inputs in the form of HDMI, VGA, AV1, and AV2.

Raspberry Pi LCD 7”

Although officially released by the Raspberry Foundation, this 800×400 LCD model is comparatively expensive. However, it comes with a touch screen and has a video shield for the RBPi boards. The case housing must be purchased separately, which adds to the cost.

Kuman 7”

If you are looking for a model you can assemble, this 800×480 model from Kuman makes that possible. This is the same as the other Kuman model, but less expensive. Additionally, it has a touch screen and a remote control. It accepts input formats such as HDMI, VGA, and AV.