Category Archives: Guides

Mimicking Nerves with Memristors

Researchers are planning to build a computer mimicking the monumental computational power of the human brain. For this, they prefer to use memristors, because these devices vary their electrical resistance on the basis of the memory of their past activity. Memristors are semiconductor devices, and at NIST, the National Institute of Standards and Technology, researchers demonstrate the long and mysterious manner of the inner workings of memristors, explaining their ability to behave as the short-term memory of human nerve cells.

Nerve cells signal one another, but how well they do so depends on the frequency of their recent past communication. In the same way, the resistance of a memristor also depends on the current flow that went through it very recently. The best part is memristors remember even with their electrical power switched off.

Researchers read the memristor with the help of an electron beam. As the beam impinges on various parts of the memristor, it induces currents depending on the resistance value of that part. Traversing the entire device, this yields a complete image of variations of current throughout the device. By noticing the nature of the current variations, it is possible to indicate the places that may fail, as these show overlapping circles within the titanium dioxide filament.

So far, during their study of memristors, scientists have not been able to understand their working, and neither could they develop standard tool-sets for studying them. Now, for the first time, scientists at NIST have been able to create a tool-set that can probe the working of memristors deeply. They envisage their findings will pave the way for operating memristors more efficiently, and minimize current leaks from them.

For exploring the electrical functioning of memristors, the scientists focused a beam of electronics at various locations on the device. The beam was able to knock some of the electronics from the titanium dioxide surface of the device. The free electrons formed an ultra-sharp image of each of the locations. The beam also caused four clear-cut levels of currents to flow through the device. According to the researchers, several interfaces of materials within the memristor were the cause. Typically, a memristor has an insulating layer separating two conducting metal layers. As the researchers could control the position of the electron beam inducing the currents, they were able to know the location of each of the currents.

By imaging the device, researchers located several dark spots on the memristor. They surmised these spots to be regions of enhanced conductivity. These were the places from where there was a greater probability of currents leaking out of the memristor during its normal operations. However, they found the leaking pathways to be beyond the core of the memristor, and at points where it could switch between high and low resistance levels.

Their finding opened up a possibility of reducing the size of the device to eliminate some of the unwanted current leaking pathways. Until now, the researchers were only able to speculate on the current leakages, but had no means of quantifying the size reduction necessary.

What is 3D MLC NAND Flash Memory?

To unleash performance fit for the next generation of computers, Transcend has released its MTE850 M.2 Solid State Device (SSD), based on 3D MLC NAND flash memory. The device utilizes the PCI Express Gen3 x4 interface and supports the latest NVMe standard. According to Transcend, this SSD targets high-end applications such as gaming, digital audio and video production, and multiple uses in the enterprise. Typically, such applications demand constant processing of heavy workloads, while not willing to stand any system slowdowns or lags of any kind. Transcend claims the MTE850 M.2 SSD will offer users high-speed transfers and unmatched reliability.

High Speeds for High-End Applications

As the above SSD uses the PCIe Gen3 x4 interface and follows NVMe 1.2 standard, it transmits and receives data on four lanes simultaneously. This results in the SSD working at the blazing speeds of up to 1100 MBps while writing, and up to 2500 MBps while reading.

Why the PCIe Interface

Presently, the most popular method of connecting a host computer to an SSD is through SATA or Serial ATA interface. However, PCIe uses one transmit and one receive serial interfaces in each of the four lanes, the PCIe interface is much faster than SATA is, and it is able to fulfill new performance requirements in better ways.

Why the NVMe Standard

The growing needs of enterprise and client applications demands better performance vectors than the Advanced Host Controller Interface (AHCI) can provide. The NVM Express (NVMe) fulfills this enhanced host controller interface standard, which also calls for low latency, increased IOPS, and scalable bandwidth.

What is 3-D Expansion?

Existing planar NAND memory chips are arranged in the form of flat two-dimensional arrays. In contrast, 3-D NAND flash has memory cells stacked in the vertical direction as well as in multiple layers. This breaks through the density limitations of the existing 2-D planar NAND, with the 3-D NAND offering a far greater level of performance and endurance.

With Better Endurance Comes Higher Reliability

To help keep data secure, Transcend has engineered their MTE850 M.2 SSD with a RAID engine (a type of data storage virtualization technology) and Low-Density Parity Check (LDPC) coding, along with an Elliptical Curve Cryptography (ECC) algorithm. Additionally, Transcend manufactures their SSDs with top-tier MLC NAND flash chips and provides them with engineered dynamic thermal throttling mechanism. This way, Transcend ensures the MTE850 delivers superior stability and endurance befitting for high-end applications.

SSD Scope Software

Users can download the SSD Scope software application free of charge from the Transcend site. The application helps to monitor the health of the running SSD using SMART technology and allows the user to enable the TRIM command to obtain optimum write speeds. Using the application also keeps the firmware of the SSD up-to-date, and helps in migrating data from the original drive to the new SSD with only a few clicks.

With certificates from CE, FCC, and BSMI the #-D MLC NAND flash memory based MTE850 M.2 SSD from Transcend works on 3.3 VDC ±5%, operating within 0 and 70°C. With mechanical dimensions of 80x22x3.58 mm, the SSD weighs only 8 grams.

What are Synchronous Condensers?

All manufacturing and industrial plants around the world face the unique problem of lagging power factor. Ideally, the voltage and current vectors should align perfectly for any AC power system feeding a load. In actual practice, however, the current either leads or lags the voltage by a few degrees, depending on whether the load is capacitive or inductive. Power factor is the cosine of the angle the current vector makes with the voltage vector as the reference. A positive power factor less than unity leads to reactive energy drawn from the supply, and rather than being converted to useful work, the reactive energy is wasted as heat generated in the system.

One of the methods of bringing the power factor back to unity or near to unity is the synchronous condenser, which when connected to the system, dynamically delivers the reactive power required as an uninterrupted reference source for improvement. The condenser adjusts the excitation level automatically and thereby maintains the power factor to the desired level. The synchronous condenser improves the overall power quality of a power system as it helps to reduce voltage transients, creates a more uniform sine waveform, and reduces the harmonic distortions in the system. All these advantages make the synchronous condenser a critical factor for any power facility.

In practice, the level of excitation of the synchronous condenser depends on the amount of power factor correction necessary and the level sensed by the controls of the condenser. The condenser then adjusts its excitations levels automatically for maintaining the power factor at the specified setting. The synchronous condenser adjusts the power factor without creating switching transients, and it remains unaffected by harmonic currents that the solid-state motor drives produce.

In contrast to conventional methods of power factor correction, using a synchronous condenser results in a much smoother waveform and does not affect a system adversely, when loaded with current harmonics. As the condenser is a low impedance source, it appears as inductive to loads.

Synchronous condensers are usually fitted with frequency, voltage, and temperature sensors that protect the system against overload and other dangerous situations. The solid-state voltage and power factor regulators within the synchronous condenser to a precision job, and switchboard grade meters keep track of the VAR and power factor. All this instrumentation makes sure the power supply system operates at its peak performance 24/7. To make it compatible to any industrial applications, manufacturers of synchronous condenser usually provide them with color touch screen displays and means of communicating remotely.

Synchronous condensers offer several advantages. These include elimination of power bill penalties, automatic power factor corrections, increased system stability, mitigation of voltage transients, reduction of system losses, and lowering the overall maintenance costs.

As synchronous condensers do not have to supply a torque, there is usually no output shaft. Enclosed in a leak-proof shell, the synchronous condenser is filled with hydrogen to help with reducing losses from wind friction and cooling. As hydrogen is lighter than air by about 7%, the wind friction or windage losses are reduced by 7% for a unit filled with hydrogen over that containing air. Additionally, heat removal improves by a factor of ten.

Using Relays to Detect Faults

Different types of relays are in use in every-day life. These include relays constructed from electromechanical elements such as from solenoids, induction discs, hinged armatures, or from solid-state elements such as from transistors, magnetic or operational amplifiers, silicon-controlled-rectifiers (SCRs), diodes, or digital computers using microprocessors and analog-to-digital converters.

Development of protection with relays began with the electromagnetic types, and most descriptions of relay characteristics still retain the electromagnetic terms. Although the construction of a relay does not inherently alter the concept of protection, each type has its own advantages and disadvantages.

General faults are often short circuits, where the current increases in magnitude, while the voltage goes down. Apart from the changes in magnitude, the AC field may also undergo changes in parameters such as system frequency, active/reactive power, harmonic components, phase angles of the current and voltage phasor, and more.

Operating principles of detection of faults with relays are based on detecting the above changes and identifying whether the changes exist within the predefined zone of protection or outside. Depending upon the operating principle of the relay, detection can be categorized based on which of the input quantities the specific relay will respond. This leads to eight major types of faults that relays can detect:

Frequency Sensing
Harmonic Content
Pilot Relaying
Distance Measurement
Phase Angle Comparison
Differential Comparison
Magnitude Comparison
Level Detection

Most power systems operate at a normal frequency of 50 or 60 Hz, depending on the country. Deviating from the normal frequency indicates an existing problem or an imminent one. Engineers use frequency-sensing relays to detect and take corrective action to bring the system frequency back to normal.

Power systems usually operate with a sinusoidal waveform of the fundamental frequency. Abnormal system conditions create harmonics that are typically associated with heat and loss in efficiency. Electromechanical or solid-state relays can detect these harmonics, based on which control action may be required.

Sometimes information is required from a remote location, and a pilot relay provides it in the form of contact status, open or closed. Usually, this information is carried over a channel of communication using telephone, microwave, or carrier circuits.

An impedance relay determines the distance or length of the line based on a given spacing and diameter of the conductor. The relay compares the local voltage with the local current, and gives a measurement of the line impedance as seen from its terminals.

A phase angle comparison relay compares the relative angle of phase between the AC voltage and the AC current, measuring the power factor angle. This comparison determines the direction of flow of the current with respect to the voltage, with the magnitude of the angle measured giving an indication of faults.

Under normal operating conditions, current entering one end of an electrical equipment should equal the current exiting from the other end. However, in case of any fault within the equipment, this balance is no longer maintained. A differential relay detects the difference in the two currents, and provides protection.

Relays can compare the magnitude of current in one circuit with the magnitude of current in another and detect abnormalities based on whether they should have been equal or proportional.

Finally, relays can be designed to trip the circuit breakers should the operating current level crosses a specific setting.

Which are Better – Round Cables or Flat Cables?

Both types of cables are available in the market—round ones and flats, and people use them according to the requirements of the application. As round cables were the first to arrive on the market, the industry has been using them as standard for long, in applications ranging from renewable energy to automation and manufacturing in general.

Flat cables arrived late on the scene, and offer a niche solution presently. However, they are gaining ground steadily for applications within the civil-aircraft markets, semiconductor industry, medical field, and for supplying data and power to machines. Flat cables are also called festoon cables, and the overhead crane companies actively use them for applications where winding cables around spools is difficult.

Comparison of Electrical Performance

The protection for internal EMI depends heavily on the construction of the cable. In general, flat cables do not transfer data very well. Individual shielded pairs within flat cables are necessary to provide coupling and crosstalk protection from pair to pair.

Most shielding materials to not hold a flat format and tends to become round. This makes it difficult to place a shield on the flat cable overall. This also makes it difficult to protect and shield a flat cable from the effects of external EMI. The naturally round shielding tendency provides greater protection against influences of external EMI on round cables.

The length of a cable, its quality of insulation, and the resistance of its conductors determines the voltage drop or attenuation on a power cable and this is immaterial whether the cable is round or flat. In both cases, higher quality of insulation and proper positioning of the ground wire improves the attenuation. Certain industries demand very high-performance (low attenuation and crosstalk) flat cables. With proper shielding, it is possible to transmit both power and signals through the same cable.

Comparison of Mechanical Performance

Cables in the industry face mechanical stresses of four main types—S-bend, rolling flex, tic-toc, and torsion. The natural capability of being able to move in multiple axes at the same time makes round cables capable of withstanding all the stresses. For instance, round cables can flex 30 million times in certain applications. On the other hand, flat cables can withstand only rolling flex, as the movement is only in one linear axis.

Movements in several axes such as during torsion can lead to flat cables binding, or twisting beyond a certain point. When under torsional loads, flat cables can spool and twist over a certain length. Preventing this requires every component of a flat cable to be integrated at the right position and twist. It also requires the cable to be embedded or wrapped with a PTFE (Teflon) tape for minimizing the frictional forces during torsion.

Summary

Round cables can maximally utilize the space inside the smallest required cross-sectional area. Drilling a round hole is easier than cutting a rectangle. Therefore, most machine or panel openings use round cables where using a flat cable may be more difficult, as it has an elongated cross-section. However, it is possible to stack flat cables to make them fit together in a smaller space than it is with round cables.

Raspberry Pi to Linux Desktop

You may have bought a new Single Board Computer (SBC), and by any chance, it is the ubiquitous Raspberry Pi (RBPi). You have probably had scores of projects lined up to try on the new RBPi, and you have enjoyed countless hours of fun and excitement on your SBC. After having exhausted all the listed projects, you are searching for newer projects to try on. Instead of allowing the RBPi to remain idle in a corner, why not turn it into a Linux desktop? At least, until another overwhelming project turns up.

An innovative set of accessories converts the RBPi into a fully featured Linux-based desktop computer. Everything is housed within an elegant enclosure. The new Pi Desktop, as the kit is called, comes from the largest manufacturer of the RBPi, Premier Farnell. The kit contains an add-on board with an mSATA interface along with an intelligent power controller with a real-time clock and battery. A USB adapter and a heat sink are also included within a box, along with spacers and screws.

Combining the RBPi with the Pi Desktop offers the user almost all functionalities one expects from a standard personal computer. You only have to purchase the solid-state drive and the RBPi Camera separately to complete the desktop computer, which has Bluetooth, Wi-Fi, and a power switch.

According to Premier Farnell, the system is highly robust when you use an SSD. Additionally, with the RBPi booting directly from an SSD, it ensures a faster startup.

Although several projects are available that transform the RBPi into a desktop, you should not be expecting the same level of performance from the RBPi as you would get from a high-end laptop. However, if you are willing to make a few compromises, it is possible to get quite some work done on a desktop powered with the RBPi.

Actually, the kit turns the RBPi into a stylish desktop computer with an elegant and simple solution within minutes. Unlike most other kits, the Pi Desktop eliminates a complex bundle of wires, and does not compromise on the choice of peripherals. You connect the display directly to the HDMI interface.

The added SSD enhances the capabilities of the RBPi. Apart from extending the memory capacity up to 1 TB, the RBPi can directly boot up from the SSD instead of the SD card. This leads to a pleasant surprise for the user, as the startup is much faster. Another feature is the built-in power switch, which allows the user to disconnect power from the RBPi, without having to disconnect it from the safe and intelligent power controller. You can simply turn the power off or on as you would on a laptop or desktop.

The stylish enclosure holds the add-on board containing the mSATA interface and has ample space to include the SDD. As the RBPi lacks an RTC, the included RTC in the kit takes care of the date and time on the display. The battery backup on the RTC keeps it running even when power to the kit has been turned off. There is also a heat sink to remove heat built-up within the enclosure.

Battery Monitoring with Comparators

So many portable consumer electronics gadgets in use today use small, button- or coin-cell batteries. Sometimes it is necessary to monitor their state-of-charge (SOC) and health efficiently without affecting their SOC significantly, but this can be a challenge. However, simple low-power monitoring circuits for small batteries using comparators can overcome this challenge.

Managing Batteries in Portable Systems

Usually, the system engineer budgets the system power requirements carefully during the system design. A micro-controller or microprocessor within the gadget is the actual brains that manages the system reliably and performs the required functions. Since it is typical for the controller to be power-hungry, as it is the workhorse of the system, there is not much sense in making the controller do all the work. To prevent unnecessary power dissipation, the controller is designed to remain asleep for extended periods, only waking up when flags are presented on the GPI pins.

Therefore, engineers resort to using low-power circuits for continually monitoring the vital functions of the system. When these circuits detect an event, they flag the micro, usually in the form of interrupts. The micro then wakes up to perform its required duty. One of the vital functions of such circuits is to monitor the state of the battery. When the battery voltage dips below the pre-defined threshold, it means it has discharged and requires charging. Likewise, as soon as the battery voltage crosses another pre-defined threshold, it means it is completely charged with no further requirement of further charging. Similarly, it is important to monitor the case temperature of the battery and the ambient temperature, as this provides much information about the loading conditions on the battery, and the presence of a fault.

Using Comparators for Monitoring

Although there are sophisticated battery monitors with fuel gauges, and monitoring battery voltage and temperature with an analog-to-digital converter is possible, these essentially require careful tradeoffs with portable gadgets. A designer must consider form factor, cost, accuracy, speed, and power consumption when creating the design, as different systems may have different priorities.

It is possible to have a simple comparator monitoring the voltage at the battery terminals. For a fully charged battery, the output voltage of the comparator transitions from high to low and from low to high for indicating a fully discharged battery. When implemented with external hysteresis, thresholds can be pre-defined to yield the proper output states.

The comparators can be tiny-footprint devices with internal references, consuming very low quiescent currents. When large-value resistors are used in the circuit, the overall operating current will be comparable to the typical self-discharge rate of the battery. By designing the circuit to operate from a low supply voltage of about 1.7 V and consuming less than 2 µA of current, the circuit will be able to produce the proper output state even when the battery has only a minimum charge remaining.

The component values necessary to realize the application for battery state monitoring must be selected with care. The determined threshold value should provide a narrow band of hysteresis to allow for more cushion for component variation and tolerances. Using resistors with 0.5% makes the circuit work with ±1% accuracy.

What are Miniature Slide Guides?

Slide guides are industrial mechanical guides to reduce friction in linear motions. They use rolling elements, either hardened steel rollers or balls, moving along two raceways, with a stick-slip arrangement. This provides a smooth linear motion in either direction even when the load is heavy. Usually, slide guides carry their loads on one or more blocks or carriages riding on a rail. Instead of carrying loads, they can also guide other components, making sure they move smoothly and easily along the rail. The rail length depending on the required length of the application is usually made up of several straight sections. For some slide guides, the linear motion can be unlimited in distance, as the rolling elements travel in recirculating paths.

Since the guides are not powered, they cannot provide the drive to move the load. The force to move the load actually comes from a mechanism such as a linear actuator, lead screw, ball screw, or a belt-and-pulley arrangement. A limit switch or some other form of brake outfitted on the linear drive is necessary to stop the motion on a slide guide. Users may also use other stopping mechanisms such as end stoppers or a bumper pad may also be used to halt the motion.

Applications where the space and weight are both limited use miniature slide guides. Although these offer the same functionality and have the same form, miniature slide guides are limited to being only 25 mm in height, and 13 mm or less in width.

People call miniature slide guides with different names such as mini carriage on a profiled guide rail, or mini linear guides. Available in a range of sizes, the performance capabilities of mini slide guides scale with use.

For instance, a load carrying block may be as small as 6 X 12.9 mm, weigh as much as 0.8 gm., and ride on 100 mm rails carrying a load of 2.8 gm. The dynamic load rating for such small guides would be 0.21 kN.

On the other extreme, a block weighing 338 gm., with dimensions of 46 x 79.5 mm, may ride on 100 mm rails with a load of 209 gm. The dynamic load rating for such a large guide would be 12.4 kN. The top speed with which a mini slide guide typically moves is about 1.5 m per second.

Despite their compact size, mini slide guides direct their motion along a linear axis, much as their larger counterparts do. Their main advantage comes from the compact size, allowing them to be used in devices such as robots, medical devices, wafer-fabrication equipment, and hard-disc drives. The mini slide guides also use either balls or rollers as their friction reducing elements.

Mini slide guides use rolling ball elements made of stainless steel or carbon steel. They can support heavy loads and offer a long operational life. An all-stainless-steel construction is best suited for applications such as vacuum or clean rooms.

Mini slide guides that use roller or cylindrical elements offer lines of contact area rather than point contacts as balls do. This allows them to carry heavier loads than slide guides using rolling ball elements can.

Measuring Very High Currents

High currents, such as 500 Amps and above, are common nowadays. Industries regularly use equipment consuming high currents, and vehicle batteries experience very high currents for a short time during starting. With vehicles increasingly trending towards their electric versions, it is becoming necessary to be able to measure high currents with precision. Increasingly, it is increasingly becoming critical to monitor current consumed accurately for ensuring performance and long-term reliability.

Current sensing is necessary for essential operations such as battery monitoring, DC to DC converters, motor control, and so on. Device specification mainly defines the performance of any current sensor solution. This includes the efficiency, precision, linearity, bandwidth, or accuracy. However, for designers designing a system to satisfy all the requirements of the specifications can be a challenging task. One way to do this is to use a precision shunt, a shunt monitor, and a signal conditioner.

The ±500 A precision shunt-based current sensor design from Texas Instruments (TI) has an accuracy of 0.2% of full scale reading (FSR) over a huge temperature range of -40 to +125°C. Several applications such as motors and battery management systems require such precision current sensing. In general, these applications suffer from poor accuracy caused by shunt tolerances, temperature drift, and non-linearity. Shunt monitors such as INA240, and signal conditioners such as PGA400-Q1 from TI help to solve these problems.

The design from TI works on 48 V or 12 V battery management systems and is suitable for measuring ±500 A, with both high- and low-side current sensing. It accurately compensates for temperature and non-linearity to the second order with an algorithm. Furthermore, it offers protection against harness faults such as input/out signal protection, reverse polarity, and overvoltage. TI has protected its design from electromagnetic interference.

Several ways of measuring currents are available, and these include using magnetic saturation, magneto-resistance methods, Lorentz force law, Ohm’s law, Faraday’s induction law, and more. While each technology presents its own advantages and disadvantages, every customer has his or her own preference and place of use for the specific topology they prefer to choose.

The simplest and most common technology makes use of Ohm’s law, which this TI design also uses. When designing the system for measuring currents, essentially the designer must choose where the current is to be measured—high side or low side, the range of measurement, and whether the current is uni-polar or bi-directional. These parameters define the suitable topology and the design the designer must use. Most vehicle systems now prefer to use 48 V and this new trend implies the current sensor will have to measure a large span of range.

The method of measurement follows a simple process. The ±500 A current passes through the shunt whose resistance measure 100 µΩ. This causes a noticeable amount of voltage drop across the shunt. The current sense monitor INA240 measures this small amount of voltage and passes it on to the signal conditioner, PGA400-Q1. The delta-sigma ADC micro-controller inside PGA400-Q1 creates a ratio-metric voltage between 0.5 and 4.5 V using its linearity and compensation algorithms.

Let the Raspberry Pi Monitor Energy

If you are looking for monitoring energy remotely, an open source system that uses the ever-popular single board computer, the Raspberry Pi (RBPi) may be suitable. The company, OpenEnergyMonitor, makes the open-source tools for monitoring energy, and at present, they are using the RBPi3. According to their co-founder Glyn Hudson, the aim of OpenEnergyMonitor is to help people understand and relate to how they use energy from their energy systems, and the challenges of sustainable energy.

The system uses five main units. Users can assemble and configure these to work in a variety of applications. Both hardware and software in the system is fully open-source, and the hardware is based on Arduino and RBPi platforms. Users can opt to use the system for monitoring home energy, monitoring solar PV, and or monitoring temperature and humidity.

emonPi

When configuring the OpenEnergyMonitor system, emonPi, as a simple home energy monitoring system, it allows measuring the daily energy consumption and analyzing real-time power use. The all-in-one energy-monitoring unit, emonPi is a simple installation based on the RBPi, requiring only an Ethernet or Wi-Fi connection at the meter location.

Clip-on CT sensors on the emonPi enable it to monitor independently two single-phase AC circuits simultaneously. While the emonPi can monitor temperature, it has an optical pulse sensor to interface directly with the utility meters, which means the emonPi has to be installed next to the utility meter.

The emonPi comes with Emoncms, the open-source web application. This helps in logging and visualizing energy use along with other environmental data such as temperature and humidity. It has two power outlets and requires Ethernet or Wi-Fi to transfer data. The RBPi operates on a pre-built OS on an SD card included with the energy monitor. The 5 VDC power required has to be fed in from an external power supply unit.

As power is the product of voltage and current, the emonPi requires an AC-AC voltage sensor adaptor and a clip-on CT sensor. While the emonPi comes with one CT sensor as standard, it can accept two CT sensors.

emonTx

For remote monitoring, users can use emonTx, a remote sensor node as an alternative to emonPi. The emonTx runs as a standalone unit, with an ESP8266 Wi-Fi module running EmonESP. This can post directly to Emoncms without using emonPi or emonBase.

Users can monitor a maximum of four single-phase AC circuits with the clip-on CT sensors using the emonTx. A plug-in AC-AC adaptor powers the unit, and provides the AC voltage sample, which the emonTx uses for real-time power calculations. If AC power is not available, emonTx can be powered using four AA type batteries.

Optional LED Pulse Sensor for Utility Meter

This sensor allows interfacing directly with utility meters that have LED pulse output. It is compatible with emonTx and emonPi, and reports the exact amount of energy as the utility meter does. Although best used together with clip-on CT sensors, the LED pulse sensor cannot measure instantaneous power.

emonBase

This is a web-connected gateway, consisting of an RBPi and RFM69Pi RF receiver board. It receives data via a low power RF carrier at 433 MHz from emonTx or emonTH and offers local and remote data logging using Emoncms.