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1.2V-25V/10A Adjustable Power Supply Using Power Op-Amp

Posted on by mixos

This is a small size power supply based on OPA549 power op-amp that provides output voltage 1.2V to 25V with 0 to 10A adjustable current limit. Two onboard trimmer potentiometers provided to adjust the voltage and current, LED D1 is over temperature indicator. The circuit works with input supply of 30V DC and logic supply 5V DC. IC requires large size heat sink to work with full 10A current range. Screw terminals for input and output connections are provided. The OPA549 is a low-cost, high-voltage/high-current operational amplifier ideal for driving a wide variety of loads. This laser-trimmed monolithic integrated circuit provides excellent low-level signal accuracy and high output voltage and current. The OPA549 operates from either single or dual supplies for design flexibility. The input common-mode range extends below the negative supply.

1.2V-25V/10A Adjustable Power Supply Using Power Op-Amp – [Link]

1.2V-25V/10A Adjustable Power Supply Using Power Op-Amp

This is a small size power supply based on OPA549 power op-amp that provides output voltage 1.2V to 25V with 0 to 10A adjustable current limit. Two onboard trimmer potentiometers provided to adjust the voltage and current, LED D1 is over temperature indicator. The circuit works with input supply of 30V DC and logic supply 5V DC. IC requires large size heat sink to work with full 10A current range. Screw terminals for input and output connections are provided. The OPA549 is a low-cost, high-voltage/high-current operational amplifier ideal for driving a wide variety of loads. This laser-trimmed monolithic integrated circuit provides excellent low-level signal accuracy and high output voltage and current. The OPA549 operates from either single or dual supplies for design flexibility. The input common-mode range extends below the negative supply. The OPA549 is internally protected against over-temperature conditions and current overloads. In addition, the OPA549 provides an accurate, user-selected current limit. Unlike other designs which use a “power” resistor in series with the output current path, the OPA549 senses the load indirectly. This allows the current limit to be adjusted from 0A to 10A with a resistor/potentiometer, or controlled digitally with a voltage-out or current-out Digital-to-Analog Converter (DAC). The Enable/Status (E/S) pin provides two functions. It can be monitored to determine if the device is in thermal shutdown, and it can be forced low to disable the output stage and effectively disconnect the load. The OPA549 is available in an 11-lead power package. Its copper tab allows easy mounting to a heat sink for excellent thermal performance. Operation is specified over the extended industrial temperature range, –40°C to +85°C.

Features

  • Input Supply 30V DC
  • Logic Supply 5V DC
  • Output 1.2V to 25V DC
  • Load Current Limit Adjustable 0 To 10A
  • Thermal Shutdown LED Indicator

A programmable source and sink power supply can easily be built using the OPA549. Both the output voltage and output current are user controlled. See Figure 12 for a circuit using potentiometers to adjust the output voltage and current while Figure 13 uses DACs (refer to datasheet). An LED connected to the E/S pin through a logic gate indicates if the OPA549 is in thermal shutdown.

Adjustable Current limit

The OPA549’s accurate, user-defined current limit can be set from 0A to 10A by controlling the input to the ILIM pin. Unlike other designs, which use a power resistor in series with the output current path, the OPA549 senses the load indirectly. This allows the current limit to be set with a 0μA to 633μA control signal. In contrast, other designs require a limiting resistor to handle the full output current (up to 10A in this case). Although the design of the OPA549 allows output currents up to 10A, it is not recommended that the device be operated continuously at that level. The highest rated continuous current capability is 8A. Continuously running the OPA549 at output currents greater than 8A will degrade long-term reliability.

Schematic

Parts List

Connections

Photos

Video


OPA549 Datasheet

Could Sodium-ion Batteries be a Replacement for Li-ion Batteries?

Posted on by Maria Alejandra Escalante

Batteries made by Tiamat, a sodium battery startup spun off from the National Center for Scientific Research in France.

In early 1990s lithium-ion batteries started gaining popularity as a substitute for nickel-cadmium batteries. They have higher energy density, low self- discharge, and low maintenance, but it was soon found that they have short life span, unstability which causes security concerns and creates the need for protection circuits (to maintain it within safe limits), and are really expensive to produce. Lithium is scarce (or is soon going to be), only 0,06% of earth crust is made of this material and its mainly found in South America. A start up called Tiamat formed by scientists at several French universities proposed an alternative to lithium-ion batteries, they developed the first sodium-ion battery in industry standard 18650 cell size.

Unlike Lithium, sodium makes up 2.6% of earths crust which makes it the sixth most abundant element. As a raw material sodium sells at about $150 a ton compared to $15,000 a ton for lithium. Sodium batteries are cheaper to produce than lithium batteries, leading to a lower selling price. Also, the lifespan is about ten years compared to lithium which is 4 years and Sodium-ion batteries can last for up to 5000 charge/discharge cycles. Tiamat batteries are not a fire hazard, and provide more stability for a cheaper price.

Scientists want to use these batteries mainly for mass storage of interment renewable energies such as solar o wind. Tiamat is not looking to make Li-ion batteries disappear, instead they want to focus on their long lasting power, and use it for stationary storage. This type of battery could be used in electric cars to allow lasting trips with short recharge time. Production has not started, but when it is approved, and they start to sell France could become a leader in this type of technology. This startup has the support of RS2E (Réseau sur le stockage électrochimique de l’ énergie) a French research network dedicated to energy storage devices, and they plan to launch the product on 2020.

Nowadays, lithium batteries are used mainly for smartphones, laptops, and cars that means that if a new technology was going to replace them, a much better alternative would be needed. Even when sodium batteries are cheaper and safer they still have performance issues that could affect their sales, but as Tiamat said they are not looking to replace these and their market is completely different. For now, the cells produced offer only about half of the energy density of Li-ion and are yet to be improved in many aspects.

[Source]

Using an MMA7455 accelerometer with an ESP32 board

Posted on by mixos

by shedboy71 @ microproducts.net discuss how to use MMA7455 accelerometer with ESP32 board. He writes:

The MMA7455L is a Digital Output (I2C/SPI), low power, low profile capacitive micromachined accelerometer featuring signal conditioning, a low pass filter, temperature compensation, self-test, configurable to detect 0g through interrupt pins (INT1 or INT2), and pulse detect for quick motion detection. 0g offset and sensitivity are factory set and require no external devices. The 0g offset can be customer calibrated using assigned 0g registers and g-Select which allows for command selection for 3 acceleration ranges (2g/4g/8g). The MMA7455L includes a Standby Mode that makes it ideal for handheld battery powered electronics.

Using an MMA7455 accelerometer with an ESP32 board – [Link]

XMotion All In One Controller for Robotics

Posted on by mixos

If there is a motion, it must have XMotion. Recreating Arduino & interface circuits user focused.

XMotion is Arduino Compatible all in one robot controller. Which designed specially for robotics, IOT and maker projects.

It includes powerful Motor drivers, switching mode regulator, interface circuits and more. With protected features, it is all in one board for lots of different type robot projects.

But not only this. Also we added some supporting materials, like starter codes, libraries. If you want to do line follower, mini-sumo or any basic robot we have ready-made codes for beginners.

XMotion All In One Controller for Robotics – [Link]

NFC Key Protects Your Data by Disconnecting Chips From Antenna

Posted on by mixos

Cameron Coward @ blog.hackster.io writes:

Like most connected technology these days, near-field communication (NFC) is susceptible to hacking. By its very nature, NFC is normally accessible by anyone nearby. NFC, as it was originally intended, is designed to provide data wirelessly to any nearby readers without requiring a power source of its own.

Fortunately, N-O-D-E, one of our favorite open source hardware developers, has come up with a solution called the NFC Key. This handy little keychain-friendly device protects your NFC chips in the simplest way possible: by physically disconnecting them from the antenna. Without the antenna connected, the chips just cannot be powered or transmit data.

NFC Key Protects Your Data by Disconnecting Chips From Antenna – [Link]

Transistors- The 70-year-old invention that changed the world

Posted on by Maria Alejandra Escalante
First transistor made in 1947- Point contact transistor

Its been 70 years since the fundamental building block of electronics was created, and it has been getting smaller, and better since then. The invention that won the Nobel prize for John Bardeen, Walter Brattain, and William Shockley in 1956 revolutionized electronics and made it into the IEEE milestone list. Before 1947 computers used vacuum tubes, which could be several inches long, consumed massive amounts of power, and needed to be regularly replaced. Nowadays, billions of transistors can fit in the area of a single vacuum tube, can last for many years and are a lot more efficient.

What is a transistor? For computing, basic binary logic operations are needed in order to perform calculations, so the objective of both vacuum tubes and transistors was to toggle the device between on and off position (1 or 0). A transistor is made from semiconductor material (usually silicon or germanium) capable of carrying current and regulating its flow. The semiconductor is doped which results in a material that either has extra electrons (n type) or has holes in the crystal structure (p type), and the transistor is made from a combination (layers) of both of these types. When current is applied, electrons can go through the different layers allowing energy to flow. Transistors can work as a switch or an amplifier depending on how it’s configured.

In 1965, the intel co-founder formulated Moore´s Law which states that every 2 years the number of transistors in a dense integrated circuit doubles. Since then Gordon E. Moore has been right, but soon the law will no longer be true which will lead to either a slowdown in technologic advancement or a new golden era for engineering where a new technology will replace transistors and a race to make it better and more efficient will again begin.

Transistors have powered 70 years of advances in computing, and it all started with the point contact transistor made by three scientists who changed history. However, other ways must be found to make computer more capable, but the problem is not just making smaller transistors, but also about the time it takes for information to get from one side to another. Transistors can be found in cellphones, computers, cameras, electronic games, and pretty much anything electronic that performs calculations, so if transistors stop advancing so will all these devices. Perhaps, consumers won’t feel the impact right away, but scientists in need of fast processing and super computers will.

[source]

WattUp – RF based Wireless Charging at a Distance

Posted on by Maria Alejandra Escalante

Recently, many big companies such as Samsung have developed wireless chargers which work by induction. These chargers usually consist of a station which needs to be in contact with the device in order to charge. The station defeats the purpose of being able to move and walk while still charging the device. Energeous, a global leader in RF- based wireless charging, created the award-winning device WattUp in order to give mobile power to everyone.

The WattUp transmitter converts electricity into radio frequencies, then beams the energy to nearby devices that have the right receiving equipment. This system has proved to be more practical than induction since it can work from up to 3 feet away. Energeous wants to make a wire free charging ecosystem by taking into advantage the fact that the transmitter can charge multiple devices at a time, and as WIFI it would be able to charge your phone even if you are Samsung and the transmitter is Apple. All kind of devices can be charged using WattUp including (but not limited to) cameras, smartphones, tablets, wearables, and toys.

The receiver uses multiples antennas to collect the micro energy beams created by the transmitter (which makes it safe because power is received in small amounts). There is also an application available in which you can control the devices that are receiving power, how much power for each one, and even what times you want it charging. For example, you can prioritize cellphone charging in peak hours of use and leave other electronics to charge at night just with the click of a button.

The WattUp has already been FCC (federal communications commission) approved, and Energeous offers a variety of prices depending on the range of the transmitter, but it is still not available in the market. The company will be in CES 2018 showing their product, this event will take place on January 9th– 12th in Las Vegas.

Wireless charging not only benefits consumers, but also offers real benefits in terms of efficiency, productivity, and safety in industrial applications. Moreover, cables require maintenance and are easily damaged which makes them unreliable and expensive to maintain. In hospitals there is a constant need for big equipment that uses battery packs or cables, but to maintain a sterile environment WattUp could be a good alternative. Furthermore, in the future this technology could be used to power electric cars avoiding the need for charging every 10 to 40 miles.

[Source]

Cars getting into the customizable IOT game with AutoPi

Posted on by Maria Alejandra Escalante

AutoPi.io Dongle

Automotive industry has noticed the growing trend of internet of things and used it as a business opportunity for connecting their cars. By 2020, 381 million cars are expected to be on the road. Even when you can buy a IOT car there are few or none customization opportunities which is what differentiates AutoPi from other systems. A group of software developers created a device called AutoPi dongle based on Raspberry Pi which allows the user to fully customize their car which could change the way you drive.

Autopi is built on RSA and AES encryption to ensure total security and efficiency. The infrastructure is based on SaltSack and the device is based on the Raspberry Pi. The AutoPi dongle has WIFI, GPS, Bluetooth, HDMI out, 3G/4G connectivity, USB, accelerometer and much more. Additionally, they created the AutoPi cloud which allows remote monitoring, alerts, triggers etc.

Any external device can be connected to the AutoPi dongle to achieve much more. Some projects that have already been implemented include crash detection, collision prevent assistant, theft detection, parental control and video evidence recording. With the GPS and the historic trip widget included in the software you can know where your car was at any time.

It’s a perfect device for young new drivers and their worried parents who want to keep track of their kid’s speed, use of seatbelt etc. using a variety of sensors, all this information could be accessed remotely. Also, during summer the is nothing worse than getting into a car that has been left out in the sun. Hot weather can also shorten your battery’s usable life, and it’s a hazard for pets left in the car. Heat monitoring can detect the temperature and lower the windows slightly to prevent the temperature from rising too high, or during winter the car could be heated before you arrive. You can trigger an internal system, an external system, and an externally connected system in order to bring your projects to life.

For 94,5 € you can get the DIY edition, for 189 € the WIFI only edition, and 4G for 247,5 €. In the webpage you can also get the Raspberry Pi 3 adapter. The price is still a bit too high for a car accessory, but when you think about the possibilities and the improvement in your car and your lifestyle it is not that expensive.

[source]

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