Monthly Archives: December 2015

Some Innovations That Can Change Life

The OrbSys green shower

Showers are great for morning ablutions, but people do not realize they may be harming the environment. A 10-minute shower could set you back by about 100 liters of water, while brushing your teeth and flushing the toilet could take up another 50 liters. Multiply by the number of people in your locality and you get overwhelming figures.

Concerned by this abuse of a scarce natural resource, designer Mahdjoubi addressed the problem with his patented design – the OrbSys Shower. Basically, the arrangement consists of a water purification system and a pump. When you take a bath, the system purifies the water, while the pump recycles it.

The advantage is reduction of water usage by about 90 percent, which means you consume as little as 15 liters every morning. Apart from reducing consumption, the filtering process also heats the water, which saves a lot of energy. As the system purifies to the specifications of drinking water, one is actually taking a bath in pure water. Imagine the value of the system in places that hardly offers access to clean water.

According to Mahdjoubi, it is about time people started making smart uses of the scarce resources of our Earth. He gives the example of astronauts in space stations, who have very limited supply of water they had started with from earth and must recycle every drop. In fact, Mahdjoubi drew inspiration for the OrbSys Shower from space stations.

Vein Viewer

Physicians and nurses often have to collect blood samples from their patients for a variety of reasons, for example, intravenous administration of drugs and more. Often, their attempts at locating the vein are not successful, leading to painful multiple pricks of the needle.

This procedure proves more painful and stressful to the patient if he or she is a child or an elderly person, because their veins are narrower as compared to those of a healthy grown-up. Additionally, for cancer patients who have undergone several cycles of chemotherapy, the veins tend to shrivel up, making it extremely difficult to locate the vein. The nurse may require 5-6 attempts at pricking before they locate the vein.

Vein Viewer makes use of an infrared camera to highlight the flow of blood and show the exact location of the veins under the skin of the patient. Since it projects the image in real-life on to the skin, finding the specific vein becomes very easy. Finding the vein is thus possible in the first attempt, making the process of collecting blood samples more comfortable and safe.

Power Plants that float

Whether thermal, hydroelectric or solar, power plants tend to take up a lot of real estate. This gave rise to the concept of power plants that float – not on water, but high up in the atmosphere. These high altitude power plant drones will harvest solar and wind energy, transmitting it back to earth wirelessly.

Although still a concept, the floating power plants are likely to be 20×20 m devices with solar panels on the flat surface and several wind turbines on the edges. Floating at a height of 50 thousand feet above ground, it can change its place to take advantage of uninterruptible solar and wind energy.

Selecting the Proper Brushless DC Motor

You may have an application that requires high-speed, but quiet operation with low EMI generation and long operating life. For such applications, BLDC or brushless DC motors are what you must be looking at. Among many advantages of these motors, high-speed operation is a special one. As there are no brushes or commutator in the motor, the bearing friction is the only factor limiting their rotational speed.

Absence of brushes and commutator also means there is no arcing within the BLDC motor to cause erosion or EMI. The last factor makes these motors suitable for use in RF applications. With windings on the stator, BLDC motors show superior thermal characteristics over conventional motors and are consequently more efficient. Because the stator is connected to the case, heat dissipation is fast. All such factors means a BLDC motor has virtually non-existent maintenance problems.

The major downside to all the above good characteristics of BLDC motors is their higher cost. BLDC motors can easily cost about twice as much as simple brushed motor and this puts the BLDC technology out of reach for many applications. Apart from the cost of the basic motor, there is the added cost of the control or drive electronics. If not integrated within the motor itself, you will need to find space for mounting the electronics outside, but nearby. You cannot separate the drive and the motor with long cables, as the noise introduced will cause malfunctioning.

A brushless motor also must overcome starting friction, just as brushed motors do. Again, starting friction does not depend on speed, but is the sum total of torque losses. Dynamic friction, proportional to speed, defines the torque losses in BLDC motors. Viscous friction in the ball bearings cause dynamic friction and eddy currents in the stator, originated by the rotating magnetic field of the magnet, adds to it. Nevertheless, the speed-torque curve of a BLDC motor demonstrates excellent linearity.

Directly connecting to a DC supply will not operate a BLDC motor, unlike a brushed DC motor. This is because brushless technology makes use of electronic commutation. Although there is no physical commutator or brushes, the operating principal remains the same, with the permanent magnet rotor initiating motion by chasing a revolving magnetic field induced by a current in the stator windings. A PWM or pulse width modulated signal is necessary to create the on/off signal, which actually creates the motion.

A comparator normally generated the PWM signal, which is a voltage generated because of a sinusoidal command signal superimposed with a saw toothed carrier or chopper frequency. If the command is greater than the carrier frequency, the PWM signal will be high. This is because the low chopping frequency gives the current more time to gain amplitude. The current density governs the rate at which the motor accelerates or decelerates.

To avoid ripples and a shortened motor life, it is important that the switching frequency is high enough. This is usually done by controlling the discrete on/off steps with six semiconductor switches. These send the amplified current through the correct phases, with the necessary switching being done by the semiconductor switches.

Researchers Create a Highly Sensitive Magnetic Sensor

Scientists at the National University of Singapore have constructed a new hybrid type of magnetic sensor that is more responsive that the existing varieties. This innovation holds promise for the creation of cheap and compact sensors and detectors in areas like information technology, electronics, health sciences and automotive industry.

Professor Yang Hyunsoo, who has directed the design of the device, has explained the findings in the September 2015 issue of the periodical Nature Communications.

Using the concept of magneto resistance

Just as electric resistance develops when an electric current passes through a conductor, a similar feature called magneto resistance comes into being when certain substances are placed in a magnetic field. Scientists at the university have utilized this newly discovered feature in developing the magnetic field sensor.

Although the feature is exhibited by all magnetic materials, the university team has been on the lookout for an ideal material, which would be particularly receptive to low and high fields, while remaining immune to temperature variations. In other words, the magneto resistance should vary appreciably with any change in the magnetic field but should be stable when the temperature changes.

Graphene and boron nitride combination

The scientists tried out several groupings of different materials. These trials led to a hybrid arrangement comprising graphene and boron nitride that suggests great potential as a sensing device. The team experimented with the material placed at various angles with the field and at different temperatures. According to Dr. Kalon Gopinadhan of the university, a two-layer structure of the two materials shows a sizeable response to small changes in magnetic fields. The researchers found that the hybrid structure was 200 times more receptive than sensors currently in use.

A significant gain of using this sensor is that the combination shows very high sensitivity at and around 127 degree Celsius, the temperature at which most electronics function. The sensor is small and can be easily fitted into other devices. Furthermore, the manufacturing cost of graphene is very low as compared to that for existing sensors made from indium antimonide.

Complying with industry requirements

The demand for reliable magneto resistance is expected to rise steadily. Indium antimonide sensors used in the automotive industry suffer a change in properties due to temperature changes caused by the air conditioning or the sun’s heat and do not function reliably. Cars and other vehicles use several sensor systems in interlocks, flow meters and position sensors that make use of complicated temperature correction circuitry to offset the errors. The new hybrid sensor eliminates the necessity of these rectification procedures.

Professor Yang declares that the graphene and boron nitride combination is prepared to take on the current sensors in the market. Apart from finding use in applications like hard drives, thermal switches and magnetic field detectors, they can be incorporated in flexible electronics, as well.

The university team has applied for a patent for the innovation. They now plan to scale up their production in order to turn out wafers of several sizes to meet the demands of the sensor industry.

Raspberry Pi and the Smart Video Car

As kids, nearly everyone has played with a battery-operated car controlled by a remote. Now, you can have the same with the Smart Video Car, but with vastly enhanced features. Additionally, you can control the Smart Video Car from your PC, because running the car is the versatile, single board computer, the Raspberry Pi, or RBPi.

You are in luck if you already have an RBPi B+ or the RBPi 2 with you, as the car comes as a complete learning kit, but without the RBPi. The car operates on 7-12V DC, supplied by two 18650 rechargeable lithium batteries. Since the RBPi cannot operate with such high voltages, a step-down DC-DC converter module is included. The module steps the battery voltage down to 3.3V, suitable for the RBPi to operate satisfactorily.

The kit contains all the multiple parts needed to put the car together. The driver module is based on the IC L298N, from ST Microelectronics, which works as a full-bridge motor controller. That means you can run the car backwards as well. To let the PC control the car wirelessly, the kit includes a USB WLAN stick or Wi-Fi Adapter. To know where your Smart Video Car is at any moment, you can check out the video it sends to your PC or smartphone through its webcam in real-time. The webcam is a part of the kit.

Using the PC, you have complete control of your Smart Video Car. Apart from forward or backward motion, you can turn the car left or right to avoid any obstacles in its path. An additional feature is you can control the camera independently to turn it vertically and horizontally. This way, you can capture the image from different directions.

SunFounder, the manufacturer, supplies all the necessary instructions, diagrams, descriptions and code in a complete manual along with their kit. A Tower Pro Micro Servo SG90 drives two front wheels of the car kit to make it turn left or right, while the other two rear wheels are active wheels. Two Gear Reducers drive the rear active wheels. A 12-bit PWM driver with 16 channels drives the L298N driver module for DC motor.

If you are just beginning to learn the RBPi code and application, this is a great kit to start. However, the kit also teaches you about basic components and modules in electronics. You can then use this knowledge for furthering your application and explore in different fields.

As SunFounder provides the entire code including all the necessary parts, anyone can assemble the kit referring only to the user guide. Building this Smart Video Car can be a fascinating experience and an enjoyable one. If you are running Linux on your PC, you can realize the car control very easily. You can even use Linux running on a virtual machine with equal ease.

The kit uses MJPG-streamer to capture images and transmit video in real-time. If you have a Firefox or Google Chrome browser running on your PC or smartphone, you can easily view the video on the browser and at the same time control the Smart Video Car.

Get 37 Sensors for Your Raspberry Pi

If you have a bunch of school kids rearing to have a go at the most popular single board computer, the Raspberry Pi or RBPi, then this 37-sensor kit is something that can keep them happy for hours on end. Fans of the open source RBPi will relish the different kinds of experiments they can try out with the funny and completed modules in this new kit.

The modules in the kit connect to your RBPi and send it all kinds of different signals from the physical world. Using these modules by connecting them to the RBPi is very simple as the manufacturer of the kit provides detailed information and usage guidelines for all the sensors in the kit.

The latest kit from SunFounder comes with the sensors neatly packed in a plastic box, along with the 168-page user manual. The improved Fritzing breadboard and the sensors are suitable for the RBPi Model B+ and RBPi2. The kit also contains the detailed material list of each module. Users get the improved code in Python and C along with the Fritzing images. That certainly helps the user to learn to use the sensors for their individual applications.

You must have your own RBPi for using the sensors in this kit, as the kit itself does not come with the RBPi. Moreover, the 40-pin GPIO expansion board included with the kit is for the RBPi B+. The most interesting part of the kit is the 16×2 LCD module and the Breadboard. Using these and the several sensors you can try out about 35 experiments listed in the kit.

The experiments cover a mixture of analog and digital electronics. For example, you can learn about how a relay works, how a mercury tilt-switch functions or how to make an active or a passive buzzer sound the alarm. Those interested in remote sensing will find the Hall sensor fascinating, along with the sound sensor and the gas sensor. With the Ultrasonic Ranging Module, you can easily measure distances without approaching the distant object.

For those interested in temperature measurements, there is the DS18820 Temperature Sensor and the Thermistor module. The RTC-DS1302 module will help in measuring in real time, while the Barometric-BMP180 and the Humidity sensor will help in determining or predicting the weather.

Experiments in light interest many. For them, the kit includes dual color LEDs, RGB LEDs, and Auto-Flash LED modules. Photo-interrupter modules, IR obstacle modules, IR remote control module and the IR receiver modules will help those interested in communication with light beams.

Control experiments that are more sophisticated are also possible. For example, those interested in Analog to Digital and Digital to Analog conversion and control will find the AD/DA Converter PCF8591 module to be useful. Other modules such as the Rotary Encoder module, the Joystick PS2 module, the MPU6050 module hold promises of still further sophistication.

The kit is suitable for all types of beginners, learners and the more initiated. It is an attempt to allow users to learn the basics of analog and digital electronics. Users can then move over to experimenting with different types of sensors and learn about controlling their physical world.