Tutorial – MicroLipo and MiniLipo Battery Chargers @ The Adafruit Learning System.
Sooner or later you’ll need to cut the cord…the power cord! Untether your electronic project from the tyranny of the wall adapter and take it out into the world. That’s where batteries come in, and you may have been seduced by the high power density, large current capabilites and recharge-ability of Lithium Polymer or Lithium Ion batteries. These battery chemistries have quickly become the most popular rechargeable batteries in consumer products, powering everything from keychain mp3 players to huge laptops.
Tutorial – MicroLipo and MiniLipo Battery Chargers - [Link]
by Ken Shirriff:
Disassembling Apple’s diminutive inch-cube iPhone charger reveals a technologically advanced flyback switching power supply that goes beyond the typical charger. It simply takes AC input (anything between 100 and 240 volts) and produce 5 watts of smooth 5 volt power, but the circuit to do this is surprisingly complex and innovative.
Apple iPhone charger teardown - [Link]
The Joule thief is a really fascinating circuit, simple yet very intricate. Basically, it’s a step-up converted in its most elementary expression. I will spare you the theory since there is plenty of information on it on the web; rustybolt.info is a good place to start.
Joule thieves in all sorts of forms have been featured countless time on DIY websites and I felt it was time I build one. However, I did not want to leave the circuit at the breadboard stage because as it stands, the joule thief has characteristics that make it very attractive for all sorts of low power applications and I figured a flash light would be a very good home for a joule thief, where having the option of using dead batteries is certainly a big plus not to mention using less cells because the circuit steps the voltage up. Why dead batteries? Because a battery is never really dead, its voltage just falls down logarithmically until it hits a point where the device it was powering up stops functioning, which does not mean the battery is totally drained but rather that its voltage has fallen below a usable level. Since joule thieves are step-up converters, they can take that “dead” battery, and give it a new life by stepping up its output voltage to usable levels again.
Maglite Joule thief - [Link]
Stanford researchers, lead by electrical engineer Ada Poon, are working on midfield wireless power for medical implants, ranging in application from nerve stimulation to medication delivery. [via]
Midfield Wireless Power for Implants - [Link]
By Tahar Allag, Wenjia Liu:
Cell phones are a good example of how functionality and performance have both increased significantly in portable devices over the last few decades. They have become more complex and can do many basic tasks as well as any computer. The extra functionality that has transitioned the smartphone from a phone-call-only device to a multipurpose portable device, which makes it more power hungry than ever before.
The internal battery pack is the main source of storing and delivering power to portable-device circuitry. Batterycharger ICs are responsible for charging the battery pack safely and efficiently. They must also control the power delivery to the system to maintain normal operation while plugged in to wall power. The battery pack is required to store a large amount of energy and be charged in a short amount of time without sacrificing weight and volume. The increased charge and discharge currents, as well as the smaller physical size, make the packs vulnerable to physical and thermal stresses. Therefore, battery chargers are no longer required to perform just as a simple standalone charger
AppNote: Battery charging considerations for high-power portabledevices - [Link]
Designers of rechargeable battery-powered equipment want a charger that minimizes charge time with maximum charge current by maximizing the power taken from the supply without collapsing the supply. Resistances between the supply and the battery present a challenge. This article explains how to design the charging circuit to achieve the maximum power from the adapter despite the undesired resistances between the supply and battery.
AppNote: Extract maximum power from the supply when charging a battery - [Link]
One, tiny Dart. Power for all your devices. Perfect for your mobile lifestyle.
The Dart is the world’s smallest, lightest laptop adapter. At a powerful 65W it is a perfect complement to today’s thin, lightweight, portable laptops. It fits in a pocket and is designed with a USB port and single outlet profile to make it easy for you to stay charged up when you’re on the road. We hope you are as excited about the Dart as we are and looking forward to finally carrying just one, tiny Dart to charge all your electronics. Join our campaign and never be stuck powerless again!
Dart: The World’s Smallest Laptop Adapter - [Link]
by Michael Dunn:
Most electronics today requires multiple supply voltages – four or more rails is not uncommon. But if you’re using multiple, unsynchronized DC-DC converters, you’ve not only got a sub-optimal design, you’re asking for trouble. This Design Idea solves both problems.
Why trouble? I have firsthand experience of multiple power frequencies used in a system which also included sensitive analog electronics. Under certain conditions, difference frequencies (e.g., 10kHz, if one switcher was running at 250kHz, and another at 260kHz) would show up in high-impedance analog sections. Not good.
Avoid problems with multiple DC-DC converters - [Link]
A group of Korean researchers have turned their focus on supplying a reliable, efficient power source for wearables. Professor Byung Jin Cho of the Korea Advanced Institute of Science and Technology (KAIST) and his team, recognizing that supplying power that is stable and reliable is critical to the successful commercialization of wearables, have come up with a wearable power band that made technology news this week. The team noted that a flexible thermoelectric (TE) power generator would be the way to go to realize a wearable self-powered mobile device. They developed a wearable band-shaped item that produces electricity from the heat of the human body, The device size is 10 cm x 10 cm. Wearable electronics must be light, flexible, and equipped with a power source, which could be a portable, long-lasting battery or no battery at all but a generator, according to a KAIST release on Thursday, providing details about their work.
Power arm band for wearables harvests body heat - [Link]
By European Editors:
Military and aerospace, where rugged operation and reliable performance in a confined, hostile environment are paramount, have long been the most dominant markets for thermoelectric energy harvesting. Typically, thermoelectric devices exploit heat from engines and motors and use it to power sensors and wireless sensor networks for condition monitoring applications. Recent innovations are generating growth in this sector, as well as in allied sectors.
This article will review some of the major avionics and aerospace applications that use thermoelectric devices. For example, commercial and military aircraft incorporate sensors and sensor networks powered by thermoelectric generators to monitor the aircraft skin for damage that can cause stresses and structural weakness. In the aerospace sector, the Mars Rover, Curiosity, Galileo satellites, New Horizons space probes, and Cassini spacecraft are all TEG users.
Typical devices that will be considered include the CP range of TEGs from CUI, and the eTEC modules from Laird Technologies. Further consideration will be given to the management of energy generated by TEGs, with reference to the LTC3108 DC/DC converter from Linear Technology.
Thermoelectric Energy Generation Takes Flight for Aircraft and Spacecraft Monitoring - [Link]