Perhaps the most frequently used rechargeable batteries on the market nowadays – Lithium-Polymer (Li-Po) can be found also in our offer.
From the beginning of electronics, the world searches for an “ideal” rechargeable battery. So far such a battery doesn´t exist (maybe supercapacitors in the future), but Li-Po (Li-Pol) cells are quite near to an ideal in some aspects.
Very low self-discharge (approx. 5% / month), high voltage of a cell (3,7-3,8V average), high energy density and a low weight, considerably stable discharge voltage and a possibility to recharge anytime are one of the main advantages of Li-Po cells. Another benefits are advantageous flat shape, high variability in dimensions and a long lifetime. No wonder, that Li-Po cells have become no. 1 in consumer electronics, hand tools and in many industrial devices.
Perhaps the only drawback of these cells is their lower chemical stability at overcharging (in a corner case ending up with a fire). But that´s the case which is practically eliminated at a common operation with a suitable charging circuit (chip or a charger intended for Li-Po).
Basic principle at usage is not to exceed approx. 4.25V charging voltage and the battery is almost discharged at a voltage below approx. 3.0V (2.75V). On the very end of a discharge cycle, the inner resistance slightly increases, what can cause a slight heating of a battery at higher currents – it is a normal behavior. Charging is usually based on a method constant voltage/ limited current. In principle it´s possible to use the same chargers and charging circuits for Li-Ion as well as Li-Po cells.
At a usual usage and discharging to say 20-80%, Li-Po cells will reward you by a reliable operation and a long lifetime. Flat shape is ideal for various handheld equipment, as well for usage in flat enclosures. In respect to a low self-discharge it´s possible to use Li-Po cells even as a backup energy source.
In our offer can be found several several Li-Po types from company EEMB with a capacity of 130 mAh to 2000 mAh. Exact list of available types and datasheets can be found below this article. Upon request, we´re able to provide you also many other types.
Try the most favorite type of batteries - [Link]
Ralph Doncaster writes:
Several months ago I noticed the Attiny88. It has several more I/O than the Atmega328, with an extra Port A and PC7. And unlike most of the other Attiny series, it has real SPI instead of USI, so libraries using SPI don’t have to be re-written. At just 86c for qty 1, it is the also the cheapest AVR with 8KB flash. Since QFP-32 parts aren’t easy to work with, I searched for breakout boards and found QFP32 to DIP32 boards that would allow me to use them in a small breadboard.
Breaking out a QFP Attiny88 AVR - [Link]
by Kathy Yang @ elecfreaks.com:
ElecFreaks will launch a multi-axis unmanned helicopter series: ELF. As the name suggests, this series will be surprisingly tiny. Aimed to design a very compact, portable, able to fly in any place multi-axis helicopter, we will use smart phones app (must support Bluetooth 4.0) instead of remote control. Smaller also means more security and therefore would be more suitable for various occasions and people. If you are a child, this helicopter will be like any other toy of yours. Like always, we will open source all the information. If you are an advanced gamer, this helicopter will be perfect for research and development. If you are just a junior gamer who don’t care details that much, it’s totally ok, ELF got novice mode to allow press-one-key takeoff.
Drone ELF First Successful Trial Flight - [Link]
by Boris Landoni @ open-electronics.org:
Since when white light emitting high brightness LED are available, the handover from traditional lighting bulbs to the solid-state lighting has become irreversible: LEDs have an efficiency (expressed in lumens/watt) higher than that of almost all the traditional lamps (except, at the moment, the large sodium vapor lamps used for street lighting, unusable in closed environments for the high power required and the chromatic aberration they produce) at a cost that is today less prohibitive than it was a few year ago. They are indeed very sturdy and have a very acceptable ratio of luminous flux and size.
The perfect Remote, Programmable, Controller for interactive LED strips - [Link]
An all-in-one, water and sand resistant, solar charger, audio speaker system, and sunburn timer calculator by starwisher. Check out the project’s instructables page here:
This Instructable harnesses the power of Arduino, a UV sensor, and simple mathematics to make one nifty gadget sure to boost your outdoor summer fun – and minimize your indoor summer recovery!
Beach Buddy, a 3-in-1 solar phone charger, boombox, and sunburn timer calculator - [Link]
by Edwin Chen @ open-electronics.org:
The model of this shield named Yun Shield, the feature of this shield is as its name. User can add this shield into Arduino (Leonardo, UNO, MEGA2560 etc) and “turn” the Arduino into device which has similiar features as Arduino Yun: support remote upgrade and use the Bridge library.
With this shield, user can easy to set up communcation between Arduino and Internet (via ethernet , wifi or 3g etc) and add support for USB flash, video. The detail user guide/ manual can be found in the dragino website and most Arduino Yun Sketch / examples can reuse with this Shield. This shield is under production and will be ready within one months time.
Add Linux, WiFi, Ethernet and USB to Arduino - [Link]
Kyle wrote an article detailing his DIY automatic water timer:
Now that I have power and output figured out, I need to work on the control aspect. 555 timers are great for simple applications requiring up to a few minutes of delay. At 10 minutes, the RC values needed would boarder the danger zone of the timer not functioning correctly due to the leakage current of the capacitor and the small charge current of the resistor. I could have cascaded two or more timers together but that would be sloppy so I fell back on my trusty friend – the ATtiny micro controller. This would allow me to make changes as I want without redesigning the board.
DIY automatic water timer - [Link]
A simple temperature control system for 3D print or other constant temperature control purpose by Xiang:
I plan to build a home-made 3D printer controlled by my Raspberry Pi, which, unfortunately, does not have any analog data acquisition pin. Therefore I decide to build a stand-alone temperature control system.
The idea is very simple. I use a power resistor as the heater and a thermistor as the temperature sensor. The system contains an LM324 quad op-amps chip. One op-amp is used as a comparator to compare the thermistor resistance with a nominal resistance and output LOW or HIGH as the comparison result. The other three op-amps inside the LM324 are used to perform some linear transformation and output a voltage that is proportional to the thermistor temperature. This voltage is applied to a 0-30V voltmeter so one can read the temperature. A N-Channel MOSFET transistor is used to control on/off of the heater.
Simple temperature control system - [Link]
Jianan Li made this LiPo Booster project, that is available at Github:
LiPo Booster is a breadboard-friendly boost converter board based on the TPS61230 IC from Texus Instrument. It has an output voltage of 5V, and is designed to be used with a single cell LiPo battery.
LiPo Booster, a breadboard-friendly boost converter board based on TPS61230 - [Link]
by BABU TA @ edn.com:
This flasher/beacon circuit can be employed as a distress signal on highways, a direction pointer for parking lots, hospitals, and hotels, etc. The circuit uses a power LED, and provides more light than a typical incandescent lamp flasher. Use of a 6V or 12V SLA lantern battery makes the circuit portable.
HB-LED flashing beacon repurposes switching regulator - [Link]