by Susan Nordyk @ edn.com:
Furnished in a ceramic surface-mount package that is just 3.2×1.5×0.8 mm, the RV-8803-C7 real-time clock module from Swiss manufacturer Micro Crystal consumes 240 nA and operates from a supply voltage as low as 1.5 V to increase the life of backup supplies. The device gives designers the option to replace expensive batteries and supercapacitors with low-cost multilayer ceramic capacitors for battery backup.
The temperature-compensated real-time clock is accurate to within ±3.0 ppm (±0.26 seconds/day) over a temperature range of -40°C to +85°C. In addition to low current consumption and high accuracy, the RV-8803-C7 has one of the smallest ceramic packages in the industry with an integrated 32.768-Hz quartz crystal. It operates from a supply voltage ranging from 1.5 V to 5.5 V and employs an I2C interface.
Tiny real-time clock consumes only 240 nA – [Link]
And it can be added that also simply and cheaply. MCP73831 from company Microchip is „all-in-one“ solution for charging a single Li-ion/Li-Po cell.
Li-Ion a Li-Polymer cells are becoming a No.1 choice for many applications, where they persuade by high energy density, low weight, low self-discharge and for majority of applications also by their favorable flat shape (Li-Po). Their price is also affordable (in regard to their properties) and so there´s usually only one “difficulty” – to solve charging, or more exactly – overall management of these cells. Basic principles were highlighted to you in our article “Try the most favourite types of batteries”. To reach a maximum cell lifetime, it´s also advisable to use initial (preconditioning) slow charging and also important is a proper charging termination as well as repeated recharging after reaching a certain degree of discharge.It´s obvious, that to construct such a circuit from discrete components would be possible, but impractical, bulky and expensive. That´s why there are various charging controllers on the market and in many cases a single chip solution is an ideal solution. This is also a case of MCP73831 chip – a fully integrated linear charging controller. If you use only a single cell and maximum charging current of 500mA is sufficient for you, then MCP73831 will meet all requirements for a quality and safe recharging solution. MCP73831 has integrated output (FET) transistor, current sensing and reverse discharge protection.
Charging current can be easily adjusted by a single resistor, what´s also associated with other parameters like preconditioning current and charging termination. MCP73831 also contains a thermal regulation, which decreases output current in case of increased chip temperature (for example because of higher ambient temperature).
MCP7383x is available in four versions with factory-set regulation (max. charging) voltage. In our store can be found “the safest” first version with 4.20V regulation voltage – MCP73831T-2ATI/OT. In datasheet (p. 25) we can also read that this is the “AT“ version, which starts repeated charging at 94% Vreg (i.e. at approx. 3.95V), in a SOT23-5 package. Supply voltage can be in a range of 3.75-6V, while in respect to a thermal stress of a chip it´s better to supply it by a voltage close to max. output voltage (4,20V).
The chip can be easily supplied by a standard 5V voltage, but in cases of increased risk of overheating (operation at higher ambient temperatures, densely populated PCB,…), a common Si diode in series can be helpful. This will decrease supply voltage in 0.6-0.7V (and takes a portion of thermal loss on itself).
Charging status can be found at the “Charge status output” pin, which can drive an indication LED or can be connected to a host microcontroller.
With MCP73831 you’ll charge lithium cells easily and safely – [Link]
This circuit is built to repel mosquito using high frequency sound. The design is comprised of LM555 timer which provides the pulse generation and precision timing. It is also a stable controller capable of monostable or astable operation. The 74HCT4017BQ device is a Johnson decade counter with 10 decoded outputs. It provides the signal to be fed into the 555 timer which is connected to the output piezo speaker. The piezo speaker generates the sound. The Bipolar Junction Transistors(BJT) BC337 and BC327 acts as the amplifier of the output sound. It forms the push-pull amplifier that is more efficient than a single-ended Class A amplifier.
Electronic Mosquito Repeller – [Link]
This is a prototype model Battery (type C ) for electronic devices. The battery has the ability to be recharged by the sun and don’t need any battery charger. It is necessary for climbers, explorers, soldiers, free camping and general for humans who attempt in areas without infrastructure electricity. The standard can also be applied to other types of batteries and the current technology allows their development with much greater energy capacity.
Specifications of the prototype:
- Battery 1.2v 700 mAh
- Solar cell 1.5v 70mA
Solar self-rechargeable Battery – [Link]
by PiJuice @ instructables.com:
I’m so excited about this new project! A truly compact and portable Raspberry Pi Camera and it’s easy as anything to build!
I first thought about building a Raspberry Pi Camera after seeing the SnapPiCam instructable guide. This is a clever little project, which uses a LiPo battery to power a Raspberry Pi model A. But it got me thinking could I do something even more compact which is even simpler to build?
The real challenge is powering this little baby. Where the SnapPiCam is using a separate battery, converter and charging unit I’ve used the PiJuice. It’s basically an all in one battery module for the Raspberry Pi and it’s an ideal integrated power solution for a DIY Compact Camera.
I’ve also decided to use the Raspberry Pi a+ as it’s the cheapest and smallest available Raspberry Pi so it’ll fit nicely with PiJuice and make this camera supper compact!
Raspberry Pi Compact Camera – [Link]
by LoganP2 @ instructables.com:
The GPS tracking device is composed of a microcontroller, GPS module, cell module, and batteries all housed in a 3D printed case. The microcontroller is programmed to communicate with both the cell module and GPS module. When the GPS module is not within a user-specified boundary, the device will send a text message alert. We made a device that can track people suffering from Alzheimer’s and Dementia could greatly benefit the quality of life of both that person suffering and the caretaker.
GPS Tracker for Alzheimer’s Patients – [Link]
Series of enclosures CEMxx in versions for horizontal and vertical PCB placing offers wide possibilities of usage.
17,5 mm/ 22,5mm but also 35mm – in these width is available well-proven series of DIN-rail enclosures Euroclamp CEM17, CEM22 and CEM35, which was introduced to you in our article Gain more space on the DIN rail with housings Euroclamp CEM22.
Enclosures are delivered “complete”, i.e. including a Din rail holder and the top cover. The only, what´s necessary to buy (depending on a target application) are connectors (terminal blocks) labeled as ML25x, i.e. ML252, ML253 and ML254 or PV02 pin headers (PV03, PV04) dedicated for SH02 plug-in connectors (SH03, SH04).
Novelties in our offer are terminal blocks ML253-5-D-LI and ML253-5-S-LI suitable for CEM35 enclosures. From recent types of the ML253 series they differ only in somewhat longer pins (to be soldered into a PCB), what enables them to “lay” directly on a PCB (no need to make a cut-out for a connector).
Enclosureshave a UL 94 V-0 flammability and they are of a grey color RAL7035, other colors upon request. Upon request also imprinting and housings modification are available. Detailed information will provide you datasheets at particular types. Comprehensive overview of Euroclamp connectors and enclosures will provide you the Euroclamp short-form catalogue.
Euroclamp CEM – DIN rail enclosures for every PCB – [Link]
This design is a type of indicator that is used in voltage reading. It operates as an indicator rather than a meter that drives LED for voltage indication. Voltage thresholds are 1.5, 3, 4.5 and 6V. Above each incremental threshold an additional LED turns on.
LED DC Voltage Indicator – [Link]
As any beginner electronics hobbyist I have recently came to conclusion that using Arduino (or even Mega328) for small projects is neither cost-effective or educational (I’ll explain why later).
Another reason for writing this article is that I came across few ATTiny13A-SSU chips @ less than $0.90 each, which is even lower the official retail price, so I just had to buy 5 of them, although I didn’t know at the time whattahellamigointodowithit what is it really capable of.
Starting with ATTiny13 – [Link]