June 30th, 2009

LiIon Battery Charger

LiIon Battery Charger

Even though not much information is published about Lithium Ion Batteries, we find them more and more often powering our portable electronics. While their price sometimes can go pretty high, LiIon batteries offer higher capacity from less weight and volume and faster charging. Laptops, portable media players, cell phones, cameras, etc. almost all use the LiIon so there is a very high probability to recover the battery from a damaged device and this way get all the advantages at a small price.

Like with other batteries, inside the LiIon type there are one to four cells connected in series, each at about 3.6-3.7V. Higher capacity is obtained by connecting series groups of cells in parallel. All is nice though until the battery gets empty, then the tricky part starts. Conventional chargers don’t work on LiIon and can even destroy them. There are some generic charges on the market but either they’re very expensive or they’re for small batteries.

Newer batteries communicate with the charger telling the settings to be used for charging. Even older batteries have a thermistor that monitors temperature and a protection against complete depletion. This being said, in this project is presented a DIY solution for a LiIon Battery Charger. There are some things you must know about the battery so that you can safely charge it.

First of all you must know the pin-out, you risk damaging the battery and/or charger if you connect it the wrong way. Then you must know the number of cells but you can determine this by dividing the battery voltage rating by 3.7V, you must also know the capacity and thermistor value. The charge current can vary between half and full capacity rating, the lower value the safest but the slower.

The charger presented in the link is based on application note AVR450 from Atmel. The project uses the AtMega8 microcontroller and it  features adjustable charging settings as well as Smart Battery Interface. Schematics and code for the Atmel are available as well as information on how to operate it. Good luck!


LiIon Battery Charger: [Link]

USB Bus Pirate

The USB Bus Pirate is a great project that can be used for testing new chips without writing any code. It is a universal serial interface device that is connected to the PC using the USB port.  The Bus Pirate currently supports serial protocols such as 1-Wire, I2C, SPI, JTAG, asynchronous serial and also has many other various features including PWM, frequency and voltage measurement, bus sniffers, pull-up resistors, and switchable 3.3volt and 5volt power supplies. The device receives commands from the user via a serial terminal.

The brain of the Bus Pirate is the PIC24FJ64GA002 microcontroller from Microchip, which is powered by a 3.3volt regulator. The programming pins are connected to a five pin header located on the lower edge of the PCB. The Bus Pirate is powered using the 5v supply at the USB port which is filtrated using a ferrite bead and a capacitor. The USB to serial connection is done using the FT232BL USB UART chip from FTDI.

The device possesses both 3.3v and 5v switchable supplies that are deactivated by default until a command is given. The circuit can be reset from software if needed. Also, the Bus Pirate has a CD4066BC quad bilateral switch that gives control over multi-voltage pull-up resistors, four voltage dividers connected to A/D converters which enable the pic to measure up to 6v DC, and three LEDs for power, mode, and voltage regulator status located on the upper side of the PCB.

The latest firmware of the Bus Pirate contains a modified bootloader from Microchip, so the firmware can be upgraded using the USB or the serial connection. A detailed procedure of upgrading is available in the link, as well as parts list, pictures and schematics. The Bus Pirate is available for purchase from Hackaday with worldwide shipping at $30.

USB Bus Pirate: [Link]

June 26th, 2009

DIY Holy Toaster

Diy Holy Toaster

Hallelujah, brothers and sisters! Praise the Lord! How many times have you thought you don’t have enough holiness in your life? How many times you wished you’d do more than just saying Grace before dinner? Well, now you can do something about that! Yes, with the help of the Holy Toaster, you can turn every meal into a God-worship ritual. Forget going to church! Holy Toaster is the s***!

This is an open source project that will transform your common toaster into a sacred device – a Jesus toast maker. Using two stainless steel inserts that block the toaster’s radiation in certain areas, your usual toaster will now have the bread come out with the face of  Holy Jesus, The Son of God. It will improve your daily meals and will bring godliness closer to you with every bite.

As mentioned in the title, this is a Do-It-Yourself project and for those who own or may operate a laser cutter it is fairly simple to upgrade their toaster into a divine toaster because the SVG and DXF files are available for download and free for use with any purpose or profit. Godly. Now you can impress your grandma when she comes visit.

For others that wish to have their breakfast enlightened by Lord Jesus and don’t have a laser cutter available, there is still hope! If you live in the US you can purchase the Holy Add-on of Light. Foreigners will also be able to order it the near future. Careful with the sharp edges and with the pliers when you install the holy inserts into the now holy toaster. And you’re good to go!

This project made me think of other things that could be upgraded with holy spirit. Like pasta in the form of a cross with a little Jesus on it or pizza with a big mozzarella cross and a Jesus made of salami. Possibilities are endless, really.

DIY Holy Toaster: [Link][via]

DIY Holy Toaster
June 24th, 2009

DIY Spot Welder

DIY Spot Welder

Used extensively in the automobile manufacturing industry for constructing the bodywork, spot welding is also seen in other various situations, like building PC cases or battery cells. A spot welder has the advantage of precise welding point and only heating the welding spot, so the rest of the materials remain cool and can be managed easily. Of course most of the welding done in an industrial environment is automated, but sometimes you may find yourself in need of a spot welder for personal use. Here’s how you can build one yourself using a microwave oven transformer.

The device uses two 4 feet heavy gauge copper wires to connect the transformer to the welder tips, a 12″ 26 wooden platform that acts as the base of the , two 7″ 22 wooden pieces which act as the “jaws” (only the  upper one is mobile), two corner braces to align and hold the welder’s jaws, two lugs which connect the copper wires to the welding tips and a bunch of screws. Care must be taken in aligning the mig welding tips to the right position, cutting the cooper cables to the right length and in stripping and mounting the welding lugs. The welder does not rely on high voltage, but on high current instead. After assembling all the parts, you should check electrical parameters with a multimeter.

With a fairly simple design and part list, this is a spot welder intended for small, personal projects like electrolysis cells or small robotic platforms. Remember to take precautions when handling such a device, as it uses high currents and generates high temperatures. You can find a detailed step-by-step presentation of the spot welder in the link below.

DIY Spot Welder: [Link]

DIY Spot Welder
June 23rd, 2009

Inside the iPhone 3G S

Inside The Iphone 3G S

June 19th marked the launch of Apple’s “fastest, most powerful iPhone yet”, the iPhone 3G S. Not sure what the S stands for (I’ve came across some guesses while surfing the web, speed, sex, sucks just to name a few), but according to Apple’s official website it should be “up to 2x faster” than the old iPhone 3G and should have a digital compass that reorients the map as you change the direction you’re facing, a 3.0 megapixel camera that can also record VGA video in 30 frames per second and voice control for calling and playing music.

On the outside, the new iPhone remains true to the traditional design of Apple – minimalistic, elegant and slim. As we unfold its shell, the new smartphone from Apple reveals a few interesting improvements. First, the PCB is more compact than before, with nearly every component on the top side of the board. Second, the CPU has changed – iPhone 3G S features the ARM A8 Samsung S5PC100 processor, which runs at 600Mhz with 32KB L1 cache memory instead of 412Mhz with 16KB cache like the ARM 11 Samsung S3C6400 used in the previous model. The new iPhone 3G S also features the PowerVR SGX graphics accelerator that runs at 200Mhz.

The smartphone has a Toshiba NAND flash memory and a new combo in the wireless department: the BCM4325 from Broadcom. It also received an important upgrade to the battery, from 1150mAH to 1219mAH, and it is rumored that the iPhone 3GS’ battery life will be 15-20 percent longer than the iPhone 3G’s. A great and necessary improvement for all iPhone 3G S users.

The most important upgrade of the new Apple device is clearly its Applications Processor Core. With a clock speed of 600Mhz, 256MB DDR SDRAM and the PowerVR SGX graphics processor, the new smartphone has the muscle to manage all kinds of demanding applications and, with the help of the SGX, that includes some serious gaming. The longer battery life also supports this idea and the iPhone 3G S might turn out to be quite a powerful mobile device.

Inside the iPhone 3G S: [Link]



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