Remember those discussions about transmitting electricity wireless, they all concluded that it was just not efficient enough to be worth building such a system. Well it appears things have changed because in this video Eric Giler the CEO of MIT-inspired WiTricity, presents us with a new concept for transmitting electricity wireless.
It’s really interesting because they’ve manage to make the system small enough to fit on a mobile phone. He also states that WiTricity could be powering all of our devices into the future, like tv sets, home appliances and even electric cars. He didn’t touched the price subject though so I wonder how much would such a system cost.
Yet another car related project, this is the AVR J1850 VPW Interface which was designed as an On Board Diagnostic tool for car monitoring. The brain of the device is again the ATmega8 AVR microcontroller from Atmel, with 8KB of flash memory (this is more than enough for all kinds of features, since the basic source code is only 3KB).
The device supports serial RS232 for connection with the automobile, different baud rates (varying from 9600 to 115200 Baud), 4 different bus monitor functions and can handle header messages of 1 and 3 Bytes long. The circuit was designed for a single layer PCB and, starting with firmware 1.04, the device has a crystal 7.3728MHz. The controller is programmed using the ISP connector.
The interface has been tested with various ODB software, including Scantool.net, wOBD, Scanmaster and many more. A .pdf file containing the schematic, parts list, bill of material and other information regarding this project is available in the link below, as well as the source code, released under GPL.
Yesterday I wrote an article about an Atmel based Sony Unilink interface and today it’s another Unilink project, this time based on Becker car radios. For those who do not know, Becker is an important manufacturer of car radios and car navigation devices and it’s based in the UK. Becker made the first car radio, the first microcontroller car radio and the first car radio with CD player and has quite a lot of other achievements.
Becker’s version of the Unilink protocol is very similar with Sony’s in terms of hardware, but different in software. The good thing about this is that you only need a different connector and source code with Becker support. The model presented here is a Becker Monza 7882, a European model, with two DIN-ISO connectors and a Mini-ISO connector field (the picture above illustrates the pinout for this model, you will also find the complete pin listing and additional information).
The MCU used is the ATmega8 from Atmel and the schematics are available for download. The source code was written in C and is also available in the link below (there is a logger only version, an interface version and a modified source code for Becker Mexico 2330). The files are released under GNU General Public License.
Thomas Bethe built an audio hi-fi amplifier using two TDA2050 integrated chips. I haven’t seen these chips used in projects in a while, because it’s pretty known that TDA2030, TDA2040, TDA2050 chip family is not the best so to say. I remember some years ago, a local factory was building hi-fi amps using these chips and how often i needed to replace the destroyed TDA’s. Their Pentawatt package is not very good. These ICs are more suitable for TV sound amplification, radios, applications in which they drive some small full range speaker.
The speakers Thomas wants to use with his amplifier are a pair of Klipsch RB-51, which are pretty small and well behaved. In the TDA2050 datasheet it is proudly stated that the small chip can deliver 32 Watts RMS into 8 ohms with 10% THD. At this level of distortion those Watts are actually WHATS?! From graphs we can see it can actually deliver about 18W into 8 ohms and stay in the hi-fi area of 0.1% THD.
The schematic used is the split power supply version from the datasheet with an additional feature, headphone output. Thomas used a MKP capacitor at the input of the amplifier circuit. Although it’s always best to use high quality components, i wonder if any differences can be noticed with the TDA. The construction is pretty simple, just a few external components are needed but as the author says the layout is very important in reducing noise. So follow the advices he points in his article.
The amplifier is connected to +/- 25V supply rails, therefore it is not recommended for this amp to be used with 4 ohms loads. If you have low impedance speakers use +/-18V supply. Thomas’ power supply seems to me an overkill but i guess it does the job. If you plan on building this amp yourself screen the power supply and avoid crossing the wires carrying audio signal above power supply.
As far as how it sounds Thomas seems to be happy, even calls it a “mini gainclone”. To me the TDA’s don’t stand at the same level with National Semiconductor LM chips but it’s purely subjective opinion. Anyways anything you build by yourself is ten times better than what you find in the market for the same price as your investment so happy soldering.
The Sony Unilink protocol is usually meant to control the CD-player of an automobile and can also perform other various tasks. The Sony Unilink protocol can be used to connect other auxiliary devices to your car stereo (these devices vary from CD shuttles to iPods).
This project is an AVR Sony Unilink interface based on the Atmel ATmega8 microcontroller. The MCU runs at 7,3728MHz and the communication with the Unilink bus is made through Serial Peripheral Interface (SPI) and the software supports RS232 input and output. The source code was written in C and the files as well as schematics are available for download under GNU General Public License in the link below.
(Another Unilink interface project entitled GNUnilink, based on the PIC16F628 running at 10MHz is also presented under GNU License).
