Published:2011/7/25 2:28:00 Author:Li xiao na
No matter your budget is big or small, or no matter your application is forward or complex, you will never worry the above things, because the new DASYLab is developed to meet various kinds of demands. With this new software, the users will be able to enter the usability and make their data acquisition simple. Using the new software, the proce... (View)
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Published:2011/7/25 2:08:00 Author:Phyllis
The nRF905 transceiver and the nRF9E5 transceiver with MCU, ADC are launched by the Nordic VLSI ASA. The nRF9X5 components are designed for 430-950 MHz wireless transceiver applications in both industrial and domestic environments. Especially in security systems, wireless data transfer, automatic meter reading, car alarm systems, point-of-sale systems, sensors and various telemetry systems. The nRF9E5 and nRF905... (View)
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Published:2011/7/25 2:07:00 Author:Celina
随着互联网的不断普及,现在电子商务也取得逐步发展,而B2B无疑是电子商务中的主导模式。本文主要介绍B2B行业的盈利模式。 首先传统的B2B盈利模式主要有两种:付费会员制和网络广告。付费会员制即B2B网站的会员每年必须缴纳一定的费用才能享受网站提供的各种服务。这已成为国内B2B网站主要的收入来源。另一个就是网络广告。网络广告又可以划分为文字广告,图片广告,邮件广告,广告联盟等等。通过投放广告企业能获得更多的贸易机会。 但根据最新的研究报告,单一的传统B2B盈利模式早已不能满足平台的长足发展。特别是垂直型行业B2B网站受到会员规模的限制,正面临发展的瓶颈,为了突破困境,网站必须不断谋求新的盈利方式。现在新增的盈利模式主要有以下几个: 1.竞价排名:即客户通过搜索产品获得的排名,一般排名越靠前,企业也能获得越多的贸易机会。 2.增值服务:B2B网站通常除了为企业提供贸... (View)
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Published:2011/7/25 1:45:00 Author:Amy
By Benjamin Hinrichs Testing, testing, testing... and into the box Before inserting the microcontroller and the PGA2311 into their sockets and connecting the display, you should painstakingly check all the boards for incorrectly fitted components, dubious solder joints and solder bridges. The first test should be performed with the boards outside of the enclosure. To hold ... (View)
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Published:2011/7/24 22:54:00 Author:Amy
By Benjamin Hinrichs Stable supply A large part of the stabilisation, decoupling and hum suppression for the supply voltages takes place locally on the main circuit board, for both the digital portion (+5 V) and the analogue portion (5V). The only other thing you need is a sufficiently stable source of symmetrical DC voltages (which shouldn’t be a problem with the low current c... (View)
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Published:2011/7/24 22:52:00 Author:Li xiao na
By B. Kainka Inductors with cores RF inductor forms with threaded ferrite cores are often used in practice. The core increases the inductance, typically by a factor of four or even more. The inductor can be tuned by adjusting how far the threaded core is screwed into the inductor. Ferrite cores are made for specific frequency ranges, within which they exhibit small energy losses.
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Published:2011/7/24 22:37:00 Author:Amy
By Benjamin Hinrichs Channel switching The input channels are switched on the relay board. The circuit shown in Figure 3 allows two different wiring options. With the traditional option, all eight inputs from the Cinch sockets are used, with a single output to the main circuit board. This requires JP2 and JP3... (View)
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Published:2011/7/24 22:36:00 Author:Phyllis
The propagation of radio waves is a fascinating phenomenon because most of it is guessv/ork and sheer surprise. That is not to say the subject has not been studied extensively by researchers and radio amateurs — far from it, a number of underlying principles have been described in scientific terms as early as the 1920s by Nobel Laureate Sir Edward V. Appleton (1892-1965). Appleton discovered thai radio waves, depen... (View)
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Published:2011/7/24 22:29:00 Author:Li xiao na
By B. Kainka Electronics hobbyists often wish to copy a circuit for which suitable coils or fixed inductors are not readily available. However, you can wind just about any type of inductor if you only know how. Or you can take inductors from old equipment and modify or adjust them. All you have to do is determine is how many turns you need. (View)
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Published:2011/7/24 22:23:00 Author:Phyllis
Receiver sensitivity measurement With the generator tuned to the receiver (or was it the other v/ay around?) a great moment arrives — v/e’re ready to decrease the RF output level on the generator until the receiver under investigation loses the signal. The VHF-Low Explorer not having an adjustable squelch or squelch defeat switch, the transition from ’very noisy signal’ to ’muted’ was found to be... (View)
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Published:2011/7/24 22:12:00 Author:Phyllis
No receiver is complete without a matching antenna. Commercial offerings for the 4-m band being few and far between (or scrapped by PMR fleet owners), we decided to present a design for a low-budget get-u-going dipole. Not sophisticated, want a directional antenna? Then try the links at the end of this article. Too difficult? It doesn’t get much simpler than this, so give this antenna design a try and you’ll be ple... (View)
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Published:2011/7/24 21:30:00 Author:Amy
By Benjamin Hinrichs The multitude of options for constructing your ’personalised’ high-end preamplifier mean that you must read this second part of the article before you order the parts and take up your soldering iron. This is because your requirements determine how many circuit boards of which type you will need, as well as which components you will need. You can con... (View)
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Published:2011/7/22 4:02:00 Author:Li xiao na
A new and wide range of antennas are exhibited by Alpha Micro’s Special Products Division, which can be applied for home, mobile, firm, light, GPRS and so on. The new antenna has so many advantages, such as DECT and Bluetooth, single and dual band, 2.4 GHz. This new device is able meet all the demands from a large range of global factories and suppliers... (View)
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Published:2011/7/22 3:15:00 Author:Amy
by Paul Goossens Software PC software that can generate the necessary programming files and program them into the IC is required for pro-grarriming the CPLD. Fortunately, the manufacturer of the CPLD has a nice (and free) software package for this purpose (see Figure 6). This software is called Quartus, and it can be downloaded from the manufacturer’s website (http... (View)
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Published:2011/7/22 3:08:00 Author:Phyllis
By Benjamin Hinrichs The control centre The main circuit board, which forms the control centre for the preamplifier, requires surprisingly few components. This is due to the high integration density of the two ICs used here. By far the majority of the components are used to generate clean supply voltages. The circuit is split into an analogue portion and a digital portion... (View)
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Published:2011/7/22 2:47:00 Author:Phyllis
By Benjamin Hinrichs The PGA23I1 stereo audio volume control IC Admittedly, the idea of using a ’digital’ IC for volume adjustment, and further more controlling it using a microcontroller, may evoke a sceptical frown from many an audiophile. Ten years or more ago, this scepticism would certainly have been justified, but the semiconductor industry has made enormous... (View)
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Published:2011/7/22 2:29:00 Author:Amy
by Paul Goossens Experimenter’s board Our experimenter’s board has a reasonably simple design. Nevertheless, it has more than enough I/O for performing our initial experiments with CPLDs. Naturally, all of the relevant pins of the CPLD are brought out via several connectors, to allow external hardware to work together with the board afterwards. The schematic diag... (View)
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Published:2011/7/22 2:27:00 Author:Phyllis
By Benjamin Hinrichs The modern design of this preamplifiers yields audiophile specs, convenient operation and an attractive price. This is made possible by using a top-end digitally controlled attenuator/amplifier IC. Analogue audio electronics appears to have entered a dormant stage. In our present age of CDs, DVDs and MP3, traditional preamplifiers have been relegated to the role... (View)
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Published:2011/7/22 2:14:00 Author:Amy
by Paul Goossens Designing a circuit always involves several somewhat disagreeable tasks, such as soldering, looking up the pinouts of ICs and laying out a maze of tracks on a printed circuit board. All of this is now no longer necessary, since you can program your own digital circuit in a CPLD. Experimenter’s board features -CPLD version: EPM7128 -JTAG interface -all I/O lines... (View)
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Published:2011/7/22 2:12:00 Author:Li xiao na
by M. Conde de Almeida Construction The artwork of the PCB designed for the clock is shown in Figure 3. The PCB has to be cut in two to separate the main board from the display board. Start by soldering the wire links onto the main board. Then follow the five IC sockets and all low-profile components. The rest of th... (View)
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