Project Solutions

OPINIONS ON VALVES （3）

Published:2011/8/19 1:52:00 Author:Phyllis

The valve sound: myth or reality? By Klaus Rohwer, PhD That famous valve sound, does it really exist? Yes, it does — but it doesn’t have to come from a valve! Here we have to make a distinction between devices for producing music and devices for reproducing music. The first category includes music amplifiers(View)

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OPINIONS ON VALVES （2）

Published:2011/8/19 1:42:00 Author:Phyllis

By Bernhard Vollmer The valve microphone: physics versus emotions The author has been actively involved in quality assurance at Schoeps, a German manufacturer of studio microphones, for nearly two decades. As a supplier to Schoeps, his company Elvo makes the model M222 valve microphone (www.m222.de). What would music be without emotion? Should our experience, ears and sensit...   (View)

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OPINIONS ON VALVES （1）

Published:2011/8/19 1:29:00 Author:Phyllis

Valves versus transistors We have two audio amplifier design articles in this issue: one with valves and the other with transistors. They are just as different as people’s opinions on the issue of valves versus transistors. Does it make sense to go back to the amplifier technology of our grandparents? Is...   (View)

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AUDIO-TWEAKS from demagnetizing to varnishing （2）

Published:2011/8/19 1:15:00 Author:Phyllis

By Harry Baggen The activities the American company CyroPlus are less strange, and they also have a technical explanation. What they do is to chill interconnecting cables and speaker cables, as well as individual valves and ICs or even entire circuit boards, down to absolute zero. The idea behind this is that it restores the original crystalline structure of the materials i...   (View)

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AUDIO-TWEAKS from demagnetizing to varnishing （1）

Published:2011/8/19 1:06:00 Author:Phyllis

By Harry Baggen For true audio enthusiasts, nothing’s too far out when it comes to improving the sound quality of their hi-fi or surround-sound systems. Naturally, you can spend a lot of money on cables and other accessories, but there are a lot of possibilities that go even further, such as equipment modification...   (View)

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Bidirectional S/PDIF Converter

Published:2011/8/19 0:49:00 Author:Phyllis

By Joseph Kranz Although S/PDIF is the standard when it comes to conveying digital audio signals in consumer electronics equipment, difficulties may be encountered if you try to connect up two apparatus having digital connections. Cheap equipment usually has only one connection (coaxial or optical), while more up-market products will generally offer both variants. When interconnecting CD an...   (View)

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OPAMP TESTER

Published:2011/8/18 22:39:00 Author:Phyllis

Quick go/no-go testing for operational amplifiers By Dirk Scheumacher Not a microcontroller in sight, and yet this item of test equipment will be found very handy in any elect...   (View)

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Playful Lights: Just there LEDs...

Published:2011/8/18 21:46:00 Author:Li xiao na

By hubert Marwald Here’s a recipe to make LEDs produce slow, continuous light effects rather than abrupt changes normally obtained from square-wave drive signals. If you are after really accurate control of one or more LEDs, the best option by far is pulsewidth modulation (PWM) which is usually obtained from a dedicated PWM chip or a suitably programmed microcon...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 7

Published:2011/8/18 2:49:00 Author:Amy

Stefan Tauschek Spatial multiplexing Antenna diversity is aimed exclusively at improving results at the receiver end, and it can be used even if the transmitter end has only one antenna. However, if multi­ple antennas are used al both ends of the path, even more refined technical tricks can be used to i...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 6

Published:2011/8/18 2:42:00 Author:Amy

Stefan Tauschek MIMO Increasing antenna gain by a few decibels is by no means the only trick that can be conjured out of the magic box of RF technology Multiple-input, multiple-out­put (MIMO) technology is also proposed as a means lo significantly increase range and data rates without increasing RF power. What lies behind this name is a sophisticated antenna technology called ’p...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 5

Published:2011/8/18 2:35:00 Author:Amy

Stefan Tauschek More bandwidth This means we need more bandwidth and more chan­nels. The standardization committee satisfied this need in 1999 with the introduction of the 802.1 la standard. It utilizes the 5.8-GHz ISM bond and employs a modulation technique called ’orthogonal frequency division multiplex­ing’ (OFDM). This yields o raw data rate of 54 Mbit/s, although the...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 4

Published:2011/8/18 2:26:00 Author:Amy

Stefan Tauschek Wireless local area networks Now that you understand the techniques described above, we can enlighten you a bit regarding the vari­ous types of wireless networks currently in use. As can be seen in Figure S, frequency hopping is the tech­nique used by (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 3

Published:2011/8/18 2:16:00 Author:Amy

Stefan Tauschek Code Division Multiple Access (CDMA) With the DSSS technique, frequency spreading is achieved by modulation using a pseudo-noise signal. This signal is also called the ’PN code’, since it identifies an individual transmitter just like an identification code. The information signal can only ...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 2

Published:2011/8/18 2:08:00 Author:Amy

Stefan Tauschek Spread-spectrum techniques This problem can be solved relatively easily by taking a peek at the techniques used by (he military and copying their well-proven strategies. The magic word here is ’spread spectrum’, which amounts to modulating a nar­row-band information signal in order to significantly increase its bandwidth while at the same time consider­ably r...   (View)

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Wireless Connectivity: ISM, WLAN, WMAN, Bluetooth et al. 1

Published:2011/8/18 1:57:00 Author:Amy

Stefan Tauschek Wireless data communication is the latest rage. From wireless mice to Formula-] telemetry systems, digital radio systems are used in many applications, and they are penetrating into many new areas. In this article, we examine the current state of affairs in the ’airwave jungle’. The enormous popularity of wireless communication is a direct consequence or internation...   (View)

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Elektor Junior Computer

Published:2011/8/18 1:23:00 Author:Li xiao na

By Jan Buiting Although the Elektor Junior computer was not the first home-built computer based on the 6502 processor (the KIM and others having achieved spectacular results in the USA) it did become a legendary design with PCB sales in the thousands. The original Junior Computer v/as designed b...   (View)

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Power-Outlet LAN: In-home power lines carry audio and data

Published:2011/8/18 0:59:00 Author:Li xiao na

Jan Bulting Mains (or ’power-line’) signalling has matured from the early stages of the single 130-kHz carrier with simple modulation for a primitive 1-channel on-off control. Today, off-the shelf equipment is available that allows you to use the mains wiring and power outlets in your home or office to convey ...   (View)

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Intelligent Clap Switch: manual remote control with extras （2）

Published:2011/8/17 22:42:00 Author:Li xiao na

Jorg Prim Software When the signal level at GP1 goes low (clap detected) the program waits for approximately 200 ms during which time the LED glows red. After this period the LED switches to green and the software samples the input for approximately three seconds. If a second clap is detected during this period, the (View)

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ANTI-NOISE （2）

Published:2011/8/17 22:36:00 Author:Phyllis

If passive ear protectors, such as earplugs or closed headphones, are combined with active noise compensation, noise in the frequency range from 25 Hz to 500 Hz can be attenuated by more than 25 dB (Figure 5). The total effect of active and passive noise compensation is around 30 dB over the entire audio spectrum. Closed systems are particularly suitable for aircraft with a high noise level in the ...   (View)

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ANTI-NOISE （1）

Published:2011/8/17 22:20:00 Author:Phyllis

The sound of silence Noise has a serious impact on the environment as well as on human beings. Besides classical sound reduction techniques such as insulation, researchers are trying to attack the root of the problem using electronic means. They have already had some success. Sometimes it happens that an underlying physical process is well understood on paper, but the job of trans...   (View)

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