Showing posts with label line. Show all posts
Showing posts with label line. Show all posts

Wednesday, December 18, 2013

the layout of the electricity line around cell phone jammers should be done

And some revise of the layout of the electricity line around  cell phone jammers should be done.
And mobile, China Unicom, not limited to the scope of telecommunications triple-play cell phone number to send, according to the specific needs of custom personalized service. Students as a distinct group, have higher education, higher information needs with the progress, contact television and other media opportunities, the phone reports that the new target audience. Campus mobile newspaper reading population is more focused and precise, and naturally become a new choice in the promotion of business products. Campus phone reported. Campus mobile newspaper "News" is the fundamental content. Planning Students mobile newspaper content loved by readers, of course, we must first understand the interest of the target audience of university students, according to their characteristics, needs.  Industrial environment: As the sponsor reasonable ease the demand for advertising, legal and mobile advertising services, so in fact played a large role in governance spam messages, thereby purifying the industrial environment, the industrial chain win. Status and Prospects of the development of mobile media. As information technology continues to progress, the original mobile phone as an interpersonal exchange of information intermediaries.
Rather to ensure that each piece of information, "Jane and deep." To do Jane and deep "will be a higher demand for editing, you need enough news sensitivity. Such as to make the correct interpretation of the country, the government introduced the policy of involving university students to study or work, and make predictable judgments, and even make incisive reviews, make the appropriate adjustments to help and facilitate college students to use the relevant policies give practical advice. Recommendations for mobile newspaper audience attention of contention. According to the spread scientist Melvin De Fule theory, when major changes occur, the audience will generate an exception to the media rely on. Which media can be timely and adequate to provide information to who he would rely on.  However, todays mobile newspaper is considered to be a subsidiary of the print media, the contents of the value of the performance of the force and the media not been fully recognized and mining. Information personalization. First of all must be aware, mobile newspaper should not just newspapers optional supplement. The mobile newspapers content to get out of the shadow of the newspaper, to form their own style and play their own unique advantages, mining the content of expression, and expansion of channel function.
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Wednesday, April 10, 2013

Automatic Night Light Feeds Directly From the AC Line

There are many approaches to the problem of activating a light when it becomes dark, and a recent Design Idea covers this topic (Reference 1). Some approaches require a dc power supply and an electromechanical relay, but a better approach involves feeding the device directly from the ac line, minimizing the number of components 

(Figure 1).


Figure 1. The photoresistor activates the TRIAC and the load when darkness falls.

The heart of the device is a light-sensitive cadmium-sulphide resistor, PR, with a resistance of approximately 200 kΩ in the dark and decreasing to a few kilohms in the light. PR and capacitor C1 form an ac-voltage divider. In daylight, the voltage across PR is too low to generate the required gate-trigger current to turn on bidirectional ac switch Q1, thus keeping the load – usually a lamp – off. When it becomes dark, PR’s resistance rises, resulting in an increase in the TRIAC’s gate current that triggers the TRIAC and lights the lamp.

The circuit uses inexpensive, off-the-shelf components, including the VT90N1 photoresistor; a 0.1-μF, 275V capacitor; and an L2004F61 TRIAC with a load current of 4A rms, a peak blocking voltage of 200V, and a gate-trigger current of 5 mA. The exact specifications of these components are not critical; you could use others instead.

Editor’s note:
Attributes worth mentioning include the fact that the capacitor introduces a phase shift, which places the peak of the gate voltage close to the zero crossing of the load’s sine wave for optimum turn-on timing. Another benefit is thermal hysteresis, which occurs due to the reduction of the required triggering voltage and current as the TRIAC warms up after the initial turn-on. Link
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