An FM Generator Circuit Using the Capacitance of a Collector-Base Junction

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The Mystery of USB Chargers

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By  Jestine Yong  on July 9, 2014 Almost any new device such as mobile phone, tablet, iPod, GPS etc… will come with some sort of USB Charger and a cable. The cable will connect to your device through a dedicated connector, mini USB, micro USB or manufacturer’s specific. At the other end, most cables will be terminated with the familiar USB connector (USB type A), which you can connect either to the charger or to your computer. If you are like the 50% of mobile phone users you will buy a second charger, just to have one at work and one at home. Over the years, you will end up with several USB chargers and you might wonder if you could simplify your life by having only one charger, or at least a couple of chargers, for all your devices. The problem is that they are not all compatible. Your Samsung charger will not work with your Apple device etc… In this article we will analyze some USB chargers and find out why they are so different. And may be find out that they are ...
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Programação de um CLP: Modos de programação

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No seguimento do curso de Automação, neste artigo apresento como perceber os conceitos básicos de programação de um CLP. No decorrer das próximas edições apresentaremos a forma de programar um controlador lógico programável Autores: Filipe Pereira - Eng. Elétrotécnico / Automação Klean Energie 4 Life, Ltda Energias Renováveis - Portugal As linguagens de programação são empregadas nos CLPs desde que estes surgiram em 1960. Estas permitem ao usuário inserir programas de controle utilizando sintaxes pré-estabelecidas. Previamente ao estudo dos três tipos de linguagem mais utilizados na programação de CLPs, convém rever alguns conceitos essenciais. O programa que vai definir o automatismo é constituído por uma série de instruções e funções onde são operados os bits de memória. Estas instruções e funções, serão introduzidas na memória do CLP, através de um periférico destinado a esse fim e que poderá ser uma console de programação ou software específico para PC. Veja na figura 1 u...
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STRONG SRT 4622 Satellite TV Receiver Repaired

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By   Jestine Yong   on November 21, 2013 2   The problem of this receiver was a bad picture. In order to make sure that the LNB DISH and Signal Cable are working fine, I installed another good receiver to the end of the line and I received a very beautiful and sharp picture and this indicated the LNB dish all the way down to receiver were working fine. This means the problem for sure is the receiver set. Note:  LNB stands for  low-noise block  and the function is to  receive the very low level microwave signal from the satellite, amplifies it, changes the signals to a lower frequency band and sends them down the cable to the indoor receiver unit. After opening the cover, the first thing I checked was the output voltages from power supply. More or less all of the output voltages readings were within tolerance:   5 v     was    5.17       3.3        ” ...
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