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 Many notable people were born in July, but few have carried as much influence in the world industrial market as this Croatian born on July 10, 1856. He was a contemporary of Thomas Edison and worked closely with him. Eventually their relationship dissolved in a bitter feud between whether AC or DC was the most efficient means for carrying electrical signals. (For the record, Edison believed that DC power was preferred and invested considerable resources to defend that position.)
Among his many inventions were the the use of polyphase electrical induction for motors, generators and transformers eventually leading to the basis for AC induction motors in use today.
He was also very active in the field of radio transmission and wireless power transmission. He invented the tuned transmitter/receiver pair that is used in all radio transmission schemes today. Some of his ideas included the equivalent of high powered laser-type weapons - much like "Star Wars" and he was responsible for over 700 patents. If you want to read more about this clever and prolific inventor - just click the picture, above.
Though he's not a household name, he is well know amongst the engineering community and he does have a unit of magnetic flux density named after him: the Tesla. |
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Can You Solve This? |
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 Some of the problems we encounter are easy to solve, others require a little more thought. This month's challenge is in the latter category. We were working with an installation that required intrinsically safe encoders - which by necessity operate at lower voltages, typically less than 10 volts. The customer had wired up his encoder correctly to an Intrinsically Safe barrier required by the regulatory agency and all seemed to be operating well - at least for a while. Then they began to see intermittent shut downs of the encoder/barrier system. They could limp along by powering down, waiting a few minutes and powering back up again, but that is no way to run a production operation.
We reviewed the customers schematic and determined that their wiring was correct. After some discussions about the physical layout, the problems slowly became more evident. What was it about their physical layout that provided a clue to the problems that they were having?
Answer: Since they were operating in an intrinsically safe installation, they had fairly large distances between equipment to ensure separation between hazardous zones and safe zones. This required long cable runs. Conventional wisdom might cause one to think that excessive voltage drops were the issue, but the intermittent operation was a clue that the components were being driven too hard. A check of the cable specifications revealed that they were using a high capacitance cable which was causing a high load on the output drivers of their encoder and barrier. This condition resulted in activating the thermal shutdown protection. Switching to lower capacitance cable and closer attention to routing to minimize cable lengths was the answer. |
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Voices from the Past
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So often, the development of modern technologies allow us to look back into the past with fresh eyes. As an example, x-ray technologies have enabled us to uncover secrets in  Egyptian mummies and under old paintings without having to destroy these artifacts in the process. New digital scanning technologies have now enabled the recovery of a 150 year old voice recording by a French inventor.
The device on the right is a phonautograph which recorded sound on a piece of paper that had been blackened with soot. Edouard-Leon Scott de Martinville invented the device and in 1860 had a young female singer record "Au Clair de la Lune". Though the device was never intended for playback, a group of audio engineers and sound archivists were able to photograph and digitally "read" the sound.
To read more about this recording and to hear a 10-second snippet of this ethereal voice from another century, just click on the picture above. |
