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David Herres

David Herres holds a New Hampshire Master Electrician’s license and has worked as an electrician in the northern part of that state for many years. He has focused on writing since 2006, having written for such magazines as ELEVATOR WORLD, Electrical Construction and Maintenance, Cabling Business, Electrical Business, Nuts and Volts, PV Magazine, Electrical Connection, Solar Connection, Solar Industry Magazine, Fine Homebuilding Magazine and Engineering News.

Printed Circuits: Reliability for All

Printed Circuits: Reliability for All

By David Herres | August 1, 2021
Posted in |

Still, faulty operation in elevators must always be recognized as a possibility Value: 1 contact hour (0.1 CEU) This article is approved for Continuing Education by NAEC for CET® and CAT®. EW Continuing Education is currently approved in the following states: AL, AR, FL, GA, IL, IN, KY, MD, MO, MS, MT, OK, PA, VA,…

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Motor-Controllers-Figure-3

Motor Controllers

By David Herres | August 1, 2015
Posted in |

Types, requirements, and diagnostics and repair are among the aspects of motor controllers this overview addresses. The National Electrical Code (NEC), which has jurisdiction over subjects in which it has been enacted into law, specifies that any electric motor must have a controller. A motor controller may perform a multitude of functions. A principle purpose…

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Integrated-Circuits

Integrated Circuits

By David Herres | March 1, 2015
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The history, application and maintenance of these important microelectronics components are explored. In the microelectronics continuum, integrated circuits (ICs) are probably close to their midpoint of development. They have progressed far since their inception around the middle of the last century, but for the “smaller is better” theory, there is no endpoint in sight. To…

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hat-Is-a-Transistor

hat Is a Transistor?

By David Herres | December 1, 2014
Posted in |

Another major electronic component used in elevators is detailed. Like diodes, transistors are major players in the electronics arena, notably in elevator motion controllers and variable-frequency drives (VFDs) that have an extensive operator’s interface. Also like diodes, the transistor semiconductor mechanism is very simple in that it involves the attraction and repulsion of charge carriers…

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MOSFETs

MOSFETs

By David Herres | October 1, 2014
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This article on metal-oxide semiconductor field-effect transistors (MOSFETs) builds on lessons from the prior piece “What Is a Diode?” (ELEVATOR WORLD, August 2014). Metal-oxide semiconductor field-effect transistors (MOSFETs) are similar to the junction field-effect transistors (JFETs) that came before. In a MOSFET, the gate is insulated from the rest of the device by a layer…

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What-Is-a-Diode

What Is a Diode?

By David Herres | August 1, 2014
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The first diodes were the cat’s whiskers used to extract audio from a modulated radio frequency signal. Then there were diode vacuum tubes that performed the same function but were much more stable. Today, we are just about always talking about a silicon-based semiconductor device. These are very common in our electronic world and beyond,…

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VF-Drives

VF Drives

By David Herres | February 1, 2014
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Humans have made use of elevators for centuries, but real advances were not possible until the introduction of the electric motor. There had been water-hydraulic-powered elevators, and before them, human- and animal-powered machines. Even if we could ignore the humanitarian implications, it would be hard to imagine that these arrangements would work in the context…

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Electric-Motors-for-Elevators

Electric Motors for Elevators

By David Herres | February 1, 2013
Posted in | |

The first motors operated on DC. In fact, the invention of a practical DC motor long preceded Nikola Tesla’s insight that AC would offer substantial benefits. Thomas Edison and his associates clung to the idea that DC was more practical, but history favored Tesla and George Westinghouse, at least in regard to the war of…

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