Electronics and generators

In the last two decades alternators have replaced generators in motor vehicles. The reasons are many: output current can be produced at lower rpm, voltage can be more accurately' controlled with solid state regulators, alternators need less maintenance, and they cost less to manufacture.

When modified, auto alternators can provide variable direct current at 0 to 120 volts for battery charging, hot charging, light arc welding, or for running AC-DC appliances and lights. Another simple modification provides AC power to run some transformer-operated appliances. If you know the secrets of its operation and the modifications possible, the small low-cost alternator can become a versatile power plant.

Surprisingly, alternators are constructed with three sets of field windings positioned evenly at 120 degree intervals inside the frame. Such construction produces three-phase AC.

As many small-scale methods of electricity generation are available only intermittently, some form of electricity storage or battery is needed if people want to have electricity available at all times.

There are a wide range of batteries available, and the aim of this Technical Brief is to give an introduction to the advantages and disadvantages of the different types of batteries. The central point is that there is no such thing as a universal battery; a single type of battery cannot cover all applications.

This 21 page ebook starts with electric motor problems and current protection. Then the author moves on to the more advanced topics of electric motor variable speed drives operation and the effects of process changes on electric motors. Mixed with in the above sections, plant layout and vibration detection are discussed. There is also sections on the basics related to motor drive systems such as V belts, chains, bearings, grease and lubrication. All in basic technical briefs type format.

This manual describes how to build a 'permanent magnet generator' (PMG). We can also call it an 'alternator', because it generates alternating current (AC). It will not generate 'mains voltage' or 'utility power' AC. It generates low voltage, 'three phase' AC, and then changes it into 'direct current' (DC) for charging a 12 volt battery.

Energy Saving Trust on Ground Source Heat Pumps

This donlaod contains three files that will help you estimator your power requirements for your house, boat or caravan. There are two Wxcel spreadsheets and one pdf file. To get the most form this you need Excel howver you can use the information to make manual calculations.

Included are the power requirements for typicall applainces. The power estimator could be used to calculate your solar, wind, or another generator requirements. The documents are in the public domain.

About the author

David MacKay is a Professor in the Department of Physics at the University of Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD in Computation and Neural Systems at the California Institute of Technology. He returned to Cambridge as a Royal Society research fellow at Darwin College. He is internationally known for his research in machine learning, information theory, and communication systems, including the invention of Dasher, a software interface that enables efficient communication in any language with any muscle. He has taught Physics in Cambridge since 1995. Since 2005, he has devoted much of his time to public teaching about energy. He is a member of the World Economic Forum Global Agenda Council on Climate Change. He was elected a Fellow of the Royal Society on 14 May 2009.

About the "free book" license

This is a free book. I didn't write this book to make money. I wrote it because sustainable energy is important. If you would like to have the book for free for your own use, please help yourself to any of the electronic versions on this website. There's pdf and html versions (thanks to William Sigmund!); we are working on other formats.

This is a free book in a second sense: you are free to use all the material in this book, except for the cartoons and the photos with a named photographer, under the Creative Commons Attribution-Non-Commercial-Share-Alike 2.0 UK: England & Wales Licence. (The cartoons and photos are excepted because the authors have generally given me permission only to include their work, not to share it under a Creative Commons license.) You are especially welcome to use my materials for educational purposes. This website includes links to separate high-quality files for each of the figures in the book.

In response to generous readers...
If you enjoy the free electronic copy of the book and would like to make a financial donation, without buying the paper book for yourself, please may I suggest that you find a library or a school that would like a copy of the book, and buy a paper copy for them? Thank you!