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Low RPM Generators

This is the main page on this site regarding the construction of generators. While many of the examples are regarding wind driven generators, the principles regarding the generators themselves apply equally to other motive sources. Anyone contemplating building a low rpm generator should look through all the sources on this page. Those persons specifically building a wind generator should also look at our "WIND" page which has on it many things specific to wind generators such as towers, blades, tails and testing them.

Comparison of Generators and Alternators

Most generators and alternators (like off of a car) need to revolve at around 1800 rpm (that is they have to make 1800 revolutions per minute in order to generate power) and it is often difficult to get a third of that speed with most homemade wind, water or other sources.

Overview: Comparison of Alternators and Generators

Low RPM Generators and Alternators

Since the difficulty with most generators is that you have to turn them too fast before they start generating power these low RPM ones are neat because they put out power at low rpm and so will work with a bicycle, a low head water source, or lower wind power.

The low RPM generators will start generating power at around 100 rpm and remain efficient up to about 600 rpm. Their "sweet spot" is often around 400 rpm but it will vary from generator to generator.

Brakedrum Generators and Alternators

Brakedrum: Use the brakedrum off an old pickup truck to make a low RPM generator!

Front Disk Generators and Alternators

There seems to be a trend away from brakedrums to disks. Talking with Hugh Piggot, he tells me that he is writing a new book on this subject.

Disk 1: Forcefield Low RPM Disk Alternator

Disk 2: Making a Volvo Front Brake Disk into a Generator

Wooden Generators and Alternators

Some wind generator designs can be put together very quickly. You can carve less elegant blade designs in an hour or two. Some motors can be used as generators. People have gone out and stuck their wind generators up on top of a hydro pole that is not being used. Hopefully the need is only temporary anyhow, until a more permanent source of electricty is re-established.

These may not produce so much electricity as a metal based generator and may be not as durable but they may be more accessible for one of the main components.

Simplest: Wood Axe

Wooden 2: all the plans and information for another wooden one

Wooden 3: A key set of plans to study

These are 49 mirrored pages of plans in .pdf format are ones that you can download and print off NOW. While you may not build this unit - you should definitely study these plans from Hugh Piggot because they give you details on many subjects such as how to build a coiler, the winding of a coil and how to wire the coils together.

On-line Info: Lots of info on build it yourself windmills

On-line Info: North American Source for Hugh's info.

Other Generators and Alternators

Microwave Oven: Making a Microwave Oven into a Generator


Experiment: Testing your theories

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