LaBam

I have to build a dynamo for an engineering class. I thought maybe some of you guys might know how to build one. It will be powered by a .30 four-stroke. Thanks for your help!

vicman

My Feedback: (10)

Isn't it basically an electric motor in reverse?

LaBam

I have no idea, I usually don't mess with electric motors.(bad experience) I'll give it a try for trying's sake though. Thanks for your help.

vicman

My Feedback: (10)

Here, I will try to be a little more helpful this time.

http://www.phy6.org/earthmag/dynamos.htm

Very basic info but you can get the idea. If you take a regular electric motor and drive it with an engine it should create some amount of current. You may be able to demonstrate it with a small light bulb or a meter.

LaBam

Thanks, I see how it works now. Thank you. I was told I had to make a dynamo and I was like "um...dynamo?[sm=what_smile.gif] That seems really hard." The instructor just said get creative. Thank you so much.

pilotpete2

Sorta, but not all motors will act as a generator or dynamo, the best example is the ac induction motor since it does not have a magnetic field when no current is applied, hence no usable output when you spin it, even an auto generator or alternator will not produce any output without first energizing the field coils with current from the battery.
Our hobby motors will act as generators since they have a permanent magnet field or rotor (inrunner/outrunner) brushed motors will output noisy DC and the brushless motors will output AC, though ironically they are not usable as normal AC motors (they will not self start on fixed freq AC)
Pete

vicman

My Feedback: (10)

You can couple your .30 to a 400 can motor and do what you need to I would think. Simple and creative.

LaBam

Yup, I've been working on it all day now. I took a battery powered circular saw and opened it up, snatched the motor, and mounted it to a board. Took the gear attatched to the circular saw and put it on my engine. And I'm about to run to the hobby shop to pick up a belt. I will post some pictures later to show you guys how it turned out. Thanks again for all your help!

vicman

My Feedback: (10)

A few heavy O-Rings would work fine.

LaBam

Well, forget my last idea. I went to the hobby shop and they gave me a motor and some gears. It fits perfectly and there is enough room for me to use a starter. It was really cool of them to just give it to me, I didn't pay a penny!

vicman

My Feedback: (10)

The reason is they want you spend your next hobby $ with them and not somone online. Please remember that and support them.

FMB42

There are many different types of "dynos" with electric, water, fan, and friction being the most common. Water dynos are very popular due to low cost and high load ability. Google should have many sites that cover the different types of Dynos. Good luck with your project and class!