I made a small dynamo and failed

I'm trying to make a small, magnetic induction generator and I keep failing. I'm a noob at this and would highly appreciate some help.

My first attempt was a simple tube with copper wire around it, and a magnet that I tried to spin inside the tube to generate electricity.

First tube attempt:

Magnets I was using:

The copper wire is 0.3mm thick and the magnets are neodymium. The cylinder magnets' polarity is at the top and bottom. The rectangle magnets' polarity is on the sides.

After my first attempt, I noticed I'm generating some energy by pushing the magnet in and out of the tube, but not when the magnet is spinning inside. I then read a bit and thought my problem was that the copper wire was wound horizontally instead of vertically. So I made this second tube:



And it still looks like it generates a little bit of energy when the magnet goes in and out instead of spinning. It's such a small voltage I have to go to the 200m portion of the voltage-meter to see anything.
I can spin the magnet very fast (with an electric drill) and I only get like 00.2 or 00.3, but when I try to push it in and out I get bursts of 00.8 - 2.00. (I don't even know if that's in Volts).
That's with the rectangle magnet, the cylinder magnet only generates a bit of electricity when pushed in and out, and nothing when it spins.

Can anyone please help me? What am I doing wrong? How can I build this so it will generate as much energy as possible with the magnet spinning inside?

Thanks a lot for your time


What am I doing wrong? I just want to be able to power a small LED or something.

looks like your fields are sideways. those cylinder neo magnets the poles are usually top and bottom. Generators rely on the poles going in and out of the coil then when the magnet comes back around the voltage reverses so you will have to add some diodes so you get voltage in one direction... Here is what you made...

David Baillie wrote:looks like your fields are sideways. those cylinder neo magnets the poles are usually top and bottom. Generators rely on the poles going in and out of the coil then when the magnet comes back around the voltage reverses so you will have to add some diodes so you get voltage in one direction... Here is what you made...

Thanks a lot for the comment! I also tried with the rectangle magnet which has its poles on the sides, should that work for spin instead of up and down?

A fine experiment! Hope it works out. What source of mechanical energy would you ultimately like to harness?

A side note: a discarded cordless drill has a DC motor (generator) and a gear-and-bearing system all pre-built for you. Just add torque  ... ;-)

It sounds like the meter is indicating 2 millivolts at best.

The wall of the tube looks quite thick. Losing a lot of potential there. Most commercial generators & motors have a very thin gap of AIR between the magnets & the coils. Is the magnet strong enough to hold a piece of iron securely in place through the tube? The stronger the magnet & the more wire wraps the better. I suggest trying a thinner wire with more wraps per given volume & stronger magnets & a faster spin speed & possibly even more coils of wire. You're on the right track. The devil is in the details.

It looks like the wire is wrapped around pieces of a plastic frame. You might want to research iron core transformers a bit. The short explanation is that using iron cores (isolated from each other & the main tube) will increase the desired effect.

Lenz's law might also provide some useful insight.

Once you get a usable amount of voltage I'd use a simple Wheatstone bridge rectifier rather than a single diode for the DC conversion.

Good luck with your project & welcome to permies.

Douglas Alpenstock - Thanks! I can't disclose that right now but I definitely will once I know a bit more.

That's a great idea, maybe it's best to just get a dynamo or motor and try to connect my mechanical energy source to that, and continue from there...

Mike Barkley - the wall of the tube is 1mm thick, the whole thing is 3d printed so it's not that easy to get a metal core. Yes, I can just barely hold a drill bit in the air with the copper coil when the magnet's inside. But I think that's with the cylinder magnets, not the square one.

What's "single diode"? I just wrapped the endings of the copper wire to the voltage-meter cables. Didn't add anything else.