856Views4Replies

# Copper and magnet electricity generator Answered

For a project in school we are designing a simple electric generator using copper wire and a magnet. The output i'm aiming for is 15V .The fixed criteria for Faraday's law as follows

E =( NBA ) / T

T= 3 seconds

B = Neodymium 1.32 T

so how do i chose my copper wire? what diameter? what kind? how do i keep the design not so BIG . How do i increase my voltage output by using a double coil system?

Tags:

## Discussions

The forums are retiring in 2021 and are now closed for new topics and comments.

Well, the place where your coil goes has some area, A. You already said that.

Realistically, this coil also has some thickness, d, and thus volume, V=A*d.

We can imagine filling this coil shaped space, V=A*d, in different ways. For example, this space can be filled with a huge number of turns of very tiny gauge wire. Or it can be small number of turns of fat gauge wire.

Those are basically the two extremes, regarding ways to wind your coil.

The problem of what size wire to use, is mostly determined by how low you want the total electrical resistance of the coil to be, and that number ultimately determines how much electrical power, I*V, the coil can deliver.

Because the thing you are contemplating is a school project, the actual useful power output can be low.

In fact power output can be as low as zero, in the case where your generator delivers just voltage, with zero current.

So, I think you want to build your coil with as fine gauge wire as possible, that way you can put more turns on it, since, as you have already pointed out, the coil voltage will be directly proportional to the number of turns.

Another way to increase voltage is to make your magnet sweep over the coil faster; i.e. make T smaller. However, this thing has to be demonstrated in a classroom, so a magnet moving like a speeding bullet, might be too dangerous. Or from a practical standpoint, how do you build a machine that can move its parts at high relative speeds, without shaking itself apart?

But would it not just be easier to put more turns on your coil? Rather than figure out how to make the magnet move at ridiculous speed? I mean I think will be easier to wind 10, or 100, times as many turns, compared to making the magnet move 10, or 100, times faster.

I have another suggestion too, and that is to find a pre-wound coil. Also I have some suggestions for places to look to find this pre-wound coil.

If you can find one of those dancing-solar-flower toys, those are built around a small, pancake-shaped coil, with many turns of very fine wire.

Also the stator, from the tick-tock, 2-step stepper motor found in a 1-cell, quartz timed, mechanical clock, has many turns of very fine wire.

I think I have some pictures of these my image library, and I will link to these pictures here:
https://www.instructables.com/ORIG/FUF/8DKW/IVO3MM...

https://www.instructables.com/ORIG/FY3/TM53/H5405O...

https://www.instructables.com/ORIG/FMV/WQP4/IVO3MM...

https://www.instructables.com/ORIG/F7J/SCI3/IVO3OT...

Dear Sir,
Im doing the same project as mentioned above, while I only managed to get about +-0.30 V AC. I am using 0.75mm thick of the copper wires with a numbers of turns. So for my situation, if I would like to increase the voltage, should I use a thinner copper wire instead in order to increase the voltage ?

Yes. You want a lot more turns, and the way to do that is by using thinner wire. If you can increase your number of turns by a factor of 10 or 20 then that should increase your peak voltage by the same amount; i.e from 0.3 to 10*0.3=3.0 volts, or 20*0.3=6.0 volts.

I am guessing that if you can decrease the wire thickness by a factor of about 4 or 5, the total number of turns that can fit in the same volume will increase by the square of that, by about 16 to 25.

In terms of wire gauge,

https://en.wikipedia.org/wiki/American_wire_gauge

I think that is the difference between 20 AWG (d=0.812 mm) and 32 AWG (d=0.202 mm) or 34 AWG (d=0.160 mm).

I don't know if you have seen 34 AWG wire, but it is really thin stuff. Actually it is in the same thickness range as human hair (0.02 to 0.20 mm) (or 20 to 200 um) if I can believe the intro paragraph from this page,

https://en.wikipedia.org/wiki/Micrometre

Speaking of seeing things, I recently fixed the links in the comment I wrote above. So those links should be pointing to some pictures of a homemade generator toy, with a pre-made, pancake shaped coil, of really thin copper wire.