The main objective of this project is teaching everyone the basic principles of dynamos, this way everyone will be able to build a generator that can be used to convert different kind of motions into energy. This time I’ll show the steps on how to build a simple and cheap wave energy converter (WEC).
Step 1: What You Need to Know
Based on the Faraday's law of induction we know that E=-N*dB/dt which "translated" into normal English says, the electromotive force is equal to the number of turns (of the wire) multiplied to the change of the magnetic field within time. So let’s imagine we have a long copper wire and we start spinning it so it looks like a compressed spring, and now let’s put a magnet that fits inside and start pulling it in and out. If we check the two ends of the wire with a multimeter we’ll see that it’s generating electrical current.
Step 2: Materials
For this prototype I used tubes of PVC :
- 2 of 2’’
- 2 of 5/8’’
- 2 of 3 /4’’
- 8 simple 90° elbow joints of 2''
- 8 simple T joints of 2''
- 8 plastic caster wheels
- Copper wire
- Neodymium magnets (Any magnet will work but it won’t generate as much)
Step 3: Cuts
This project aims to show the basics of wave power conversion si it won't generate that much current/voltage
For a first try the measures are this:
1) Cut the 2” tube into 7.4” segments be sure to leave a bit more so you can polish the edges for an easy assemble. You’ll need 16 segments.
2) Cut the 3/4” and the 5/8” into 9.5”segments (no need to polish this ones). You’ll need 8 of each.
3) Cut the 2” tube into 4 segments, each being 18”.
Step 4: Assembly
1) Use a candle to heat the 7.4” long tubes so they can fit into the T’s and elbows, just heat one side in each tube and make 2 squares with the T’s facing up
2) Join both squares using the 18” segments
3) Drill a hole in each elbow, and place the screws from the caster wheels, be sure to cut out the secure so it won’t bother the rotation.
4) In each of the 3/4” tubes make a small cut 1inch from an edge and heat it so you get a plain part which you will also drill for it to fit inside the wheels.
5) Place the wheels with the tubes on the screws you placed in the elbows
Step 5: The Generator
On the 3/4 tubes you will start spinning the wire, now the estimation for each try is the next:
(Please nothe that I used 7 neodymium magnets of 14*5mm in only one tube)
- For around 100 spins the AC value is about 120uA
- For around 200 spins the AC value is about 21mA
- For around 800 spins the AC value is about 0.2A
Now it's up to you to decide how many spins you will make into each of the 3/4" tubes be sure to connect the coils in series.
Step 6: The Buoy
For the buoy I used an 8” diameter expanded polystyrene ball which was “secured using wire to keep it firmly joined to the 5/8” tubes.
It hasn't still been tested in the sea, but to use it safely in there, use some electrical tape to isolate the coils. Then you can put some silicone to prevent it from losing its stickiness.