This is a tutorial to building your own portable mini electric generator. This generator converts the kinetic energy of turning an axle into electrical energy to power whatever circuit you want. This project will grow your 3D printing skills as well as build understanding in electronics and magnetism.
Step 1) 3D Printing:
The gcode for the parts you will need to print is posted below. There are 4 parts in total, the coil spools, magnet plate number 1, magnet plate number 2, and the Spool and circuit frame.
When printing make sure to use the prusa printer(the orange one) with PLA plastic. This gcode will not run correctly on the other printers. You may need to sand down particular pieces to make them fit together if they are too snug of a fit.
It will probably take around 4 hours in total printing time for all 4 pieces. If you are confused about the #D printing process consult the makerspace wiki or talk to Aaron.
Step 2) Magnet Wire and Spool Construction:
Take the two spool holders remove the support material from the printing process
Start coiling your magnet wire around the spool leave plenty of wire sticking out so it is easy to work with when you insert it into the generator frame. Remember you can always cut off extra wire at the end. If you want to get a tighter winding than you can do by hand, try using a hand drill and sticking the spool in as the drill bit.
Coil the wire like a spring around the spool, making it tight as possible. MAKE SURE THAT DIRECTION OF THE COILS IS CONSISTENT THROUGHOUT THE COIL. You want every loop in the spool to have the same orientation, only looping backward to start the next layer. A picture is included for reference, this is what each layer should look like to be the most efficient.
Fill up the spool completely.
Repeat this process for the other spool
Step 3) Spool insertion:
First cut off the extra handle attached to the spools. I found that this was easiest with the shears in the maker space, but you can also use saw or heavy duty scissors. Make sure to sand down the leftover nub so that it is flush with the top of the spool.
Insert the spools into the frame. Stick the two output wires through the small holes on the side. This way they wont interfere with the rotation of the generator and are easier to access.
The spools should fit in snuggly into the design. If they are too lose secure the spools in place, with glue or tape in a way that wont compromise the movement of the generator.
Step 4) Magnet Disc Assembly
Find 16 .25in neodymium magnets from the makerspace and some super glue. Be carful with the super glue, it instantly binds to skin so try not to touch it directly. Insert the magnets into the plates ALTERNATING THE ORENTAION EVERY TIME out put one in. This means that each of the magnets should be facing opposite of each of there neighbors. For example. If one of the magnets is facing north side up then the the two magnets next to it in the circle are facing south side up. This way each plate has 4 north side facing up and 4 south side facing up. This is very important and easy to mess up on. Once the magnets are inserted with the super glue they will be incredibly difficult to get out so it might be worth doing a practice run without the super glue.
Step 5) Final Assembly:
Insert the main frame with the completed spools into the magnet plate with the axle. Then insert the other magnet plate face down on top of the main frame.
NOTE: The orientation of the two magnet plates is very important. You need the magnetic fields of each of the two plates to line up with each other so that if the frame wasn't there they snap to each other. This means that the top plates south side magnets will need to be directly above the bottoms plates north side magnets. This creates the maximum magnetic field in the coils. Make sure to take the time to do this step right.
Once you are sure the plates are connected in the right orientation you can hot glue the top plate to the axle so that it wont move at all, sandwiching all of the parts together. After this step the Generator should be fully functional. You can test it with an oscilloscope to see the waveform it produces. A makerspaces prototype board should strew in perfectly to the main frame of the generator if you want to build a portable circuit on it.
(Optional) Step 6) LED display:
Now you have a working generator! But if you want a visual representation of what the current is doing then here is a circuit that you can make and hook up to your generator. Here is what you will need:
3 1k ohm resistors
1 10k ohm resistor
breadboard and some wires
The circuit diagrams is shown in the image below. This circuit uses the op amp and a comparator which will send create a 30V ptp square wave when the generator running. This waveform is then outputted to a voltage divider which cuts the voltage in half before going to the LED. Build this on a breadboard and connect your generator to watch the light turn on whenever you spin the axle. This circuit can also be the foundation of many other electronic circuits you may want to use the generator for.