Homemade Induction Generator


[Tyler LaVite] tipped us off about the generator he built. He combined a 5.5 horsepower Honda motor with a 10 horsepower electric bandsaw motor. To get an induction generator to produce alternating current you must feed electricity into the system to start the magnetic flux. [Tyler’s] solution was to include a bank of capacitors totaling 230mF which charge from the motor, then release back into the system. It’s not as green as the syngas generators we’ve seen since it still uses fossil fuel, but it reuses old parts sending less to the landfill.

33 thoughts on “Homemade Induction Generator

  1. Cool hack…but I’m with diago on the terminology oopsie: a lot of folks don’t seem to realize that a “motor” runs off electricity, and an “engine” runs off combustion. ;p

    Obviously the bandsaw motor is being used in reverse to generate the electricity…

    I’m wondering if an alternator would be sufficient for this as well? Alternators typically have to run at a constant speed which makes them useless for wind powered generators (which is what I’m working with atm,) but since you’ve got the lawnmower engine I wonder if it has sufficient RPMs?

    Anyhow, cool stuff — this got a few ideas going in my head for my own projects.


    1. Sorry to chime in years later. Just a bit of clarification for future readers. Your prime mover is the engine. It is used to move motors.

      Take an Hydraulic system for example. Whether I use a tractor PTO or a portable, Honda gasoline engine to turn a hydraulic pump, the primary mover is my engine. So, the tractor is my engine, the pump is a pump, and all the hydraulic motors I turn with the pumped fluid are motors. The same if I used Tyler’s Honda machine as the engine rather than the tractor to power my hydraulic system. His Honda would be the engine.

      Fire department guys tend to always think of their truck as an engine, because it the prime mover for multiple systems, including pneumatic, hydraulic, and water pumping systems. So, they will sometimes incorrectly look at Tyler’s Honda and say, “That isn’t an engine, that’s a motor.” But they are wrong about that. Tyler’s Honda in his electricity producing setup is indeed the engine.

      It can get more complex. Personally, while I may refer to Tyler’s JET electrical bandsaw mover as a motor, in this setup it is correctly identified as either a generator. That way you won’t get confused as you add electric motors downstream which move other devices.

      Last example. Say I use a Ford truck with a PTO as my primary mover. That becomes my engine. I attach an electricity generator to the PTO. That is my generator. I use the electricity generated to turn an electric machine which drives two belt driven water pumps. That electrical machine is a motor. I also use electricity to turn a second electrical machine which turns an air compressor pump. That second electrical machine is also a motor. With my remaining electricity I turn yet another electrical machine which turns an hydraulic pump. That third electrical machine is also a motor.

      In the cases of the air compressor and the hydraulic pump driven by your electrical system, that opens up even more to think about. Now you can set up your pneumatic and hydraulic systems. Remember how the conversation with your firefighter can get confusing because in his or her profession, the truck is always the engine? Now, when you are talking to a hydraulics guy or a pneumatics guy or gal they are going to want to think of your electric motor that drives the air or hydraulic pump as the primary mover in the system in which they specialize. They will want to call it the engine. Haha. Fun!

      But it all starts to make sense once you start to think about primary mover = engine.

  2. If that is a 10 HP bandsaw motor I am the King of France. it is probably a 1.0 HP. Secondly it is an A/C motor so it is irrelevant what direction it is spinning.Third this isn’t even a new attempt at a hack I built a generator in high school proably before this guy was even born.

  3. These generators arent expensive anyways, you can buy one under 300$. It’s the fuel what’s a bitch.

    You should figure out some battery charger for it as well to store the energy for later use. You could always put some cheap upses on it to normalize the AC current.

  4. @supershwa: actually I think “motor” can be used for anything that imparts motion. example: rocket motors. (probably came from the latin movere, which means to move)

    @Frits, I’ll let you think about that one for a minute. Solar panels convert sunlight (not heat) into electricity… ;)

  5. I like the apparent (it sure looks like) lack of a gas tank cap. :-)

    And what are those ‘PC fans’ blowing on in between the ‘motor’ and the ‘motor’?

    And I agree with Hacksaw – the motor looks to be about the size of, if not smaller than, my 1HP pool pump motor.

    Looks fun – great for a science fair project or something.

  6. @Hacksaw and @Joe,
    Inre: the apparent size of the electric motor.

    What if…
    it came off of a Craftsman bandsaw, then it might be a 10 (Craftsman) HP motor B^)

    For those that still don’t get it…
    Sears had a habit a few years back of exaggerating their HP ratings by using a “peak” number that was maybe possible on the back of an envelope, but not something the motor/engine could continuously provide.

  7. Hey I built this generator. The two fans are 115v cooling fans I added to blow air across the motor incase it got warm basically added for the hell of it. The motor is a JET brand motor for a large JET bandsaw it says 10 amps not 10 HP

  8. If this is going to be used as a generator and not just a science project, I hope a better exhaust is added to that engine. That thing will drive you nuts if you don’t.

    The PC fans seem to be blowing the engine heat away from the electric motor.

    Calling an electric motor a motor and a heat engine an engine has been common practice for a while now. I don’t think it’s an actual standard, but it helps avoid having to add prefixes to differentiate the two.

  9. Heh, I did something similar a while back. I had a motor connected to a stationary bike. I discovered that if I pedaled faster than the motor was spinning the bike, the lights on the same circuit visibly brightened.

  10. @ChalkBored

    >Calling an electric motor a motor and a heat
    >engine an engine has been common practice for a
    >while now. I don’t think it’s an actual
    >standard, but it helps avoid having to add
    >prefixes to differentiate the two.

    And calling a database of websites with a HTML public query interface a search “engine” ….

  11. @xrazorwirex: I guess not as you need ~200uF of total capacitance. Apparently it is possible to use cheap regular polarized electrolytics ‘back-to-back’, though they need to be double the size and rated at least the peak voltage.

    Google for ns8o’s induction generator page for a more thorough analysis and build instructions.

  12. So it is a 1.5 HP motor then. I used to have a Craftsman (Ryobi) table saw that claimed 5 hp (peak) SO I am familiar with their brand of lying. Jet BTW is just another imported tool (albeit imported by a very well respected company Powermatic) And the old stuff was actually quite good…when you could start buying them at the big box lumberyards(Menards in the midwest) that’s when the quality went to hell.

  13. For poos sake everyone calls them internal combustion ENGINES and servo MOTORS, its gas vs electric its been the unofficial standard since I was born. I don’t care about rocket ______ or search ______, file them as you will if it runs on gas its an engine if it runs on electricity its a motor. Now get with the program and start using clear easily understandable language that doesn’t make you sound to ignorant to be writing in the tech field, the rest of us get it why cant you?

    (This is far from the first HAD article with this specific confusion causing mess up, knock it off already, it makes me think less of the HAD writers and I’m sure I’m not alone in this sentiment)

  14. [It’s not as green as the syngas generators we’ve seen since it still uses fossil fuel, but it reuses old parts sending less to the landfill.]

    why do you ‘greenies’ incessantly bitch about filling a landfill?
    Think back to the water filter commercial — a minute on the excercise bike, forever in a landfill — referring to the bottle.

    Someone is MAKING MONEY on this eco-socialism agenda, and it isn’t me.

  15. Using old induction motors/alternators/etc to generate electricity is rather inefficient. I found a write up where some british guys wound their own permanent magnet generators using just magnets, wire, some hardware, and volvo brake rotors to hold everything. I think they even used some hub bearings from the volvo to rotate the pieces on. They were getting an incredible amount of power output from these things, it was pretty neat. THAT was an awesome project, and one that I intend to duplicate someday :D

  16. What Jake describes sound like engine powered version of an axial flux alternator. Often used on homemade wind turbines. Thing is they produce wild AC, and need to be rectified to DC and inverted back to AC to be practical. With no frequency control the power plant in this HaD post is not that practical.

    Oil field where all the well are powered from the same transformer have been know to keep pumping when the grid fails. Until one well goes down and muck up the balance anyway

  17. @D_

    You are absolutely correct, they were rectifying it and storing the energy in gel cells. That’s a good point, seeing that this hack does not require inverter circuitry and should be able to generate stable AC with proper speed control circuitry.

    I now have TWO Xantrex 5,000 watt inverters that I have scavenged, I would like to use those, along with some batteries and a generator much like the one in this article to give me a home-UPS such that my power never gets interrupted. Our power company used to be called “O&A”, we called them “O&O” for “Off and On”. We live in the middle of nowhere and lose power all the time!

  18. That engine sounds like it’s either running really rich, has a bad case of rod knock, or the governor is pulling WOT at 1200 rpm. Either adjust the carburetor, or if it needs wide open throttle to hold that RPM because of load, change the drive ratio with different pulleys. If it’s knocking, it won’t last much longer anyway. That engine is supposed to sound more like this:

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