Firstly, before I get to the details in describing the minigen and what it does I simply need to say this has been one of the most entertaining and versatile little generators I've ever had the opportunity to play around with. I'm quite confident you will equally share the many many hours of fun this thing can provide.
So, what is it and what does it do... Basically it is a single-phase high voltage surplus motor. Note that I did say high voltage and if you hold the wires and give it a spin it will definitely give you a little "bite". It is low power, however, so the bite isn't dangerous as it only produces about 0.025 amps ( 25ma ) but it does it at voltages that will exceed 150+. I certainly wouldn't want to test the output with my tongue !!! Ouch !!
Let's take a look at the inside for a view of how it works...
The picture doesn't give it any justice. If you look closely you'll see the steel finger cage, we'll call it a "monkey cage" for lack of a better term, the monkey cage is surrounded by 26 small magnets. There is a single coil between the two plates that make up the monkey cage. It comes apart in only a few minutes and is extremely easy to rewind for higher amps and lower voltage. I'll talk about this later. The monkey cage stays stationary and the magnets and hub spin around the outside. Quite perfect for lots of wind experiments and the 3 built in mounts make it very easy to mount just about anything to it. When you get tired of playing in the wind you could use it on your Hydro experiments, switch back and forth between the hamster and aardvark to power your lights...
The minigen is a bit bigger than the pictures might suggest, its 5.5 inches in diameter including the wing mounts, the thickness at around 2.5 inches and stands about 6.5 inches tall including the mounting tube. Weighs in at around 11 ounces depending on which model you purchased.
You'll notice when you spin it there is a bit of cogging, one way is less than the opposite direction and you'll want to design you turbine ( or what ever your project ) to spin in the direction of the least resistance. It works great in either direction.
Connect an LED to the output wires and you almost can't turn it slow enough to NOT light it. The output is AC ( alternating current ) and you'll need a rectifier to get it to light on every pulse ( ore cog). Below is a video showing a group of 12 Ultrabright White LED's connected to the minigen turning it very slowly... its about 177k ...
Another video below showing the voltage when turning it slowly... it's a little longer and is about 493k...
The little minigen will charge ni-cads and NiMH as well as slow charge 12v batteries, although, it's not a real powerhouse.
The minigen comes with a set of 3 blades making up a diameter of 34 inches so you can start playing with it the same day you get it ( wind not included ). Below are some pictures of the minigen turbine put together in less than a day...
Oh, and it even has a tilt up furling system !!! pretty cool for a quickie wind turbine !!!
Here is a closer shot of it's simple construction...
Start building in the morning and be flying in the afternoon wind !!!
Your only limited by your imagination with these. Here are some shots of a couple miniLenz turbines mounted on the minigen...
The shot on the right, difficult to see, is running in a 7mph wind making an open voltage of over 60 volts. You can save the picture to your files and re open it for a full size view.
Can you think of other ways to use the minigen? Maybe mount it to a small stirling engine? steam engine?
The above right miniLenz turbine was mounted in my homebuilt wind tunnel. Below shows the mini Lenz turbine mounted to the minigen running 2 strips of 11 Ultrabright red LED's ( 22 total )... in the same 7mph wind in the dark...
The minigen is a fantastic building block for those ingenious younger folk doing science projects or even some of us "older kids" that love to tinker. The sky is the limit !!!
The shaft of the minigen slips right into the small garden towers. Great for lighting the driveway, walkway or the frog pond...
If you want to change or alter its performance, rewinding the minigen is very simple. You remove the "C" clip from inside the slot and the magnet/mounting hub slides right off exposing the monkey cage in all its glory. The picture below shows the slot exposing the "C" clip...
Once the magnet ring is off, simply unscrew the bolt and the monkey cage will come apart and you'll have the coil in your hands. Remove the old wire and rewind it with larger wire. I mounted the spool on a drill and rewound one with #32 wire. The more wire you put on the spool the higher the voltage, the larger the wire you use will increase amps. Once the spool has been rewound simply solder the output wires and reassemble it. Your back up and running in no time. The next photo shows the bolt that you'll unscrew to remove the monkey cage and pull the coil...
Below shows the minigen apart and the coil rewound and ready to reassemble.
There are other ways to get around rewinding it for higher amp output and if you'd rather not rewind it here is a simple way. You can increase the amp output by simply using a common "wall wart". You know those pesky little AC/DC transformers that seem to come with everything you buy. They range from 3v-12v output and 120 volt input. You can connect the output leads from the minigen directly to the plug spikes and it will take the higher voltage AC and convert it to the lower voltage higher amp DC output. A couple that I tried boosted output from 25ma to 60ma and in the 6 volt range just over 200 ma. A quick and simple way to increase output and the rectifiers are built in. Also, if you have a small ni-cad/NiMH battery charger with a wall wart you can drive it directly from the minigen to charge the batteries. ( at your own risk of course ). I tried one of mine ( a cheapie ) and it worked great. Some that are more sophisticated may have some picky electronics. Look for the really cheap ones.
A 120VAC to 12vac transformers work very well also. I used one and boosted output to 400 ma at 3 volts. The transformer was a Radio Shack # 273-1352A with 120vac input and center tapped for either 6 or 12v output. You will need to rectify the output to convert it to DC for battery charging or running LED's. The photo above of the night shot was done using a wall wart in the 12 volt range.
Ok, now to the nitty gritty... what's it going to take to own one... Well you'll be pleased to know they aren't expensive at all !!! There are 2 models of this surplus motor, one has a plastic housing and the other has a metal housing as shown in the picture below...
The one on the left is the plastic housing and has a smaller diameter with smaller magnets and the output is as you may have guessed a bit lower than the other. The metal one is larger, higher output and a bit sturdier than the plastic model. They both come with the motor, 3 wings and mounting hardware and are priced as follows...
Plastic housing set ( left picture ) $24.95 Sold out sorry
Metal housing set ( right picture ) $29.95 Sold out sorry
I may be getting more - check back -
NOTE: I have a limited supply of these so get them while you can !
Shipping for one minigen in the US is $7.00
email me for shipping quotes to other places.
I can accept paypal payments to elenz(at)windstuffnow(dot)com
Sets come as shown below...
NOTE: I've noticed on the metal minigens some will cog more than others. You'll notice it cogs less in one direction than the other. Unfortunately, it typically turns in the direction it cogs the most. To cure this problem there are a few things you can try. You can remove the magnet cover and loosen the nut holding the cage together and try offsetting the fingers in one direction or the other. This will help to some extent. Another approach is to bend the fingers away from the magnets a little increasing the air gap. The cure is to remove the nut and flip the entire cage over. To do this you'll need to disassemble the unit and un-solder the wires going to the coil. Split the cage halves and remove the coil. Take the bottom cage section and place it on the top cage section and drill the two wire holes using a 3/16" drill. Reassemble the cage and re-install it on the post, solder the wire leads and the cogging issue is gone. Make sure you don't center the fingers on the cage, you want to offset them when you re-assemble it.