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Chuck, I would like to be following this along but I should have said earlier that my internet provider won't let me see your photos because it has decided to block acess to where ever you are hosting them. Jo
Chuck,do you intend the coils of the stator to be fake and have magnets inside? If not, a coil without (iron; better ferromagnetic) core is quite ineffective. For iron, µr is 300…10000, for ferrites, it is 4…15000. So that's the factor your field strength is reduced by not having a core.Nick
Hi Chuck If you don't mind me asking how did you arrive at the 60-70 turns? If I do the maths it equates to coil height of 5mm to 5.5mm - it looks a bit bigger than that, maybe1/4" which should give you about 95 turns (tight wound) N=0.707*H2/d2 N= Number of turnsd=diameter of wire #24 = 0.55mmH=Height of Coil(along the coil axis) Where H=5, N=60Where H=5.5 N=70Where H=6.35 N=95 of course there is a tidy factor. If I was winding them myself in a hurry you would have to half all those calculations Bez
I built a little alternator a few weeks ago, it was a little shaded pole motor, 850 rpm type. I took out the armature, and made a new one, it is a 6 finger claw (similar automotive alternator), with 3 ferrite magnets removed from old speakers inside, this will produce about 90V, and gives useful power when fed through a transformer, and a bridge rectifier, to give about 12V. This alternator was designed for the Stuart S9 .
Jo, I've been hosting my photos in a public folder of http://www.dropbox.com for some months now. These include the Fairbanks and the radial 3 compressed air. Are you not able to see pictures from any of my recent posts? Is anybody else having a problem seeing them?
Chuck, I wanted to remove the pole shading rings(they are just used for starting these motors), but I would have to remove the main windings, and I'm too lazy to do a rewind, although I could fit in heavier wire, which would be useful in increasing the current, it was a 150 watt motor. Ian S C
Hi Chuck I don't think you'll have much trouble making enough juice to drive a couple of Doz White LEDs at about 60mW each. I guess we'll get to see eventually but some of us are impatient mugs.. so I'll ask now What will you be using for your induction source? and how will they be configured? by that I mean; with the eight windings were you aiming to get 60Hz at 900rpm? There is just so many ways you could set this up. Oh! By the way... if these questions are gettig in the way of building this thing... just skip the answers & go streight to the workshop so you can get more progress photos. Bez
Not sure what you mean by induction source. The armature will have 16 bar magnets arranged with alternating N & S poles facing outward. The coils will all be hooked in series. This will allow all the south poles to pass the coils at once followed by all the north poles passing the coils at once.Chuck
Just wire your LEDs in pairs back to back with a series current limiter.
QuoteJust wire your LEDs in pairs back to back with a series current limiter. I think you mean to wire them anti-parallel. But LEDs will mostly fail at a reverse voltage above 5 V!Chuck, I hope the magnets are properly oriented, you can get them in (at least) two orientations.Nick
Hi Chuck, the magnets you are using and this is just a question. When you purchased the magnets, did they specify that the north and south poles were end to end or front to back? Don
We both know the reverse bias voltage on one diode of the pair can never exceed the forward bias voltage of the other.
I received my magnets from KJMagnetics and installed 8 of them on my armature. I've done a bit of testing and results are a bit disappointing, but I think I will be able to get it where I want it. I've installed 8 magnets and have 200 turns of #27 wire on one pole of the stator. Turning the armature at somewhere around 1500 RPM's and feeding the output through a full wave rectifier gives me .25 volts. Multiplied by 8 would give me 2 volts. That's probably enough to light an LED but if I add another 8 magnets, I'm thinking I'll get 4 volts and if I add 16 magnets I should get 6 volts. Since the #27 wire is rated at .287 amps, I'm guessing an incandescent lamp is out of the question.Chuck
I was able to light a large LED with the full wave DC, but when I took out the rectifier, it wouldn't light with straight AC. Chuck
If you look at a motor, and keep in mind that it is just the reverse of a generator, things get more obvious. The higher the voltage, the faster it turns. The more poles, the faster it turns.The higher the load, the more amps.Nick
Nick, I Think you are talking about a DC Motor, speed is a function of poles and Frequency of the source for AC motor.
So, the quandry is why 3.4 DC volts would light the bulb and 3.6 AC volts wouldn't. I realize with the AC voltage, that current would only flow for 1/2 of each cycle and the other half is essentially wasted, but I would have thought that would still be enough to light the bulb. Perhaps the amount of current being produced is so small, 1/2 a cycle just isn't enough.By the way, I'm assuming when I measure the AC at 3.6 volts, that means 3.6 volts positive wave followed by 3.6 volts negative wave. Don't know if that is peak voltage or RMS.Chuck
So, the quandry is why 3.4 DC volts would light the bulb and 3.6 AC volts wouldn't. I realize with the AC voltage, that current would only flow for 1/2 of each cycle and the other half is essentially wasted, but I would have thought that would still be enough to light the bulb. Perhaps the amount of current being produced is so small, 1/2 a cycle just isn't enough.Chuck
Chuck,You are definitely are the right track. Many poles, many turns, and a steel stator will give you a reasonably high voltage output at low RPM. How are you planning on managing the cogging effect that a steel stator and permanent magnets will create?Jeff
Chuck why are you using a steel stator? You should have no cogging because there are no steel pole pieces. The steel stator is only good if the pole pieces are steel to help distribute the magnetic lines of force. Sorry bud but this will not help much. The steel ring will increase eddy current losses.Your orginal design should product more output then you have. Did you pass a compass inside the stator to check that the poles were north and south on every other poles. Just use a battery to power the stator with to do this. Do it just to double check they are correct.Don
Thanks, Bez. Actually I started with 6 LED's, the went to 12, and finally 18, all that I had. I suspect it would have driven more. However, I'm also hoping to run the engine at about 600 or 700 RPM, not the 1500 that my cordless drill provided.