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Author Topic: Dia. Mag. Alternator  (Read 190931 times)

z.monkey

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Re: Dia. Mag. Alternator
« Reply #150 on: December 09, 2010, 01:39:57 PM »
I've been trying to find low voltage bulbs that fit the Edison base.  The lowest voltage bulb that I could find local was 24 Volts.  It does light the bulb but not to full intensity.  I have some other 6.3 Volt bulbs but they are a bayonet base, and I would have to take the cool Edison base off my load jig...   Wah...

Video of the Light Bulb Test...
http://www.youtube.com/watch?v=O4iHdNWo86k

gyulasun

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Re: Dia. Mag. Alternator
« Reply #151 on: December 09, 2010, 08:25:01 PM »
Hi z.monkey,

What is the DC resistance of your present coils? Also, if you have an L meter at hand, would be good to know the coils average inductance (on average I mean its change when rotor is slowly rotated).
I ask these because knowing these data a good optimum load impedance could be estimated that could insure a power match Zgen=Zload to get the highest output at a given rpm. The 24V light bulb gave a light load at random but if you use a 6.3V bulb its brightness will still depend on its wattage rate.
I guess you surely know these.
Excellent job by the way!

Gyula

z.monkey

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Re: Dia. Mag. Alternator
« Reply #152 on: December 10, 2010, 12:57:36 PM »
Thanks Gyula,

Um, lets see, the coils are ~2.5 Ohms each, connected in series, out of phase 180 degrees.

I don't have an inductance meter, but I do have the magnet wire spec sheet...

http://www.belden.com/techdatas/english/8051.pdf

It give us the specific resistance of 22 AWG wire which is 16.2 Ohms per 1000 feet.

16.2 Ohms divided by 1000 feet is 0.0162 Ohms per foot...

5 Ohm coil divided by 0.0162 Ohms per foot is ~308 feet of wire divided by 2 coils = 154 feet per coil...

The data sheet also gives us linear turns per inch = 37.5, and turns per square inch = 1406...

The cross sectional area of the winding space is 0.5 inch x 0.75 inch = 0.375 square inches...

So, the number of windings we can fit in that space is ~ 527 windings per coil...

The core is Steel (Hard Iron) so its permeability is 8.75×10−4 uH/M (microHenries per Meter)

The core is an inch square, but the corners are rounded off, so I give the core area 0.95 Square Inches...

Convert that to metric and we have 2.413 Square Centimeters...

We plug all of this into an inductance equation...

Inductance = (permeability x number of turns squared x cross sectional area) divided by length...

Inductance = (0.00875 uH x 259091 turns2 x 2.413 cm2) / 1.27 cm = 4307 microHenries, 4.397 milliHenries, or 0.004397 Henries...

Of course my equation is not dynamic like a meter would be...

I may have to put that L-Meter on my Christmas list, good idea, thanks again...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #153 on: December 11, 2010, 01:56:14 AM »
Doh!

I even Forked Up the Equation...

"The core is Steel (Hard Iron) so its permeability is 8.75×10−4 uH/M (microHenries per Meter)"

s/b 8.75×10−4 uH/M, and...

"Inductance = (0.00875 uH x 259091 turns2 x 2.413 cm2) / 1.27 cm = 4307 microHenries"

s/b Inductance = (0.000875 uH x 5272 turns x 2.413 cm2) / 1.27 cm = 430.7 microHenries...

There are a lot of caveats, nuances and idiosyncrasies to this induction stuffz...

nievesoliveras

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Re: Dia. Mag. Alternator
« Reply #154 on: December 11, 2010, 02:03:11 AM »
That generator is giving you a hard time.

z.monkey

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Re: Dia. Mag. Alternator
« Reply #155 on: December 11, 2010, 05:36:08 PM »
This isn't hard.  This is aggravating.  Hard was cutting the steel core plates...

So, anyway I changed my Load Jig to hold four bayonet lamp mounts.  These are the low Voltage lamps that are compatible with my Low Voltage Coils.  With a single lamp in the jig the lamp gets very bright.  As I add more lamps I get a bigger Voltage drop and the intensity goes down.  It will light 4 lamps, although the intensity is about a quarter of a single lamp...

I am still turning this with my drill at 23 Hertz, so the next step is to make it turn faster.  Its only turning about a third of where it should be, and we can go so much faster.  I'm thinking I can use a motor with an overdrive gear set to get the RPMs up...

gyulasun

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Re: Dia. Mag. Alternator
« Reply #156 on: December 12, 2010, 12:29:48 AM »
Hi zmonkey,

The real inductance value for your coils in series can only be measured with your would-be L meter because there exists a mutual inductance between them too and you cannot easily calculate it, do not bother about it...
I think your coils in series may have any inductance from several hundred uH to some mH and with your low rpm giving low working frequency AC voltage the inductive impedance is pretty much less than the DC resistance in series.  So you may consider your output impedance is only very slightly higher than the DC resistances in series, i.e. 5 Ohm, this is what a load should be matched to, to get the highest output power possible.
rgds,  Gyula

z.monkey

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Re: Dia. Mag. Alternator
« Reply #157 on: December 12, 2010, 01:09:46 AM »
Gyula,

Yeah, that's right, and the load I can manage reflects that.  I can run one half watt bulb at full brightness, or two at half brightness.  The new load jig helped to verify this...

Jesus,

The C clamps were taking some of the flux.  When I removed them, and added the integrated screw clamps the open circuit Voltage went up by 0.2 Volts.  Little tweak here, a little kludge there, a little finesse somewhere else, and eventually we will have a sweet alternator.  Last test the open circuit Voltage was 7.81 Volts, and now its 8.05 Volts...

Edit:  You know what we need to kick the efficiency through the roof is to fill in the gap between the magnets, and the core bore.  That is a giant gap for a flux field.  Mega loss of efficiency there.  There is 1/16 of an inch there.  I thought about stuffing it with Iron filings, but they are a bit abrasive.  What about magnetic fluid, perhaps a lubricant, with microscopic iron spheres, like micro ball bearings... 

Hmmm,  yes, hmmm...
« Last Edit: December 12, 2010, 01:36:52 AM by z.monkey »

z.monkey

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Re: Dia. Mag. Alternator
« Reply #158 on: December 12, 2010, 02:37:20 AM »
And now for a note about another set of physics...

Mechanical tension...  A source of friction, and inefficiency...

My gears were gnashing, oh noes...

So I adjusted the mounting points and freed up the gears, and it netted another 0.52 Volts...

Was just at 8.05 Volts open circuit, now at 8.57 Volts...

Awesomes...
« Last Edit: December 12, 2010, 01:39:13 PM by z.monkey »

z.monkey

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Re: Dia. Mag. Alternator
« Reply #159 on: December 12, 2010, 03:09:20 AM »

nievesoliveras

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Re: Dia. Mag. Alternator
« Reply #160 on: December 12, 2010, 11:24:42 PM »
The bulbs flicked a little but after the generator went into speed they lighted very well.

Keep your good work!

FatBird

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Re: Dia. Mag. Alternator
« Reply #161 on: December 12, 2010, 11:42:22 PM »
Great photos.  Thanks.

z.monkey

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Re: Dia. Mag. Alternator
« Reply #162 on: December 14, 2010, 01:58:58 PM »
Make it go faster...

I pulled this motor out of my Bicycle Wheel Alternator.  Its a Dayton part number 2M197...

http://www.grainger.com/Grainger/wwg/search.shtml?searchQuery=2M197&op=search&Ntt=2M197&N=0&sst=subset

1/35 HP, 2350 RPMs on the label, but the spec sheet says you can push it to 3600...

Right where I want to be...

nievesoliveras

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Re: Dia. Mag. Alternator
« Reply #163 on: December 14, 2010, 02:11:27 PM »
The link you posted says that that motor has been discontinued. So in that case if it work well it will be unique.

z.monkey

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Re: Dia. Mag. Alternator
« Reply #164 on: December 15, 2010, 12:15:40 PM »
You know what we need to kick the efficiency through the roof is to fill in the gap between the magnets, and the core bore.  That is a giant gap for a flux field.  Mega loss of efficiency there.  There is 1/16 of an inch there.  I thought about stuffing it with Iron filings, but they are a bit abrasive.  What about magnetic fluid, perhaps a lubricant, with microscopic iron spheres, like micro ball bearings... 
Cheap, easy to make, yes its ferromagnetic fluid...

http://chemistry.about.com/od/demonstrationsexperiments/ss/liquidmagnet.htm

http://www.youtube.com/watch?v=vsQh1AT6qUE

http://www.youtube.com/watch?v=kL8R8SfuXp8&feature=channel

This is the game changer.  "The Gap" has been the bane of electromagnetic experimenters for a couple of centuries.  We shall fill the gap...

Just what I was talking about little ferrous particles suspended in an oil.  Yes!  Although I think I'll use motor oil.  I'll need to seal the bores now...
« Last Edit: December 15, 2010, 01:01:50 PM by z.monkey »