My little genny

[willib]

These are the coils on my little genny ..

 

there are 18 coils and 24 magnets as keeping with the coil to magnet ratio of 3/4 ..

the coils are wound with # 20 gage wire  and are 0.96" inches in dia ,  well most are anyways, some are 1.020''..

i had origionally wound them with #17 gage wire , but wasnt getting the voltage i wanted..

these are much better..

they give an open circuit rectified three phase voltage of 22V..

the short circuit current into an ammeter ,is 5.34A @ around 2V..

although i havnt got the room to install it outside , i do have it hooked to an excercise bicycle , and use it to charge NiMH batteries all the time..

the magnets 1/2"dia. x 1/2" cylinder neo magnets ..

[iFred]

it's a pretty design is'nt it. I build one much much bigger then this about 3 years ago. Here are my suggestions. Your not completing the magnetic path for your screws. You need to consider a bolt that connects to metal backing. This would increase your output 100 fold easly. Your amps and volts would go through the roof. The problem is cogging, but if your magnets to coils on your rotor which I assume is metal as well then you should'nt have any problems, though you will notice it anyway, however the power output will more then make up for it. (you can also stagger or sku the magnets) Good Luck.

[iFred]

[willib]

Fred, i was just browsing your photo list ( hope you dont mind).?

Is that a solar powered motor , with magnetic bearings, on each end ?? that is cool..howd it work out for ya?

The magnets are stuck to a 8" saw blade..

The screws in my generator are brass and stainless to avoid cogging.

Because of the thinness of the blade , vibration is a problem..because it bends..lol

That is an old 5.25" hard drive bearing in the center of the coil pic..

[willib]

Which would be better ?

i have some new magnets on order, 7/8" dia. x 1/2" long , supposedly 37 lb. pull  , so i gotta make some new coils ..

I've been running some numbers and the resistance  of each coil is bothering me a bit..

I've calculated that a 1.75" dia. coil of #20 gage wire , with a 0.855" hole and 0.49 thick , will have a resistance of 0.558 ohms.( about 55 feet).

with a 12 coil geny it comes to 2.23 ohms /phase.

so the Line to line resistance for Y (or star)is 4.46 ohms , kinda yucky.

but the line to line resistance for delta is only 1.51 ohms, much better..

so i think that i'm gonna go with delta because even if i double  wind each coil the line to line resistance ,of star connection ,is still 2.23 ohms .

any thoughts?

[hiker]

so whats the output on that alt. ifred

looks like one of my old desings as well--real cogger..

still workin on my 12" sawblade mill--just have to reninforce the base mount...

[willib]

Wild in Alaska , you had it right , for three phase ,in your blk.mag.layout photo , why change it?

you had 12 evenly spaced magnets for 9 coils , perfect..

but then you added 12 more, why

oh i see what happened..

for the dia. that you have , and the size of the coils , you probably could  have gone with 12 coils and 16 magnets.

because your coils should be right next to each other..and that is real important ..

can you change it?

[willib]

hiker this is a better design for your 12" dia saw blade..

it is designed for 16 , 2" x 1" neos.

the outer dia. is 12.266" but that is the stator the rotor is obviously within your 12" limit..



this design

as you can see there is very little  wasted space between the coils..

if ya want i can post all the dimentions..?

[willib]

One more question , as a rule of thumb , how thick should the coils be??

in relation to the strength of the magnet?

[hiker]

ran low on wire---next one will be made with bigger coils...

[willib]

They dont necessarily have to be bigger , just closer together, ie 12 instead of nine..

[hiker]

dan makes 1/2" thick stators--using neo"s

im thinkin about a 1/4" thick stator with 10" rotors for a ceramic powered alt..

down the road............and up the trail i go ....later..