What's Wrong with my Diodes? - Page 4

 On Tue, 2 Jun 2009 06:36:07 -0700, "Ulysses"



Measuring is easy. Remove the insulation from the wire (I heat it in a
propane torch) and then measure the diameter of the bare wire with
either calipers or a micrometer.  For the replacement wire simply use
an AWG wire table.  Once you have the diameter, use pi*(d/2)^2 to find
the cross sectional area.  That's the old area-of-a-circle formula, in
case it looks wonky in ASCII.

In any event, don't spend a lot of time going for high precision here.
Wind the new coil on one pole, assemble the alternator and give it a
spin. If you don't get the voltage that you want, add or subtract some
turns as needed.

John

  On Mon, 1 Jun 2009 09:41:53 -0700, "Ulysses"


I hate that sh*t.  Do you know about the Wayback Machine,
http://www.archive.org  ?  Every so often they snapshot every website
on the net that they can get to.  Just take the URL of the website
that has that bullsh*t notice and plug it into the Wayback machine.
then you can look at the site before it was changed.

John

 

"post

SELLING

No, I've never heard of the Wayback machine, at least not since Peabody and
Sherman.  I'll take a look.

You're 10K generator appears to have a similar setup to the one you made
with the 4 HP Honda engine.  What kind of belt and pulleys are you using?
Maybe my whole problem is the alternator pulley.  I've been meaning to read
about different grades of belts but lately I'm lucky if I can be online long
enough to check my email.

I tried a chain drive (scary) and even a gear drive (really, really scary)
and the belt drive was the only choice by comparison.  At least if it throws
a belt it doesn't go very far or cause much damage.

For some weird reason Lawn Tractors are being given away with perfectly good
engines in them.  I have two that I got for free.  One has a 12.5 OHV engine
and the other has a 18 HP B&S twin cylinder.  It seems like they might make
good candidates for a belt-drive generator head plus they could be driven to
where the power is needed ;-)

 On Tue, 2 Jun 2009 07:04:16 -0700, "Ulysses"


I just used off-the-shelf industrial stuff from the motor shop.
Fairbanks pulleys, I think.  Whatever belts they sell. I did go
roughly by the book and tried not to overload the belts too much :-0.
The most usual cause of belts flipping upside down, other than being
completely and totally worn out, is the belt not being fitted to the
grooves.  Usually too large a belt that rides up mostly on top of the
groove.  That's why I wanted you to post some pix.  I wanted to take a
look at your setup and see if I recognize any of the common problems.

My favorite for applications like this is the cog belt but we didn't
have any of the right size hardware in stock and so I went V-belt. Cog
belts can transmit an amazing amount of power for a given physical
size and do so quietly and efficiently.

I've seen several "mobile" generator setup like you're describing. The
only problems I've seen relate to a) not putting the proper thrust
bearing in the generator when operated vertically and b) the
cheap-sh*t engine deck metal being so thin that belt tightness can't
be maintained.  Reinforcing the deck with some plate solves that
problem.

John

 

The belt rides higher on my alternator pulley than it does on my
engine/drive pulley.  The engine pulley I bought specifically for this
project (not the first pulley either) is for an A belt and that's what I've
been using, pretty much as short as is reasonable.  It sounds like the
alternator pulley may be my main problem.  I'll look again to see what's
available but in the past about all I found was either the same thing I have
now or a pulley for a serpentine belt.  The reason I had doubts about the
alternator pulley being the problem is because I used it for a long time for
producing 12 volts driven by my 4 HP Honda.  It just was not a problem.  But
I was only producing around 400-500 watts (most of the time) and for 48
volts it's about five times as much.

Meanwhile, back at the direct-drive... I was thinking of making a coupler
using perhaps 3/8" aluminum and four 5/16" bolts on each coupling.  For the
spider I was thinking of using 3/4" plywood.  The holes in the spider would
be just a bit sloppy and once it is perfectly aligned the gaps would be
filled with high-temp silicone and allowed to set.

Another option for direct-drive would be to build an alternator from scratch
such as the Piggot "axial flux" design.  Trouble is I'm not sure what to
start with for the shaft.  Maybe the old brake drum design would be simpler
as I think it uses the spindle to attach everything.  There just happens to
be an abandoned Volvo not far from here...

I'll try to take some pics today and maybe you can look at it and go
"there's your problem."  I always have a lot of trouble with digital
photos--if I can get the camera to turn on then I can't get the software
installed and have to put the SD card in another camera to read it blah blah
blah.  I still have all of my darkroom equipment but I figure by the time I
ever get around to setting it up again I won't be able to buy film.