Exact match. Not showing close matches.
'[OT]: Wind turbines, was How can I most easily cut'
|On Thu, 23 Jun 2011 12:09 -0700, "William Chops Westfield" wrote:
> I want to do something like this. Some sort of convenient semi-
> tubular piece of trash mounted on a discarded CD drive spindle motor
> (or one at the top an one at the bottom?), perhaps with much of the CD
> drive mechanics still intact. Put it on the roof and measure the
Or flip it over so the armature is stationary and the motor body spins
and you can have a wind-powered propeller clock.
Here's a clock that uses the stepper motor from an Apple ][ disk drive
for power, the motor body is spun by belt drive from the spindle
Or you could make a wind-powered LED anemometer :)
But there'd be inaccuracy because of the load of the power generated.
-- http://www.fastmail.fm - Send your email first class
On 23/06/2011 20:32, Bob Blick wrote:
On the cat door Bob - what exactly does it do and how? Does it ID the cat(s) or do you only have one?
I'm asking because we are total "cat people" here (i.e. the cats own the house and are tolerating our presence)
We already have an electric cat door purchased from a small L.A company, but I was thinking it would be nice to know things like which cat (we have 4) comes in/out and when, we have had a few situations where it would be useful to have that information.
I'm thinking PIC with some wireless ethernet module to network, or cheap radio module at either end to USB. For the ID it could be RFID, IR, optical recognition, etc.
It's just a "rainy day" project idea, that will be filed alongside the other hundred things I want to do when I have a spare minute, but any info on your project would be appreciated.
On 23/06/2011 23:54, Oli Glaser wrote:
> I'm thinking PIC with some wireless ethernet module to network, or cheap
> radio module at either end to USB. For the ID it could be RFID, IR,
> optical recognition, etc.
Most RFID apps are stupid (human passport, Credit card).
But for Cat Chip it's a good idea. I expect that's what Bob has. As I think standard pet "chipping" is RFID/NFC type stuff anyway or else how are they read?
They just can't be bothered using the cat's paw sized keypad and pressing the personal PIN. You'd easier persuade a Rook to do that. I saw film of a pet one that figured keys and locks. It even experimented with the car ignition
On 6/23/2011 3:32 PM, Bob Blick wrote:
I would not have considered a stepper motor.
The cheap brush type hobby motors work fine. When I was working for IBM I had
a few occasions to mechanically attach one of these motors to a spinning shaft
and scope the output. The voltage was a good representation of the velocity but
the value was in the variations. You can see gear lash, binds and any rattles in a mechanism.
*John Ferrell W8CCW*
*'A man's feet should be planted in his country, but his eyes should survey the world. '*
|On 24/06/2011 00:17, Michael Watterson wrote:
> On 23/06/2011 23:54, Oli Glaser wrote:
>> > I'm thinking PIC with some wireless ethernet module to network, or cheap
>> > radio module at either end to USB. For the ID it could be RFID, IR,
>> > optical recognition, etc.
> Most RFID apps are stupid (human passport, Credit card).
> But for Cat Chip it's a good idea. I expect that's what Bob has. As I
> think standard pet "chipping" is RFID/NFC type stuff anyway or else how
> are they read?
I was thinking if Bob only has one cat then it may be a simpler setup, like a magnetic tag to open the door and confirm it isn't a raccoon/skunk, then register in/out and time. Sure Bob will confirm either way soon though.
You are right about the pet chipping being RFID:
> They just can't be bothered using the cat's paw sized keypad and
> pressing the personal PIN. You'd easier persuade a Rook to do that. I
> saw film of a pet one that figured keys and locks. It even experimented
> with the car ignition.
We have one cat that we consider to be an intellectual giant. He always appears to be wrestling with some deep cosmological problem.
Only trouble is we haven't yet figured out a way to translate from "Cat" to English and extract the information from him.
I'm quite sure he could operate such a key pad. However, I think that he would probably consider the pressing of keys simply to come and go to be beneath a cat of his spiritual intensity.
> I would not have considered a stepper motor.
PM steppers work well as low power alternators.
They have many more poles than a typical small BLDCM do higher output
per rev (danger ...).
They are however usually very coggy (high saliency) which makes them
harder to start in very low energy input situations.
In some cases that matters, often it doesn't.
Lack of brushes is nice.
Any BLDCM will work for many values of work.
|On Thu, Jun 23, 2011 at 10:31 PM, RussellMc <gmail.com> wrote: apptechnz
> > I would not have considered a stepper motor.
> PM steppers work well as low power alternators.
> They have many more poles than a typical small BLDCM do higher output
> per rev (danger ...).
> They are however usually very coggy (high saliency) which makes them
> harder to start in very low energy input situations.
> In some cases that matters, often it doesn't.
> Lack of brushes is nice.
> Any BLDCM will work for many values of work.
I've been expending a little mental energy on permanent magnet alternators
for "a while now". Obvious problem is no inherent method of regulation, i.e..
output entirely dependent on shaft speed and load.
Commonly found on motorcycles. Typical regulator circuit is (functionally,
at least) a massive zener diode clamping at battery float charge voltage. OK
ish for most engine based applications (lots of power to spare), not
acceptable for small, low-power, high efficiency applications.
Seems there would be a useful crossover from solar PV panel tech here.
Adding some variation of the Maximum Power Point controller could
improve efficiency markedly and allow useful generation over a much broader
range of wind conditions.
> I've been expending a little mental energy on permanent magnet alternators
> for "a while now".
As have I.
> Obvious problem is no inherent method of regulation, i.e.
> output entirely dependent on shaft speed and load.
> Commonly found on motorcycles. Typical regulator circuit is (functionally,
> at least) a massive zener diode clamping at battery float charge voltage. OK
> ish for most engine based applications (lots of power to spare), not
> acceptable for small, low-power, high efficiency applications.
If you can tolerate the voltage you can let the bus float to whatever
it wants and buck regulate it to desired output. Efficiency can be
excellent. At light loads conversion efficiency is unimportant from an
energy use point of view. When loaded heavily it approaches the
loaded design value. Unless you boost, design Vout needs to be greater
than system voltage - usually a battery - at all wind speeds where
power is required. Otherwise a system which has say 10% Voltage
headroom at 10 m/s may have -45% headroom (eg no charge) at 5 m/s.
Simplistic systems use star delta switches and direct battery
connection apart from a "switch" so that Vout is boosted at low speed
(Star) and lowered above a certain point (Delta). Joe will tell you
what fun these can be.
As the need to dump energy or limit energy used usually occurs at high
wind speeds you can consider PWM shorting the alternator. This
produces variable braking and both partially removes V_alternator from
adding to Vout and limits power by braking.
If you are relying on shorting to keep WT speed down to prevent cubed
law runaway you want to start "early enough". Above a certain speed
short circuited braking energy does not match V^3 wind input and the
gates of hell (nor Microsoft) shall generally prevail against attempts
to prevent self destruction.
Very low power systems can be over-engineered to TRY to survive
serious overspeeding but the cbe law means that real world products
usually need some other mechanism. This can be eg tilt back, tilt
sideways, feathering, blade stalling, winch it down when a storm's
coming, etc. Blade stalling is a good trick if you can manage it and
an even better one if you can guarantee it come what may. The default
speed regulation mechanism is fly-apart, which come in many
MPPT Maximum Power Point Tracking) can be used with WTs with variable
success. More challenging than solar due to, again, the cube law with
Velocity energy input, the lack of a known energy level (unlike solar)
and the addition of extra factors - eg solar has cloud pattern changes
etc but HAWT (Horizontal Axis Wind Turbine) has slewing response,
rotor inertia and energy storage,
> Seems there would be a useful crossover from solar PV panel tech here.
> Adding some variation of the Maximum Power Point controller could
> improve efficiency markedly and allow useful generation over a much broader
> range of wind conditions.
Crystal ball lookahead helps in gusty conditions (especially with
HAWT). Some have been known to use a ring of "incoming sensors".
Sounds bizarre but makes sense as they get bigger. VAWT(Vertical Axis
.....) regulation is often by wing stalling , or claimed to be (and
you'd better hope so if you don't want to have to wonder where your
blades have gone). Lift style VAWTs have most of the problems of
prop-HAWTS and as an eg Darrieus VAWT can be designed to run at a TSR
of up to about 5:1 they can get very exciting above max design wind
Power at wind speeds much below design for a site is low to very low
and largely not worth putting much $ effort into.
eg a 10 kW at 10 m/s system makes about 1.25 kW at 5 m/s (12%) and
under 300 Watts (3%) at 3 m/s. At 1 m/s it would notionally make about
10 Watts but is unlikelt to turn and even less likely to start.
Real people choose real sites* with a Weibull distribution that allows
closish to design power a lot of the time and fewish periods with very
low power. Sites with broad flat Weibull distributions make getting
consistently good power out and not failing to fall down both hard.
* Real sites are generally as high as possible, away from anything of
similar height and thus well away from turbulent flow, not mounted on
anything where acoustic coupling is liable to lead to midnight axe
Entrepreneurs, investors, starry eyed idealists and people who don't
know how to use Gargoyle keep rediscovering VAWTs as the answer to
everything. They proclaim their ability to work in low height
turbulent urban locations, on roof lines, in courtyards and more.
raise money, have fun and largely fade gently from the scene. Some
people build real world VAWTS, charge really really really high prices
for them and stay in business.
Helix seem to have survived longer and done better than many. AFAICT,
.... where vibration ...
Wow. Silly , but wow.
Mark E. Skeels
"The default speed regulation mechanism is fly-apart, which come in many interesting forms."
:-) Tickles my funny bone.......
> "The default speed regulation mechanism is fly-apart, which come in many interesting forms."
> :-) Tickles my funny bone.......
Especially if you stand too clos
More... (looser matching)
- Last day of these posts
- In 2011
, 2012 only
- New search...