Re: Microcontroller Edu Kit


"Jasen Betts" <jasen@xxxxxxxxxxx> wrote in message
news:6e81.4416537c.1d87@xxxxxxxxxxxxxxxxxx
On 2006-03-13, Laurie Forbes <nospam@xxxxxxxxxxxxx> wrote:

"Jasen Betts" <jasen@xxxxxxxxxxx> wrote in message
news:2529.4413dfd7.88932@xxxxxxxxxxxxxxxxxx
On 2006-03-12, Laurie Forbes <nospam@xxxxxxxxxxxxx> wrote:


It might be easier to get rotational speed from a magnet (or a few) on the
chassis interacting with a pickup on the rotor hub, getting altenator
voltage to the hub could require slip-rings which are
bound to be noisy... but they do provide a mor convenient power source..

but if you have them you may as well have only the motor on the hub....

Those are the two options I'm debating now. It would be nice to avoid the
slip rings but the battery needs a charging power source as well. It might
be feasible to mount a coil or two on the rotor and have them move past
magnet(s) on the stationary part (this would provide some charging current
as well as the rotational speed reading). If OTOH, slip rings are used and
everything except the motor is back of the rotor, at least three slip rings
would be required (two for power to the motor and one to feed back the blade
pitch position signal). Maybe the blade position could be imposed on the DC
power leads but that gets pretty complicated. With two slip rings only,
everything would have to be be located on the rotor.

or have a setup somewhat like a manual clutch where a bearing slides on
the
shaft. To the spinning part of the bearing is connected the levers
that feather the blades and the non-spinning part is driven by your
actuator, (a drill motor spinning a threaded rod etc...)

That's an interesting idea. I would be nice to keep all the electricals
back of the rotor, especially the battery (I don't know how well a battery
would stand up to the centrifugal and gyroscopic forces the rotor sees). A
rod in a hollow shaft driven forwards and back by the drill/threaded rod
might be workable (I think the mechanicals get more complicated though). I
also don't see right at the moment how to translate absolute rod position to
a signal that can be sent to the controller.

BTW, just received a free PIC16F sample from Microchip. I also ordered an
18F - don't know how many times they let you do that though :)

Laurie Forbes



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