On Saturday 04 August 2007, Jon Elson wrote:
>Mark Pictor wrote:
>>>>The nice thing about resolvers is that they are very rugged -
>>>
>>>with no
>>>
>>>>electronics in the resolver itself, they can handle high
>>>
>>>temperatures,
>>>
>>>>coolant, and other abuse that would kill an optical encoder in
>>>
>>>short
>>>
>>>>order. The bad thing about resolvers is that the circuitry to
>>>
>>>generate
>>>
>>>>the sine wave reference and interpret the resulting signals is
>>>
>>>usually
>>>
>>>>complex and expensive.
>>>
>>>And could now be put in one IC.
>>
>> Ahhh, but they are still big bucks... somebody was selling surplus
>> R/D chips on ebay a couple months ago for $350/each.
>
>They used to be expensive. But, Analog Devices recently came
>out with the next generation of this, the AD2S1200, $18 in
>single quantity from Digi-Key. It not only generates absolute
>position, but it puts out a simulated quadrature signal.
>
>Jon
With the eval board at $150, and I doubt it comes with the rotary coil set,
that raises the price of that toy quite a bit unless someone here wants to
see if they can squeeze it into say $50 for a run of 100 or so.
With the accuracy claimed, I can see it will take some means to diddle coil
positions while the spindle is locked very accurately at 90 degree increments
in order to achieve the accuracy claimed over a full revolution. This
obviously is going to make the mechanical portion pretty expensive too.
Then the question is, can emc2 interface, via a separate parport, the rather
copious amount of data this thing can produce on demand, and make use of it
at usable spindle speeds? That would appear to be easier on the software
than trying to use the quadrature signals since their rep rate can get well
into the megahertz range, pushing the interrupts right over the edge.
A good "what if" question.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Two brothers, Mort and Bill, like to sail. While Bill has a great
deal of experience, he certainly isn't the rigger Mort is.
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