Very interesting, Martin. Thanks!
This leans back more toward what Al was talking about, but keeping track
of the states becomes Someone Else's Problem. :-)
I'll check these out.
73,
--jim
Jim Barber, N7CXI
On 8/8/2011 2:46 PM, Martin A Flynn wrote:
> Jim,
> Have you considered using an absolute position encoder on the stepper shaft?
> This particular family will track up to 192 shaft turns, sending a a unique
> code for each position: http://www.stegmann.com/product/absolute/hollow.html
>
> Money permitting this is what I will be using on my GS35B project.
>
> Martin
>
>
> -----Original Message-----
> From: Jim Barber
> Sent: Sunday, August 07, 2011 4:45 PM
> To: Amps@contesting.com
> Subject: [Amps] "Best" limit indicators for multi-turn, shaft-driven gadgetry
>
> I've reached the point where I need to decide whether or not to make my
> YC156 project amp "remote". Because of other interests, I already have a
> good selection of larger stepper motors and drive electronics, and a
> good feel for how to put it all together.
>
> What I don't have is a good, simple limit stop/reference concept for the
> vacuum caps and (possibly) roller inductor. I've used drive screws and
> leaf switches in the past, but don't like the mechanical sloppiness and
> complexity. I've also seen optical interruptors used in place of the
> leaf switches, but still don't like the mechanical complexity of the
> whole drive screw, platform and guide assembly.
>
> My favorite candidate at the moment is a high-quality 10-turn pot in the
> timing belt path for each shaft, "gearing it down" so that (for example)
> a vacuum cap that rotates 13 turns end-to-end would run 8 or 9 turns at
> the pot shaft. Using regulated 5VDC, I could then apply the output of
> the (pot) divider to a 10-bit ADC. Note I already have ten 10-bit ADC
> inputs at each control processor, so that isn't as much of a
> complication as it might seem.
>
> Any thoughts or suggestions?
>
> Thanks,
> Jim N7CXI
>
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