Jeff,
Thanks for the reply.
True 'auto-tune' would require Ip, Ig, RF and other inputs back to the
controller(s), which may require more work than my lazy self is willing
to do at this point. I do, though, like the "preset" concept. As you
point out, that could be implemented fairly easily. Thanks for bringing
it up.
I'm also considering gearing down a shaft with a pointer attached that
would break an optical interrupter at both ends of travel. With those as
references, I wouldn't need the pots. Down side there is that those
might be tricky to align and good practice would require me to run each
cap and the inductor out to full range and back to zero stop each time
the controller(s) booted to verify operation and set the "soft" stop
references.
Back to the pots, as long as I implement some kind of software monitor
to track how much the divider "jumps around" with given movement, (to
track pot wear) I could assume the ADC level references were static. In
my book, simpler is gooder. :-)
Tnx & 73,
--jim
Jim Barber, N7CXI
On 8/8/2011 1:22 PM, Jeff Blaine wrote:
> Jim,
>
> I don't have an answer for your actual question. But the pot idea is good
> for another reason. In that would open the door to an
> auto-tune kind of option (or at least, the ability to record presets which
> via the ADC input, could be used to set the cap via the
> stepper). If your drive and antenna loads are stable, that would be very
> cool and not too complicated to code up.
>
> 73, Jeff ACØC
> www.ac0c.com
>
> -----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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>
>
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