Subject:
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Re: Some help or advice requested
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Newsgroups:
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lugnet.technic
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Date:
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Sat, 23 Jan 2010 10:39:00 GMT
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Viewed:
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21176 times
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In lugnet.technic, Owen Dive wrote:
> Hi all.
>
> I am currently working on a project (to be revealed in due course!) and I've
> come across something of a stumbling block. I have a tray that is constrained to
> move in one dimension, and a series of short liftarms under the tray, all
> rotating in phase with each other, and placed such that once per rotation, they
> connect with the tray (ok, so the tray can move vertically as well, but only a
> little bit!) and move it along a specified distance. So far so good. What I need
> is for the motor to change direction when the tray has reached the limit of its
> travel, and to have such a mechanism at each end of the track, so the tray moves
> back and forth for as long as power is supplied. Make sense?
>
> Now, this would be trivial to do using a couple of sensors and a computer (RCX
> or NXT or similar), but aside from the fact that I don't own any sensors for my
> RCX, I have committed to using only electromechanical principles. Until now, I
> have been trying to achieve this using a pole reverser switch, but have run into
> the problem where the switch turns the motor off at the top of travel, and the
> tray doesn't have enough momentum to finish the job itself.
Last year I built a pneumatic excavator module for a GBC display exactly for
this reason: doing it with an RCX would have been like cheating when it could be
done mechanically :D
As for your 'problem', I've been turning this over in my mind for some time and
for now the best solution I've come up with involves an extra switch and an
extra motor:
The tray should throw the switch for the extra motor which in turn will change
the switch for the tray. I'm still looking for a better solution though.
Jetro
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Message is in Reply To:
 | | Some help or advice requested
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| Hi all. I am currently working on a project (to be revealed in due course!) and I've come across something of a stumbling block. I have a tray that is constrained to move in one dimension, and a series of short liftarms under the tray, all rotating (...) (15 years ago, 19-Jan-10, to lugnet.technic)
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