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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Mon, 25 Jan 2010 18:23:49 GMT
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Viewed:
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20035 times
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> I have been asked for some pictures of what I am working on (very much
> prototypes at the present - don't expect anything elegant). • ...
> Hope that helps to clear things up - keep the ideas flowing!
>
> Owen.
Well, seeing your pictures, I can't help wondering: do you actually need the
tray to change direction as soon as it hits the end?
If not, you can use a much easier solution: just power its motor for a given
amount of time in one direction, then the same amount of time in the other
direction, and so on. If your tray needs, say 14 seconds to move to one side,
just apply power for 16 or something.
The only drawbacks are that you need to be sure that it's not a problem to
continue to apply power when the tray is at the end (which you can do using a
clutch wheel although seeing your pics I don't even think you need anything);
and that the timing doesn't need to be too exact.
The advantage is that you don't need the power reversal mechanism to depend on
sensing anything - so that it just becomes a matter of having another motor
reverse polarity every x seconds.
I've used such a setup with one PF motor to drive a PF switch, which would
reverse regularly; the time between reversal being just a little more than what
another motor needs to drive a linear actuator from one end to the other. No
sensor needed, and the linear actuator just went back and forth.
I've also seen posts of someone doing this to power a back-and-forth train,
while diode-rails at the ends to stop it until the next power reversal. No need
for sensors or anything.
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Message has 1 Reply:
 | | Re: Some help or advice requested
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| (...) You're quite right in that there's nothing in the pictures to suggest that having the having the motor running after the tray reaches its stop would be a bad idea. However, that would be disastrous for the rest of the machine - think of a (...) (14 years ago, 25-Jan-10, to lugnet.technic)
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Message is in Reply To:
| | Re: Some help or advice requested
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| (...) SNIP (...) I have been asked for some pictures of what I am working on (very much prototypes at the present - don't expect anything elegant). (URL) is the track for the tray, and the drive mechanism. As the axle at the front (bottom) of the (...) (14 years ago, 22-Jan-10, to lugnet.technic)
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