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Re: Fertilizer pump fix...
>There are simple flow indicators that use a little ball in a donut of
>tubing to show flow. The ball goes zooming around in the donut when a fluid
>goes through. While I doubt these are very precise, perhaps your pump is
That may be how this one works, but that little ball/donut/whatever is
certainly not there. Probably part of the consumables since it would be
in contact with the fluid.
>Most of the metering pumps I've seen use synchronous motors that
>have rotation rates that are linked to the line frequency of their power
>supply.
I'm pretty sure this is stepper motor based, though I haven't opened
it up yet. The pump head moves a very small amount, maybe a few degrees
each "pulse". The frequency of the pulse depends on what I set the digital
control to. Lower the ml/hr, the less frequent the pulse occures.
>Thinking about it
>though, I would suspect a hospital grade device like you describe wouldn't
>have a problem with running all the time since I would suspect that long
>runtimes would be common in the device's intended operation. The whole duty
That makes sense... Since it has a built in battery backup, it would seem
to indicate that it is made to keep running whatever happens. I guess my
best
bet would be to see if it gets hot.
Here is what I have figured out for the benifit of any one else who might
try this... I'm 99% sure its infra red, since pointing my vcr remote at the
sensor windows keeps it from tripping. Blocking the sensor does not work,
and
foil doesn't seem to work (probably just didn't get it right). So, a 555, a
few
resisters, caps, 9V battery, and an infra red LED, and I think I'm in
business.
Should run forever on a 9V battery too... I think I even have a 555 part
calculator for my Palm III so I don't have to look it up. :)
Then I gotta calibrate it (since I don't know what diameter tubing its
expecting)
and calculate the dilution for my fertilizer. :)
Thanks for the help!
John