CHEAP XYZ PLOTTING
Having invented with Colin my colleague the
Fluxgate magnetometer, a sensitive electronic instrument that
detects magnetic forces / flux, I needed to find a
way to produce easily and cheaply accurate pictures of Magnetic flux,
(Not a guess from a small sample or assessments with iron fillings).
Because we had had some surprising results on a project.
Well I am fairly good with the basic Computer
i.e the BBC machines and of course the printers,
"THAT’S IT" use an old printer. I had an old
large printer that was ideal, the paper feed was from
the back and a magnet arrangement was placed on the paper so
when the printer moved up one line the magnet moved
one line. It had a heavy and strong print head. I fixed an
arm to this and the Fluxgate probe to that.
The rest was a matter of BASIC programming
To SAMPLE LINE 1.
TAB the print head to move to
Tab(1) and the computer to take a reading from the
probe, tab(2) read probe tab(3) read probe. Up to
tab(40) then move paper up one line (this moves magnet on a line).
SAMPLE LINE 2 and so on up to SAMPLE LINE 40.
You have now taken 1600 samples
precisely at the individual character positions. My BBC
computer was fed via the input port a varying voltage
from the Fluxgate electronics between 0 and 1.5v and it stored
dependent on that voltage a number between 0 and 65520.
Now you have to get the computer to change
these large numbers into single digits otherwise your
printout will look like garbage, simply divide by 7280
and take only the first decimal point. This gives a scale
of 1 to 9. With some more simple mathematical
equations this can be enhanced
Then get the computer to print out the readings taken
In order to prove my theory that air being drawn
into a common fan inlet is not completely round this being
connected with my cyclone experiments, I needed to see
a photograph of the air movement and or pressures at
the inlet of a fan when working. IF you haven’t already
heard it I have penned an extra phrase. “Necessity may well
be the mother of invention but poverty is the farther of
adaption” and, being a poor inventor, I looked around for something
to adapt. I had available the Fluxgate magnetometer , I
also had an old instrument that used a small diaphragm so
all I needed was something to very accurately move a
petotube in a cubed grid in front of a working fan.
If you want more details Email me
BY WIZARD MERLYN M.M.C.
@COPYRIGHT1994
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