Subject:
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re: IR frequency / o'scope adjustments
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 31 Mar 1997 15:27:51 GMT
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Original-From:
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Jim Harsh <HARSH@nospamLANL.GOV>
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Viewed:
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1576 times
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At 12:00 AM 3/30/97 -0500, you wrote:
> Connect the ground from the oscilloscope to the HB ground (anyone).
> Connect the V from the oscilloscope to the + end of the LED driver (or the
> annode of the LED if it's connected).
> Adjust the oscilloscope until you get a visible square wave sequence. It
> may not be exactly square, but it'll do. Measure the period. (time distace
> of ONE cycle) [Note: this is a V vs. t depiction]
> Divdide this period into 1.
> The result is the frequency.
>
> Sorry about the ambiguity in "adjusting" the oscilloscope. I lack some
> good technical terms. I must say, I just turn a couple of knobs here and
> there. :) Perhaps someone with a better understanding can explain
> better.
You want to trigger off of the signal, or maybe the line; the knobs to turn
are generally marked "slope" and "level" or something close to this. I usually
use a positive slope, I just like the signal to be going in a positive direction
at the left of the trace. The level is adjusted until the signal is stable. The
time of the sweep vernier, if there is one, is in the calibrated position
and the time of sweep step knob is adjusted till just at least one cycle is
displayed, the vertical position is adjusted to center the signal up and
down, and the horizontal position is adjusted so that the first zero
crossing is at the far left of the engraved scale. The level adjustmentis
adjusted so that the sweep triggers before the zero crossing to get the most
signal on the screen.
This is probably still confusing. In the tech school I went to we spent
about a week on how a o'scope works and how to use one. The fastest way to
learn a o'scope is to sit down with someone and have them show you. Once you
know the basics, then you have to deal with different manufactures having
different labels and layouts of the front panel.
Good luck
Jim
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