From: MC elover (mcelover@yahoo.com)
Date: Wed Oct 24 2001 - 16:04:10 PDT
Message-ID: <20011024230410.26176.qmail@web10908.mail.yahoo.com> Date: Wed, 24 Oct 2001 16:04:10 -0700 (PDT) From: MC elover <mcelover@yahoo.com> Subject: LED 2, Frequencies Strikes Back
Hey all,
Well, it seems we have a pretty good consensus on the
LED problem--where the LED on the TV got brighter and
darker. WE here also thought that it must be a beats
phenemenon where the frequency of the flshing LED was
just slightly more or less than the scan rate of the
TV.
BUT ...
We're also convinced that (to borrow a phrase from
some science dude) it's more complicated than that!
Here's at least one reason: We turned off the lights
in the classroom and the whole thing stopped working.
I mean, the real LED was on and the one on the TV was
on, but none of that brighter-darker stuff happened.
Being smart science people, we got out a flashlight
and shined it at the LED--it started pulsing again.
But when the apparatus sat in the dark, there was no
pulsing.
Now, a funny thing about the camera we are using is
that is has some sort of automatic light adjustment
circuitry. From bright light to dark light, the
camera gives a nice image to the TV. One thing that
wasn't discussed in the last round of answers was the
science of the camera, and if the camera itself has a
scan rate.
My opinion is that the LED MUST be flashing at around
60 hz as opposed to an incandescent light bulb which
just glows regardless of the fact that it is getting
AC. In my mind, there is just no physical way for the
light from the LED to be steady, or even for the light
to go gradually from brighter to dimmer. It HAS to
turn on at a certain voltage and turn completely off
below that voltage (around 1.6 V). So, somehow the
TV/ camera combo must also be doing something (in the
dark classroom) that matches the LED blink rate. We
here are perplexed.
All opinions are appreciated.
--Eric.
P.S. here's a preview of LED part 3: little blue
lines that move around on the TV screen!!
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