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From: Terry King
Subject: Re: LEDs For Dummies? Pointers needed.
Date: Mon, 9 Dec 2002 21:48:39 -0500
Organization: Mountain ClockWorks
X-Newsreader: MicroPlanet Gravity v2.30.1784
> I am starting a simple project where I would like to control an LED's
> intensity from a computer.
The other suggestions were good. Point: The original
LSTTL output printer ports will current limit at about
20 milliamperes if you connect an LED from output pins
to ground. All the single-chip ports I found on the
old "Multi-IDE/Port" cards also limited at about 20 to
25 Milliamperes into a 1.9V LED. I've had groups
of kids blinkin' LED's on printer ports for years, and
as far as I know never killed a port!
I have some code on my site that controls and fools with
the printer port in many ways; One is/was a "Strobe"
program...mmm... (Looking at my old stuff...) Oh. OK.
"Strobe.pas" and strobe.exe in PARPORT.ZIP can set
lots of pulse widths etc, and display the values. You
need to read the Pascal source file to see how it all
works. You can also use infrared LED's and Phototransistors
(Radio Shack variety) to make a photogate to fire some
LED's as strobes. With today's high-brightness LED's this
should be pretty good. I used to trigger a modified
Radio Shack party-type strobe light from this software.
Start off with SEEBITS.EXE to turn a few bits on and off. AT:
titled, of course, "You Gotta Have Blinkin' Lights!!"
Regards, Terry King ...In The Woods In Vermont
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