Blinking LED circuit

[markw at mohawksoft.com]

Well, the "easiest" thing to do is write a quick Linux program and run the
LEDs off your printer port.

Google for paralell port HOWTO
Here is a pin-out: http://www.mohawksoft.com/techtips/parport.html

If you run the program as root, you can write to the parport directly.

Using the computer has the advantage of virtually infinite
programmability. Of course, if you need absolute integrity of the timing,
then a computer would be bad, but then again, so would anything but
precision freqency generator and a counter/divider circuit.

You could also monitor the port and use it for data acquisition.


From: Doug Sweetser <sweetser at TheWorld.com>
To: discuss at blu.org (Boston Linux Users)
Subject: Blinking LED circuit
Date: Fri, 24 Sep 2004 08:36:18 -0400

Hello:

I need a pair of red blinking LEDs for a video project, one where the
first blinks, there is a 0.5 sec gap, the second one goes, then a 3.5
second gap, and then that cycle repeats.

In an hour of Google time, I can see how to get one blinking light,
and a pair at two different frequencies.  I need a pair of lights at
the same frequency, but displaced by a bit of time.

Perhaps the easiest thing to do is make a pair of single blinkers,
hook them to the power supply independently, and do that until the
blinking pair looks good.

If this is easy/fun for any EE folks in the audience, I would like to
hear from you.

Thanks,
doug