The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "RP Henry"
Subject: Re: LEDs For Dummies? Pointers needed.
Date: Mon, 9 Dec 2002 14:54:44 -0800
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
"Brett" wrote in message
> Or you could use some diodes and resistors off the parallel port.
> Dataline to diode to resistor (2k-5k?) to LED to ground? The more
> you have on the brighter it gets.
> "Gregory L. Hansen" wrote in message
> > In article ,
> > Greg wrote:
> > >Hi,
> > >
> > >I am starting a simple project where I would like to control an LED's
> > >intensity from a computer. I have experience programming and with data
> > >acquisition cards. However, I am a newbie with LED control.
> > >
> > >Any pointers for good books or web sources for information on this
> > >to get me started?
> > More current makes the LED brighter, less makes it dimmer.
> > What else could you need? You have the computer with the digital to
> > analog converter. Connect the DAC output directly to the LED, with a
> > resistor in series so that at the highest voltage, the maximum allowable
> > current will be going through the LED. The LED itself will drop about
> > volts. The LED is an approximately zero resistance load, so you'll burn
> > it up if you try to run it without a resistor to limit the current.
Or you can run it without resistors with PWM brightness control, keeping the
maximum on time low enough to limit the average current to a safe level. Of
course, if you cycle is too slow, or you software hangs up with the current
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup