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Subject: Re: LCD backlight Dimmer circuit
Date: Sat, 28 Sep 2002 12:41:53 -0700
Organization: SCN Research of Tigard, Oregon, USA.
References: <firstname.lastname@example.org> <email@example.com>
NNTP-Posting-Date: Sat, 28 Sep 2002 19:43:06 +0000 (UTC)
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Depending on the type of LCD, you'll need to consider the "scan" frequency
of the LCD and interactions with the backlight frequency PWM rate....
"davidjudy" wrote in message
> "Richard Soennichsen" wrote in message
> > That is a good idea. The circuit has a microcontroller with unused port
> > pins. Maybe I will drive the backlight through a transistor all the
> > when the input is low. I have an timer interrupt every 1ms. I could
> > the input and if high modulate the transistor to dim the backlight.
> Fine if this is a 1-off for personal use. If it's a production design you
> need to consider the EMC generated by 1kHz switching of 1-200mA/12V. The
> things we could do with careless abandon some years ago are now mere fond
> memories. (Just like being able to say 'gay abandon'!)
> > Richard
> > "Sir Charles W. Shults III" wrote in message
> > news:firstname.lastname@example.org...
> > > Make a variable duty cycle oscillator (like with a 555 chip) and
> > the
> > > output into a transistor. That transistor will drive the LED
> > Varying
> > > the duty cycle will change the intensity.
> > >
> > > Cheers!
> > >
> > > Chip Shults
> > > My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
> > >
> > >
> > >
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