From: "King Tut"
Subject: Re: Urgent help needed to blank monitor
Date: Mon, 4 Nov 2002 19:32:28 -0400
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You could use one of these two solutions:
1) Use an ON Delay relay to power up your monitor.
An ON DELAY relay is an electromechanical device that you can purchase at
your local industrial hardware store or an electrical supply. They come with
a knob and a dial and you can adjust the time it will take to close its
contacts after it has been energized.
PROS: Very easy to use.
CONS: If the boot up process takes too long due to an unusual circumstance,
the monitor will start displaying before your application is running.
2) Create a circuit controlled by your serial port. You can use a small PIC
to receive a certain word or words to order it to open or close a relay,
that would energize your monitor.
Hope it helps....
"Ulrich Peters" wrote in message
> I need assistance from somebody with knowledge in electronics. I am a
> programmer, and I am facing a problem which is a little too much for me.
> I worked in electronics (and even started coursing electronic
> engineering) in the past, but I changed my course to information
> I wrote a program, which run in a customized PC, using a customized
> keyboard, in a kiosk-like box. The software runs just fine, but now the
> company I wrote that product for, requires that there should be a blank
> monitor while the operating system loads (Windows 2000), and the monitor
> should be turned on only when the application is already running full-
> There is no way to do this just with software. Until the software
> starts, shutting down the monitor, the boot process will be shown, so I
> think that the only solution is some electronic circuit which I can
> control with my software.
> My solution I came up with is as follows: I am already able to write a
> certain bit pattern on the parallel port, so I would take four bits of
> that parallel port and feed them into a 74LSxxx to make some digital
> logic, to finally get one logical ON (+5V) if the input bits are set
> Then I would connect that logic high to the gate of two thyristors (or
> should it be triacs?) to make the vertical and horizontal sync signals
> reach the monitor.
> It works like this: I pick the vertical and horizontal sync signals from
> the output of the video port, connect them to the input of the
> thyristors, and when I trigger the gate, the signal becomes available at
> the output pin of the thyristor. From there it will be connected to the
> video connector.
> Without V/H sync, the monitor should stay blank (as it does when the
> energy saver is active). I hope that this way I could control the moment
> I want the monitor to be activated. No more boot process on the screen,
> I would trigger the gate only when my software is already running.
> Ok, this is my idea, and now I need some help. Can somebody tell me what
> components would be the most appropriate for this circuit? I think that
> the currents of the sync signals are pretty low, but I don't have any
> instruments to measure them. What thyristor/triac could I use, and how
> should I connect the TTL output to the gate? (If this is a good idea at
> all. If you see that this won't work at all, please tell me.)
> Any help would be appreciated. If you want to write me in private,
> please use the address upeters at mq dot srv dot br, or upeters at
> spamcop dot net for your reply. If you are a professional in the US and
> would like to help me, I could pay you with a money order... Of course I
> will accept free assistance as well. :-)
> Sao Paulo, Brazil