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From: "N. Coesel"
Subject: Re: Urgent help needed to blank monitor
Date: Tue, 5 Nov 2002 22:35:47 +0100
Organization: Planet Internet
NNTP-Posting-Date: 5 Nov 2002 21:37:18 GMT
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
"Ulrich Peters" wrote in message
> 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.
This will work OK if you use a small relay. Be sure to let the latch reset
when the computer is powered (small capacitor and 10k resistor) and drive
the relay by a transistor. Be sure to put a diode accross the relay.
Reply to: nico nctdev nl @ .
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