fayne@Tellabs.COM (Jeffrey Fayne) (05/09/90)
Here's an unusual one:
A friend of mine develops in-house PC-based test equipment for a local
manufacturer. He is developing a system that requires the use of two
monitors (one is an EGA color and the other a monochrome). What he would
like to do is have the mono monitor next to the PC for the test operator to
use, while the color monitor has to be approx. *100 FEET* away.
The question he has is:
Will a typical EGA card (a Paradise card in this case)
drive a monitor that is that far away?
If not does some sort of buffer/driver device exist to solve his problem?
Any ideas or pointers to products would be appreciated.
Thanks in advance,
Jeff
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F-14 | _ | | Jeffrey M. Fayne
Tomcat | /^ ^\ | | Tellabs, Inc.
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_____________________________________________________________________________medici@elbereth.rutgers.edu (Mark Medici) (05/10/90)
In article <2555@tellab5.tellabs.com> fayne@Tellabs.COM (Jeffrey Fayne) writes: > >[edited] ...that requires the use of two >monitors (one is an EGA color and the other a monochrome). What he would >like to do is have the mono monitor next to the PC for the test operator to >use, while the color monitor has to be approx. *100 FEET* away. > >The question he has is: > > Will a typical EGA card (a Paradise card in this case) > drive a monitor that is that far away? Possibly, but I wouldn't do it. > >If not does some sort of buffer/driver device exist to solve his problem? May exist commercially, but a simple solution is: Get two 74S244 buffer IC's. Don't use 74LS' series, since they don't put out much power. If you want, you can try straight 74244's, but you will probably benefit from the better waveshapes coming out of the 74S244 at least on the monitor end. Stick one of the chips on the PC end of the cable, to reduce the likelyhood of overburdening the output buffer on the EGA card. You might want to put pull-down resistors on the input of this buffer. The other 74S244 buffer on the display end of the cable to clean-up the waveform. Use a 6.3 volt, wall mount power supply with a 6V volltage regulator and some capacitors for your power supply. If you feel daring, you can shoot this down the signal line on an extra set of wires (e.g., use 12 conductor instead of 9). In between, use low capacitance NON-TWISTED, UN-SHIELDED cable. If you use shielded and/or twisted-pair cable, it will mess-up your signal; it might still work, then again, it might not. You might also need to stick a third 74S244 in the middle of the cable. Be forewarned, the FCC might not like this little hardware hack. Also, I take no responsibility for this. It should work -- I made many similar devices for driving multiple monitors from a single EGA card up to 50 feet away, and used this same design. Never had any problems, but that's just me. ---------------------------------------------------------------------------- Mark Medici/SysProg3 * Rutgers University/CCIS * medici@elbereth.rutgers.edu ----------------------------------------------------------------------------