mcorbin@oucsace.cs.OHIOU.EDU (Max Corbin) (08/13/90)
Hello everyone! I have several crt boards and tubes at home and I would like to use them as video monitors. The problem is that they us Vertical sync, Horizontal sync, and composite video inputs. Question -- Does anyone out there have a circuit that will get these signals out of a NSTC video signal? Any help would be appreciated. Thanks in advance! -- mcorbin@oucsace.cs.ohiou.edu +-----+---\ +-----+ CS559@ouaccvmb.bitnet | | | | -- >| ---+ "Flat possums never DIE!" -RoADkIll +-+-+-+---/ +-----+
bwhite@oucsace.cs.OHIOU.EDU (Bill White) (08/14/90)
In article <1702@oucsace.cs.OHIOU.EDU> mcorbin@oucsace.cs.OHIOU.EDU (Max Corbin) writes: >Hello everyone! Hello Max. > > I have several crt boards and tubes at home and I > would like to use them as video monitors. > The problem is that they us Vertical sync, > Horizontal sync, and composite video inputs. > > Question -- Does anyone out there have a circuit > that will get these signals out of a NSTC video > signal? Yep. I built one once. I've still got the schematic and plans and such. > > Any help would be appreciated. > > Thanks in advance! You're welcome in retrospect. >mcorbin@oucsace.cs.ohiou.edu +-----+---\ +-----+ >CS559@ouaccvmb.bitnet | | | | -- >| ---+ >"Flat possums never DIE!" -RoADkIll +-+-+-+---/ +-----+ They just wear down. :-) (INEWS fodder) . . . . -- | Bill White Internet: bwhite@oucsace.cs.ohiou.edu | | MURPHY'S EIGHTH COROLLARY: | | It is impossible to make anything foolproof because | | fools are so ingenious. |
myers@hpfcdj.HP.COM (Bob Myers) (08/22/90)
> Question -- Does anyone out there have a circuit > that will get these signals out of a NSTC video > signal? Assuming that you have an NTSC *baseband* signal to work with (meaning that it's already been demodulated off the RF carrier): 1. Several ICs are available which do just this; some good examples are found in the Motorola _Linear_and_Interface_Integrated_Circuits_ data book (Section 9). Assuming that you want to go from NTSC video to RGB outputs, look at the TDA3330 color processor. 2. On the other hand, if you're just talking about monochrome, stripping the sync off is relatively easy. There's really no need to strip off the sync prior to sending the signal to the video amplifier, as the CRT is already in blanking during this period. (NOTE: This assumes that the monitor includes some form of a "DC restore" after the video input, to detect the blanking level on a composite video signal.) You will need a sync separator to generate signals for the deflection circuit, though. The typical way is to feed the composite signal (possibly inverted, or sync positive, depending on your design) to a transistor that is biased in cutoff, such that the sync tips turn the transistor on. In other words, only the sync tips get through. What you get out is composite sync - both horizontal and vertical together. These can be separated by using high and low pass filters, as the H and V frequencies are quite far apart. Actually, an HSYNC input is often quite happy receiving composite sync, as it's just looking for edges. Therefore, you might be able to simply low-pass filter the CSYNC signal to make VSYNC. Buffer, etc., to get to your desired level (TTL or whatever). Which brings up another point: 3. Are you certain that your CRT/associated stuff is set up for NTSC video rates? (60 Hz *interlaced* vertical, about 15.75 kHz horizontal?) If these are "computer surplus", they may not run at these rates, which are slower than many of the standard timings used for computer displays. Good luck! Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers@fc.hp.com | sentient life-form on this planet.
domenic@defran.UUCP (Domenic DeFrancesco) (08/26/90)
>In article <1702@oucsace.cs.OHIOU.EDU> >mcorbin@oucsace.cs.OHIOU.EDU (Max Corbin) writes: > > I have several crt boards and tubes at home and I > would like to use them as video monitors. > The problem is that they us Vertical sync, > Horizontal sync, and composite video inputs. > > Question -- Does anyone out there have a circuit > that will get these signals out of a NSTC video > signal? Consider using a LM1881 Video Sync Separator IC from National Semiconductor. Its simple to use. This 8 pin IC, two caps, and one resistor might be all that you need. See National's "Special Purpose Linear Devices" Databook for full details. >-- >mcorbin@oucsace.cs.ohiou.edu +-----+---\ +-----+ >CS559@ouaccvmb.bitnet | | | | -- >| ---+ >"Flat possums never DIE!" -RoADkIll +-+-+-+---/ +-----+ Domenic DeFrancesco
markz@ssc.UUCP (Mark Zenier) (09/01/90)
In article <domenic.0045@defran.UUCP>, domenic@defran.UUCP (Domenic DeFrancesco) writes: ! >In article <1702@oucsace.cs.OHIOU.EDU> ! >mcorbin@oucsace.cs.OHIOU.EDU (Max Corbin) writes: ! > ! > I have several crt boards and tubes at home and I ! > would like to use them as video monitors. ! > The problem is that they us Vertical sync, ! > Horizontal sync, and composite video inputs. ! > ! > Question -- Does anyone out there have a circuit ! > that will get these signals out of a NSTC video ! > signal? ! ! Consider using a LM1881 Video Sync Separator IC from National Semiconductor. Or get the October 1990 Radio-Electronics, which has a NTSC to RGB converter project. It uses the LM1881 and a TDA3330 decoder. markz@ssc.uucp