Jens, The horizontal sync requirement of this monitor (52 uS / 19.2Khz) is somewhat higher than a standard NTSC signal which is about 63 uS / 15.7 Khz.
Mark On Saturday, April 10, 2021 at 8:04:15 AM UTC-5 Jens Boos wrote: > Thank you! I did some more digging and found the service manual for the > display (Panasonic TR-60S1A, see here: > https://www.opweb.de/english/company/Panasonic/TR-60S1A) > > There is is a timing chart (see below). It looks an awful lot alike NTSC > to me, can somebody confirm? > > Best wishes > Jens > > > > > On 2021-04-10 12:28 a.m., Adrian Godwin wrote: > > It's easy enough to extract the sync signals, as you've seen. It may not > be particularly difficult to modify the TTL input to analog, or to create a > TTL level signal if you don't need a grey-scale. On many general-purpose > monitors like that they could often be built for either standard - the > microvitec Cub popular with the BBC Microcomputer had that option. > > But the critical thing is that it runs at the right speed. CRT circuits > are built around the line oscillator which generates the horizontal scan > AND the EHT voltage. It was only when multisync monitors came along that > the optimisation was split to reduce the dependency. And if the frame > frequency is wrong, you will often have problems getting a full frame scan > when you force it into sync. > > So the first thing is that you need to make sure the 8920 monitor ran at > either PAL or NTSC rates so you can choose a raspberry pi format to match. > There's a good chance it's NTSC but later monitors like the ones in the 54 > series of digital scopes were more like the IBM standards MDA and EGA (CGA > was NTSC). > > On Sat, Apr 10, 2021 at 4:28 AM jb-electronics <webm...@jb-electronics.de> > wrote: > >> Hi all, >> >> This is a bit of an off-topic question, but I hope there will be >> somebody here that can help. I have bought a new-old stock monochrome >> CRT for a HP Agilent 8920A, basically this unit here: >> https://www.ebay.com/itm/273930914548 . >> >> It looks to me that it is just a rebranded OmniVision 6" display: >> >> http://www.omnivisionusa.com/Industrial-LCD-CRT-Monitors/replacement-crt/crt-monitors/6-inch-kit-.html >> >> Now unfortunately it takes TTL video as input. But I have a composite >> source (a Raspberry Pi). How can I convert composite into TTL? I >> basically need to extract Hsync and Vsync and feed it separately to the >> unit, okay. There is an old circuit here that does just that: >> https://www.elektormagazine.com/magazine/elektor-198812/47485 >> >> But I know there are also dedicated chips, like the GS1881: >> >> https://www.mouser.com/datasheet/2/761/GS1881_GS4881_GS4981_Datasheet-769183.pdf >> >> So basically here is my question: before I dive into this any further, >> is there any chance of success? What is the optimal choice? Or is it >> quite unlikely that I will be able to convert the signals? I mean, even >> if I manage to extract Hsync and Vsync, is it likely to work? >> >> I am sorry for the naive question, but I am no expert on video signals, >> and it would be nice if anybody more experienced could chime in with a >> few words of caution/experience. >> >> Best wishes >> Jens >> >> -- >> You received this message because you are subscribed to the Google Groups >> "neonixie-l" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to neonixie-l+...@googlegroups.com. >> To view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/e0f398e8-24b1-952c-c998-0ddfbed6849e%40jb-electronics.de >> . >> > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neonixie-l+...@googlegroups.com. > > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/CALiMYrvHCiXd3QSDmEJ%2Bpe3XgUutOC_C3yLFGxeOEo2bjtEAWw%40mail.gmail.com > > <https://groups.google.com/d/msgid/neonixie-l/CALiMYrvHCiXd3QSDmEJ%2Bpe3XgUutOC_C3yLFGxeOEo2bjtEAWw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/a3fe30c7-c778-444a-a745-b6f6b1910bb1n%40googlegroups.com.
