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Cheap composite monitor

Chuck(G)

Chuck(G)

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I had one of these in my hellbox, unused. So I hooked it to a 12VDC wall wart and the other end to the video output of an old ATSC converter box. It voiks!
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A thing that kind of sucks about a lot of these cheap composite input LCDs is they don’t like the non-interlaced output from most 70’s-80’s computers. They’ll “work”, but the output ends up with this jaggy/flickery distortion. I’ve seen this on both a 7” ATSC portable TV and on the cute little 8” 4x3 multi-input monitor (vga/hdmi/composite) I bought a few years ago for workbench stuff. I’d be impressed if it doesn’t apply to that backup monitor.

A workaround I applied to the bench monitor is using one of those sub-$10 composite->HDMI converter boxes instead of the native composite input on the LCD. People moan about the quality, or lack thereof, of those converter boxes, but they’re sold specifically with video game console conversion in mind and apparently someone in the production chain noticed that most of those did 240P and tweaked the boxes accordingly.
 
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Anyone tried driving these little things from an Orange Pi Zero? It has a video output available. I've got a few of the things kicking around.
 
I use one for when I repair consoles. Mines 4" or so. Dont really notice the shifting since the screen is so small. Very handy to have in the repair station.
 
Back in the day I had my ZX81 hooked to a 12” TV that is long gone. Thinking of doing the composite mod and buying one of these. Would be fun to see that Ready prompt again.
 
I have combo TV-monitor from late 00s Phillips 231T that used to be my main driver. Nice screen to hang on to due to all the inputs (analogue tuner too) and integrated speakers but it's 16:9 and a bit too large for "period correctness".
 
I have one of those 4.3" backup-camera LCDs and it seems to be really picky about sync. The 7" seems to be a whole different product.

A lot of sources (Sega Genesis and anything TMS99xx-based) make it roll constantly and obviously then also can't get colour. Newer stuff is no problem: an Xbox or WebTV will achieve perfect sync. There seems to be very limited room for adjustment and no obvious way to override it inside the "set." I'm not sure what the difference is between the older and newer composite signals, but I guess I could scope it and see if it's levels. It's a bit of a shame as the 4.3" is the perfect size to make into some kind of bootleg portable computer.
 
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seat safety switch said:
Newer stuff is no problem: an Xbox or WebTV will achieve perfect sync. There seems to be very limited room for adjustment and no obvious way to override it inside the "set." I'm not sure what the difference is between the older and newer composite signals, but I guess I could scope it and see if it's levels
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An Xbox or WebTV is outputting NTSC standard 480i@30hz interlaced. Most 8 and 16 bit video game consoles and computers output a not-according-to-Hoyle progressive scan. Analog CRT TVs are usually cool with this but anything that digitizes NTSC video, well, your mileage is going to vary. A lot.
 
I had Wii connected to various new panel TVs and it didn't matter. 60Hz.
 
Wii is also interlaced. (It also supports 480p progressive, but only over component cables.) The last major console I can think of that made much use of progressive scan ntsc was the PlayStation 1. Also even within the “240p” genre you’ll find significant variation in details of the source signal, including big things like how many lines it uses. (interlaced ntsc is 525 lines, or 262.5 lines per field, but various old computers have gotten away with anywhere from 260 to 264 lines per progressive field, and they also commit various crimes against the vsync pulse which CRT televisions from the mid-1960’s to the 2000s are usually fine with but are technically well outside the specifications.)

Also note that a lot of “real” LCD TVs, high end ones especially, are fine with progressive NTSC, or at least handle it much more gracefully than the dirt cheap small panels. I would guess that’s because all the small panels are tested with is camera output while the makers of high-end products are actually aware of/care about the game console use case.
 
How well NTSC input is handled can also vary with the type of panel, even for similar displays from the same manufacturer. For example, my Eyoyo 1024x768 display does an absolutely terrible looking job on upscaling 240p; a very similar Eyoyo 1280x800 display from the same line does a much better job on 240p. (Had I known this before purchase; I would certainly have bought the 1280x800 one.)
 
Eudimorphodon said:
An Xbox or WebTV is outputting NTSC standard 480i@30hz interlaced. Most 8 and 16 bit video game consoles and computers output a not-according-to-Hoyle progressive scan. Analog CRT TVs are usually cool with this but anything that digitizes NTSC video, well, your mileage is going to vary. A lot.
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The original XBOX can do 720P on many games and a few at 1080i from what I recall, 480P being the lowest resolution.

A stand alone 800x400 screen might be useful for a microscope with analog output for workbench use.
 
Unknown_K said:
The original XBOX can do 720P on many games and a few at 1080i from what I recall, 480P being the lowest resolution
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Out of the box with no optional accessories it did plain composite 480i. To do 480P or higher required a component cable. (Or, later, an analog to HDMI adapter that emulates the component cable.) The distinction I was making is that the XBox‘s 15kHz output is always interlaced, it doesn’t have a progressive 240P mode. (The contemporary PlayStation 2 could still output 240p, at least in PS1 emulation mode.)
 
Eudimorphodon said:
8” (200-ish mm) screen? You might have the same one I do.
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Yup, that's the one: Eyoyo S801C. I had thought that all Eyoyo monitors just had really crap upscalers from 15.7 kHz CVBS until I tried out a friend's 1280x720 (not x800, I mistyped above) ~8" Eyoyo and it looked way better. So I'm pretty disappointed, but don't have the money to replace mine.
 
The 5" PSOne or clone displays shipped with the smaller version of the Playstation 1 are pretty excellent. Unfortunately they're pretty expensive these days. Back in the 2006-2012 era, we were using them to make portable Nintendos and such.

We also used the generic 3.5" "backup camera display" LCDs from ebay, but many of them could not properly take the "240p" signal...

I have a device that will turn a Gameboy Advance into a TV, and it has a composite input. I brought it to a LAN party a couple years ago and we played a round of 8-player super smash bros on it for the giggles.
 
cjs said:
Yup, that's the one: Eyoyo S801C. I had thought that all Eyoyo monitors just had really crap upscalers from 15.7 kHz CVBS until I tried out a friend's 1280x720 (not x800, I mistyped above) ~8" Eyoyo and it looked way better. So I'm pretty disappointed, but don't have the money to replace mine.
Click to expand...

I guess my monitor is labeled NEEWER as the brand, not Eyoyo. But the cases are practically identical so I'm sure it's the same guts.

FWIW, I've had pretty good luck with these dirt cheap composite HDMI converters and 240P input. The main monitor I use with my TRS-80 Model I is a 17" 1280x1024 NEC monitor with one of these rigged to the DVI port in 720P mode. (1080P is out of frequency range for this monitor.) The contrast is iffy because, well, the TRS-80's output is trash, but the resolution is acceptable for the TRS-80's 64 column text output. With a cleaner signal they're... okay, for 80 column, as long as there's no colorburst. (This photo's from my homebrew video dingus that's driving the monitor straight off the TTL output from the shift register via a couple resistors, doesn't even have a proper output transistor. The fact that this is cleaner with better contrast than the TRS-80 Model I is pretty damning, really.)

hdmi_converter.jpg

I guess it should be noted that I picked this (very nice) DVI-equipped 17" 4x3 NEC monitor off a curb. (The same neighbor was getting rid of two 19"-ish 16x9 monitors as well... which I left.) A free monitor plus a $7 HDMI converter that does a "reasonable" job pretending to be a monitor suitable for 1970's-vintage gear is a pretty nice deal, even if it has its limitations.
 
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