2 inch video monitor - Page 1
Forum section: electronics / projects

author: GK
author_rank: Super Contributor
timestamp: March 01, 2014, 09:35:18 am
content: It was a really nice sunny day today, so I decided to confine myself to the shed and build this. I picked up a number of "new old stock" 2AP1A, 2" cathode ray tubes a while ago and I've been itching to do something with them. This is my best attempt at a composite video monitor using bits that I could rummage from by junk box(es).I'm using the specified maximum rated acceleration potential of 1kV for the 2AP1A. HT comes from a little universal hybrid linear/switching, variable-output PSU (the green PCB) that I originally designed for powering photo multiplier tubes, which had to be modified a little for this application.The cathode is tied to a fixed potential and grid modulation is used. From a sample-and-hold type DC restorer the video amplification path is directly coupled to the CRT grid. Being a monochrome display, the chrominance component is separated (with an old passive hybrid/thick film Sony "Y/C module") from the luminance prior to DC restoration and amplification. All this results in the best possible quality picture.Don't have the time to draw out the schematic right now. I designed the thing as I went along and 90% the schematic hasn't been scribbled down.Vertical and Horizontal raster deflection is provided by a pair of MJE340 long-tail pair amplifiers on a supply of +300V, delivering push-pull deflection voltages to the respective deflection plate pairs.That's Mark Evans on the screen, assembling a Rover V8 - from "A 4WD is Born".

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 01, 2014, 10:03:26 am
content: Awesome!Stuff like this has to be worth more than a gazillion lame Hackaday posts where someone connected an Arduino to something, or left a breadboard in a supposedly "finished" project

author: Psi
author_rank: Super Contributor
timestamp: March 01, 2014, 10:38:54 am
content: Seriously, that's amazing for a days work,Actually that would still be amazing for a weeks work

author: GK
author_rank: Super Contributor
timestamp: March 01, 2014, 11:30:33 pm
content: LOL, glad y'all like it.I've done quite a bit of video processing and have repaired and studied a lot of old oscilloscopes (a bit of a fetish of mine) so I pretty much new how to tackle the design beforehand.I'll sit down and scribble down the schematic maybe later this afternoon.

author: w2aew
author_rank: Super Contributor
timestamp: March 01, 2014, 11:49:03 pm
content: Quote from: GK on March 01, 2014, 11:30:33 pmYes, looks great! Much cleaner and crisper video than my simple NTSC to Scope converter circuit (used to make my avatar and a few of my videos). Looking forward to the schematic. Nice manhattan construction too.

author: GK
author_rank: Super Contributor
timestamp: March 02, 2014, 02:25:19 am
content: Quote from: w2aew on March 01, 2014, 11:49:03 pmYou will notice some similarity in the deflection circuitryFor the best quality monochrome picture you really need to filter out the chroma component and DC restoration of the video signal helps a lot. Without the latter the black level does not remain at a fixed level, but varies up and down along with the average intensity of the display.I don't have the schematic for the HT regulated supply module immediately at hand, as that was originally designed at work.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 02, 2014, 02:32:05 am
content: Nice!I made one quite some time ago, with a magnetic deflection CRT... should pull it out again some time and play. Although without any NTSC floating around anymore, there isn't much to display on the thing...http://youtu.be/9-y8fXgMx3wThink I later took a picture of a reasonable raster, though I didn't have enough voltage to get full width or brightness.Tim

author: w2aew
author_rank: Super Contributor
timestamp: March 02, 2014, 03:22:17 am
content: Quote from: GK on March 02, 2014, 02:25:19 amNice. I like the DC restoration circuit with the S/H.

author: Rigby
author_rank: Super Contributor
timestamp: March 02, 2014, 05:05:09 am
content: cripes, that is awesome.

author: GK
author_rank: Super Contributor
timestamp: March 02, 2014, 05:39:59 am
content: Quote from: w2aew on March 02, 2014, 03:22:17 amThe implementation is mine but the concept is an old one.

author: GK
author_rank: Super Contributor
timestamp: March 02, 2014, 05:43:14 am
content: Quote from: T3sl4co1l on March 02, 2014, 02:32:05 amThe plan is to build a refined/expanded version of this into a 2U rack case for a transmitting rack, to connect to a dedicated receiver and thus act as a "side tone" monitor for ATV transmission.

author: pickle9000
author_rank: Super Contributor
timestamp: March 02, 2014, 05:53:52 am
content: Just one more awesome!

author: marshallh
author_rank: Unknown
timestamp: March 02, 2014, 06:10:43 am
content: Well, I'm just going to hang it up now. I'll never be this awesome

author: vk6zgo
author_rank: Super Contributor
timestamp: March 02, 2014, 07:24:54 am
content: Reminds me a bit of the 5" TV I made years ago,using a 5BP1.It was already years after such things were worth making,some of the valves(tubes) in the original design weren't available,so I made (not so appropriate) substitutions.It worked,on one occasion--I saw the end of a movie,but it still had a lot to do to finish it off.I lost interest,& never did that work,so it ended up being pulled apart for bits.

author: megajocke
author_rank: Regular Contributor
timestamp: March 02, 2014, 10:16:06 pm
content: Cool!

author: Fraser
author_rank: Super Contributor
timestamp: March 02, 2014, 10:34:08 pm
content: Thanks for showing just how cool CRT's are. I have seen posts from some on this forum who want to see such technology disappear into history........ not me, I grew up being fascinated with the warm glow of thermionic valves and CRT's. I have many small CRT's sitting in my garage awaiting projects or use in repairs. LCD has its place but, to me, it is 'dead' and whereas a CRT has 'life' in it

author: IanJ
author_rank: Unknown
timestamp: March 02, 2014, 11:39:32 pm
content: Message to Mark Evans sent.........I'm guessing he'll get a kick from this.Ian.

author: GK
author_rank: Super Contributor
timestamp: March 03, 2014, 08:32:36 am
content: Gee wiz, small world!I brought my DVD player into the shed to use as the signal source for testing andA 4x4 is bornjust happened to be the disc that was in it. Quite enjoyed the few episodes of theIs Bornseries that I have seen so far, though that Landrover should really have been given a Chevy V8, with actual grunt.This thread has received an impressive number of views so far, given its age. I wonder if people searching for "Mark Evans" or related are being directed here?EDIT:Blimey! ".....and 55 Guests are viewing this topic". Other threads at a quick glance have one, two or three..............

author: dexters_lab
author_rank: Unknown
timestamp: March 03, 2014, 04:28:32 pm
content: nice project!you could make a internet connected thing so you could pop-up new videos from your YouTube subscriptions onto it

author: GK
author_rank: Super Contributor
timestamp: March 16, 2015, 11:46:41 pm
content: Finally got this thing written up a little more comprehensively:http://www.glensstuff.com/vidmonproto/vidmonproto.htmCurrently working on the rack-mount case, general-purpose video monitor implementation.

author: Stonent
author_rank: Super Contributor
timestamp: March 17, 2015, 04:13:11 am
content: Would you be able to trim the circuit down with just the Luma component from a S-Video cable?

author: GK
author_rank: Super Contributor
timestamp: March 17, 2015, 04:24:27 am
content: Sure, there'd be no chrominance component to filter out then.

author: tautech
author_rank: Super Contributor
timestamp: March 17, 2015, 04:36:47 am
content: Any plans to use it with your Chaos circuits?

author: GK
author_rank: Super Contributor
timestamp: March 17, 2015, 05:02:23 am
content: Not sure how that would work as the chaos circuits don't produce composite video!However I did actually film a video of an animated (rotated on axis) chaotic attractor displayed on that prototype video monitor. Basically a C.R.T. display displayed on a C.R.T. display. I did this by displaying the attractor on my Tek. 545B oscilloscope and putting a CCD camera module in front of the screen. However the video quality from the CCD camera wasn't great, and to anyone viewing the video that could be interpreted instead as the prototype video monitor itself having poor image quality, so in the end I didn't bother uploading this video for illustrative purposes.