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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 19, 2009 1:03 am Post subject:
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Okay, next I've tried adding a third pot with each side connected to +12v and to -12v, the output of which is sent to the 4053 as the black level pedistal (instead of to ground... akin to the blanking/pedistal board in the Sandin.) This is definitely working! Still a long way to go with tweaking/optimizing the control ranges -- but now I can get a solid color field with no input (by properly setting the pedistal and offset knobs) -- which tells me that the black level/composite blanking must be working. |
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dar303
Joined: Jul 15, 2007 Posts: 97 Location: Sweden
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Posted: Mon Jan 19, 2009 6:53 am Post subject:
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Very cool!
Do you have any pictures for us? ) |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 19, 2009 12:41 pm Post subject:
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I'll try to get some pictures up today.
In the meantime, here's that Supernova documentation. This documentation is copyright by Stephen Jones who insists it not be used for anything other than personal research, and not for commercial endeavors.
I pretty much cloned the CD4053/LM339 section of the blanking circuitry exactly, except that the black level inputs are going to the pedistal level instead of ground. I really need to find a good op-amp solution to use throughout these experiments.
Any ideas on something available from Mouser that would work as an EL2444 substitute?
EDIT -- I've been asked to not distribute the schematics just yet, so I've removed the PDFs from this post. Hopefully I'll be able to repost them soon once I ask for permission in this specific context. Last edited by creatorlars on Tue Jan 20, 2009 8:22 am; edited 2 times in total |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 19, 2009 12:41 pm Post subject:
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One more. |
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BOB-SNARE
Joined: Sep 26, 2008 Posts: 30 Location: Australia
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Posted: Mon Jan 19, 2009 5:24 pm Post subject:
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creatorlars wrote: |
In the meantime, here's that Supernova documentation.
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Cool Thanks!
Quote: |
I pretty much cloned the CD4053/LM339 section of the blanking circuitry exactly, except that the black level inputs are going to the pedistal level instead of ground. I really need to find a good op-amp solution to use throughout these experiments.
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Is the output of the MFOS +/-10V?
Do you attenuate the signal to 1Vpp before (TL072) buffering?
If you're only using VCO generated signals TL07x is OK as a buffer. The edge rate is a little slow for a camera, and will only show up as softer edges.
My problem might be that the Y-plus board has 470R impedance to GND on the RGB inputs and I've been using that with 2K in series to attenuate 5V signals to 1Vpp.
Are you using the 75R output resistor into the Y-plus board?
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Any ideas on something available from Mouser that would work as an EL2444 substitute? |
Available at Digikey, you could try AD828 voltage feedback dual op-amp. +/-15V, DIP8 package. I haven't used this, but on specs it looks suitable. |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Mon Jan 19, 2009 5:35 pm Post subject:
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Quote: | Is the output of the MFOS +/-10V? |
I believe so.
Quote: | Do you attenuate the signal to 1Vpp before (TL072) buffering? |
Yes, but it seems like I can push it harder than that, too... I also am mixing the offset level (which is just a pot connected to negative and positive power on both ends) at the TL072 input too. I am not sure how/if this is helping me though. I'm confused on the difference (if any) between "offset" and "bias" controls. The Supernova has gain/bias knobs for each input -- but the schematics for that portion of the circuit are omitted. It appears the Sandin uses two diodes in the "bias" control -- does that look right?
Quote: | If you're only using VCO generated signals TL07x is OK as a buffer. |
That is good to know -- I figured most dual op-amps were pin compatible and I could swap it out later when I got something better. The AD828 chips look good -- I wish they weren't so expensive. I have a ton of NE592s, but no real sufficient knowledge on how to use them.
Quote: | Are you using the 75R output resistor into the Y-plus board? |
No, do you think I should? Right now the CD4053 output is going directly to the Y-PLUS board's input.
Do you have suggestions on why I'm not having luck with doing the clamping to ground as per the Supernova 12's documentation? Do you think an extra buffer between the CD4053 and the Y-PLUS board is necessary? |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Tue Jan 20, 2009 9:29 am Post subject:
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I apologize for having to remove the Supernova schematics. Hopefully I can repost them soon.
In the meantime, here is a rudimentary schematic (sorry, first one I've ever done) of my implementation of the circuitry between VCO output and the RGB Encoder's input. As you can see, it's a little sparse -- and there's at the very least a lot of adjustments to be made on the range of the controls.
I'm sure the "offset/bias" control could be better handled and the input buffer could probably work with just one op-amp. This is basically a clone of the CGS DC Mixer circuit (which I've had experience before and knew would probably work okay.)
But in any case, this circuit "worked" in the instances that I was able to feed a sync-locked VCO into the input, feed Composite Blanking from my NTSC Sync Generator into the Composite Blanking input, connect the output directly to the Y-PLUS board, and generate stable patterns and adjust overall color level (by changing the offset after pedistal was appropriately adjusted.)
If anyone here more experienced than I am could take a look and tell me what I'm doing wrong, I'd appreciate it!
The op-amp actually used was a TL072, and the IC power connections/.1uf decoupling caps are not shown (but were there). All three ICs were connected to +12v and -12v.
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lars_rgb.pdf |
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BirdGuy
Joined: Mar 02, 2009 Posts: 1 Location: US
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Posted: Mon Mar 02, 2009 6:04 pm Post subject:
MC1377 Subject description: I have some MC1377s for sale cheap. |
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I have 12 MC1377s for sale cheap. They are $2.50 each plus minimal shipping costs. If you buy 4 or more I will pay for shipping.
Thanks,
Phil Cline |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Thu Mar 05, 2009 1:29 pm Post subject:
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There has been a lot of progress on this project so far, but I am waiting on a few things before posting more about it. Here's a quick video clip, courtesy of zonkout. It is just filmed off of a projector on the wall.
http://www.flickr.com/photos/zonkout/3317743079/ |
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dar303
Joined: Jul 15, 2007 Posts: 97 Location: Sweden
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Posted: Mon Mar 09, 2009 9:15 am Post subject:
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wow, nice! Good work! |
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MC1495
Joined: Mar 24, 2009 Posts: 19 Location: baltimore
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Posted: Tue Mar 24, 2009 9:10 pm Post subject:
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could i convince someone to help walk me through the process of creating and adding a sync signal to an RGB-->NTSC IC?
i'm a bit confused about that process..
thank you.. |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Tue Mar 24, 2009 11:23 pm Post subject:
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You'll need a sync generator -- you can buy one (I have one I bought off eBay) or you can code one. I am currently testing one based on the AVR coded by BOB-SNARE. Be sure to read this whole thread, there is lots of discussion on the sync issue...
Which RGB IC are you using? |
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MC1495
Joined: Mar 24, 2009 Posts: 19 Location: baltimore
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Posted: Tue Mar 24, 2009 11:44 pm Post subject:
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Looking over the thread, there was mention of the LM1882 to generate sync - and a schematic was even offered, but I don't think it materialized.. This seems to be the most ideal process for my means, but I'm very uncertain about how to proceed..
As for the chip: I'm using (well, hoping to use) an AD724... |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Tue Mar 24, 2009 11:53 pm Post subject:
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You should be able to get a basic schematic from the datasheet. The modern LM1882 replacement is the 74ACT715. The CD22402 looks like a good IC option too, but it requires an obsolete crystal. |
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spippoli
Joined: Nov 23, 2008 Posts: 19 Location: Italia_pizza_mandolino
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elgauchoandres
Joined: Feb 15, 2007 Posts: 7 Location: Barcelona
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Posted: Sat Jun 20, 2009 6:16 pm Post subject:
About the CD22402... |
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creatorlars wrote: | You should be able to get a basic schematic from the datasheet. The modern LM1882 replacement is the 74ACT715. The CD22402 looks like a good IC option too, but it requires an obsolete crystal. |
It seems that ic is not available anymore, you know a source for that chip?
Time back I wanted to build a blackburst generator or genlock module for my videosynth project and that chip was the right option but never found a supplier.
In a videosynth sync is a serious thing, how do you solve that in your project? |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Sat Jun 20, 2009 9:09 pm Post subject:
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The 74ACT715 is still being made. You can get it from DigiKey. Mouser sells an NTE replacement for the CD22402, but you'll have to come up with a clock that will work. We are currently using an AVR for sync, there will be more info on that soon. |
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elgauchoandres
Joined: Feb 15, 2007 Posts: 7 Location: Barcelona
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Posted: Sun Jun 21, 2009 4:44 pm Post subject:
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Today I stay away from old chips . Back then I used SAA1101, the only sync chip I could found, and then tried some HD4407, which came from broken cameras.
The SAA did a good job and allows me switch between PalN for standard VCR and PalB for studio machinery, and some NTSC too. And before that, I tried to build the synch generator from the descrambling book of the smart guys Graff and Sheets, but that IC was difficult to obtain in my country.
If I had to do today, I think that would also include some modern video formats (hd, uwxga, etc)
Please tell me about the circuit you're doing, I remember that Bob mentioned the AVR (in VJforum) but the author is a russian guy.
About the Supernova mentioned before, you are building one? (I'm lame, I can't grab de pdf at the time) |
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bod
Joined: Apr 28, 2009 Posts: 148 Location: Glasgow
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Posted: Fri Jul 31, 2009 4:09 am Post subject:
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good god! how did i miss this thread?
i have a bit of a soft spot for video synths too! i've been playing arround with various designs for a while, including some of Brian Mckennas circuits from his VGA synth.
i'll try and post some links to my experiments tonight, i cant access my site or youtube from work, or you can search youtube for my videos, posted by vidiotsquad.
your efforts are looking really nice creatorlars! keep it up! |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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Posted: Fri Jul 31, 2009 7:26 am Post subject:
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hey bod!
your videos look great. i'm glad you popped in!! i should have some more news/info about the video stuff i've been working on with another forum member over the past several months very soon.
did Brian McKenna actually post some schematics from the VGA synth? all i remember seeing is a block diagram -- can you post a link? |
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bod
Joined: Apr 28, 2009 Posts: 148 Location: Glasgow
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Posted: Sat Aug 01, 2009 1:15 am Post subject:
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glad you like em chief!
brian had a vidisynth forum thats long since been taken down, but there was a schematic that he had roughly drawn off his breadboard of a tv test circuit by a mexican bloke (i think) that he had addapted for VGA.
the only copy of the schematic i have is a print out which i've since drawn all over, but to be honest there were a lot of mistakes in it that i found. a good leaping off point though!
i'm just finishing off a few projects then i'm going to start work on this again, so i'll re-draw the schematics at some point for you as long as brian doesnt mind. |
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bod
Joined: Apr 28, 2009 Posts: 148 Location: Glasgow
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Posted: Sat Aug 01, 2009 3:29 am Post subject:
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glad you like em chief!
brian had a vidisynth forum thats long since been taken down, but there was a schematic that he had roughly drawn off his breadboard of a tv test circuit by a mexican bloke (i think) that he had addapted for VGA.
the only copy of the schematic i have is a print out which i've since drawn all over, but to be honest there were a lot of mistakes in it that i found. a good leaping off point though!
i'm just finishing off a few projects then i'm going to start work on this again, so i'll re-draw the schematics at some point for you as long as brian doesnt mind. |
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