electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
 Forum index » DIY Hardware and Software » Video synthesis and manipulation
CMP-DIV Video Effecter
Post new topic   Reply to topic
Page 1 of 1 [22 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Author Message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Fri Jun 22, 2012 3:40 am    Post subject: CMP-DIV Video Effecter Reply with quote  Mark this post and the followings unread

This post was originally stuff from another thread, and now that there's this subforum, it was thought better to put it in its own thread.

I made a video effects box which perhaps only slightly qualifies as doing synthesis, and it deals with sync in a rather simple manner. No sync generator.

Basically, it splits a composite video signal, slices it up using an LM339 comparator which clocks a 4040 divider (that's where the CMP - DIV of the title comes from), then adds a few of the divisions back to the original signal. Since the original signal is still there, the sync is preserved. Limited, but some fun stuff for such a dumb circuit.

It's also known as the Vidiffektor: http://www3.bell.net/james.schid/schidlowsky_esb.html#vidiffektor . There be a link to a demo video that shows pretty much what it does.

My friend who actually came up with the circuit had originally conceived it for audio, but then we wondered what it might do with video. We each took it in slightly different directions, but the core idea remains.

Warning: Use at your own risk. I cannot guarantee that this won't break equipment this is connected to. In certain cases, this can add a DC offset to the output signal, so it ends up between 1V and 2V. It is beyond my electronics knowledge to know if this is bad or not.

James.

P.S. I used this circuit to produce my avatar-self-portrait... those wavy lines are classic CMP-DIV effects.


CMP-DIV Video Effecter schematic.jpg
 Description:
 Filesize:  131.27 KB
 Viewed:  209 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

CMP-DIV Video Effecter schematic.jpg


Back to top
View user's profile Send private message Visit poster's website
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Tue Jul 31, 2012 1:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi RingMad

thank you so much for sharing this

I was looking for some video projects, because audio isn't really my thing

but my knowledge is very limited so far, so it's not easy, video is harder Sad

question: do you think this would work on PAL?

thanks again
Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Wed Aug 01, 2012 4:30 am    Post subject: Reply with quote  Mark this post and the followings unread

jjplano wrote:
question: do you think this would work on PAL?

I have no way to test it, but I don't see any reason why it would not work on PAL. Since the input and output is composite video, then that should be relative to whichever system it's used on.
It's pretty easy to build, so you could try it! If you do, please report your findings here.

James.
Back to top
View user's profile Send private message Visit poster's website
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Thu Aug 02, 2012 4:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi James

well, I got the components I didn't have and I build it and... it doesn't work Sad

I don't know, as I said, I don't have much practice in all this, but this is a pretty easy circuit, so I checked eveything three times and everything seems to be in order

do you know if someone has build it based on you schematics?

perhapps I can send you a couple of pictures of my bredboard

I was really looking forward to this, I have never build any circuits for video processing

thanks

edit:

this is my breadboard, look


vidiffektor-breadboard.jpg
 Description:
 Filesize:  263.71 KB
 Viewed:  140 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

vidiffektor-breadboard.jpg


Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Fri Aug 03, 2012 3:17 am    Post subject: Reply with quote  Mark this post and the followings unread

jjplano wrote:
well, I got the components I didn't have and I build it and... it doesn't work Sad


Sorry to hear that. I know of no-one else who built this. I'll examine your breadboard after work, but could you tell me what happens? Do you see anything at all?
With the "raw level" pot at 0 ohms or bypassed, even with the circuit powered off, you should see your original input signal, since if you look at the circuit, it would go straight through.

James.
Back to top
View user's profile Send private message Visit poster's website
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Fri Aug 03, 2012 8:29 am    Post subject: Reply with quote  Mark this post and the followings unread

I have image, and with the "raw" pot I can kill it

"threshold" pots doesn't do nothing at all

the pots coming out from the 4040 does affect a little the output signal (when the "raw" allows it to pass through), but there is close to no change, and it seems to be more like a "threshold" o desaturation kind of effect rather than another thing. no wavy lines here

perhapps I connected things the wrong way

thanks

Javier
Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Fri Aug 03, 2012 12:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK, I checked against your breadboard image and it looks like you connected the circuit correctly.

Now, when testing, keep the raw level at max, i.e. 0 ohms, so as to not choke the sync. If you choke it too much, then the image will loose sync. (It's just that I found one can get interesting effects by playing with this (very gently), once one has found the right threshold level).

I guess I should have explained better about the threshold, because it's the most important and difficult part. To start, leave the 1K fine tuning in the middle of its range. Now, slowly sweep the coarse threshold pot, watching your screen carefully. You might easily pass by the right spot. It might just be a quick flicker on your screen. If you see something like that, make very small movements back and forth near to where it flickered and try to find the sweet spot, then use the fine tuning pot to better pinpoint it.

I looked at the signal diagrams for PAL and it's quite similar to NTSC in its overall range, but perhaps with a small offset. I don't really know how that all works, but perhaps for PAL, a larger pot is needed in order to find the sweet spot. Try 100K instead of 50K... but turn it even slower, because the higher the value of the pot, the less precision there is.

Also note that different input signals may have different threshold settings. e.g. from a VCR or a camera, or a DVD player. One always has to adjust it to find the good level.

I'm sorry it didn't work right away for you... right now you are the PAL pioneer... exploring where no-one has!

James.
Back to top
View user's profile Send private message Visit poster's website
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Sun Aug 05, 2012 2:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

ok, I finally got time to test this the proper amount of time (and with the proper equipment)

and it works Smile

you should have put instructions since the beginning hahaha

couple of things were a little loose on the breadboard

the first 5K pot doesn't do anything here, so I'm gonna try put it in another Q of the 4040

thank you so much James, hope you try to come up with another simple but cool project like this one

all the best
Back to top
View user's profile Send private message
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Sun Aug 05, 2012 5:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

I just wanna ask you something

it's possible that you can replace the 5k pots coming out of the 4040 for 1k or even less value?

I note image distortion/change in the really lower end of the turn, really close to 0 ohms

you too?

thanks again
Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Mon Aug 06, 2012 6:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Glad you got it working, Javier! So it is confirmed that this circuit does indeed work for PAL as well as NTSC. Good to know.

jjplano wrote:
it's possible that you can replace the 5k pots coming out of the 4040 for 1k or even less value?

I note image distortion/change in the really lower end of the turn, really close to 0 ohms

For the different kinds of video sources I tried (VCR, camera), I found that 5K was a good range for me. If you feel that 1K is better for you, go ahead and use that.

Another tricky thing is that the setting of one pot can affect the settings of the others. For example, if one pot is all the way "up", then maybe another pot will have little effect, but if the pot is halfway, then the other pot might begin to have an effect. I don't really understand it... I think it has to do with the resulting overall level vs the sync. Not enough and you lose it, too much and maybe it distorts. It's a dumb circuit, but interesting things can be found... one has to explore.

James.
Back to top
View user's profile Send private message Visit poster's website
JingleJoe



Joined: Nov 10, 2011
Posts: 876
Location: Lancashire, England
Audio files: 14

PostPosted: Fri Aug 10, 2012 1:23 pm    Post subject: Reply with quote  Mark this post and the followings unread

RingMad wrote:

Another tricky thing is that the setting of one pot can affect the settings of the others. For example, if one pot is all the way "up", then maybe another pot will have little effect, but if the pot is halfway, then the other pot might begin to have an effect. I don't really understand it... I think it has to do with the resulting overall level vs the sync.

May I just chime in here and say it may have more to do with your mixing methods for the 4040 outputs and raw signal.
I can see one or two scenarios where things could be shorted out by the pots.
Give me a shout if you want my modification ideas.

_________________
As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"


Green Dungeon Alchemist Laboratories
Back to top
View user's profile Send private message
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Fri Aug 10, 2012 4:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi JingleJoe

I still have the original design by RingMad on a breadboard

so, if you want, point out your modifications, because it's easy for my to test them out, no problem
Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Sat Aug 11, 2012 3:41 am    Post subject: Reply with quote  Mark this post and the followings unread

JJ: I've already built 2 boxes with this circuit, but sure, I wouldn't mind hearing your mod ideas... admittedly, it's a pretty rough circuit. Heck, I think one is supposed to ground the unused comparators or something too.

My friend who came up with this circuit used a summing amp at the end, but I had observed it made no difference, so I didn't bother.

James
Back to top
View user's profile Send private message Visit poster's website
JingleJoe



Joined: Nov 10, 2011
Posts: 876
Location: Lancashire, England
Audio files: 14

PostPosted: Sat Aug 11, 2012 6:51 am    Post subject: Reply with quote  Mark this post and the followings unread

This will definately need testing; if you would be so kind Mr jjplano, that would be helpful, but no dire rush or anything Smile
This new arrangement should allow greater functionality and stop the controls interfering with each other.

I would advise a non-inverting amplifier at the end with a gain of about 4 (I think) to bring things back up to the level they were originally. However that will need testing/experimenting with, I don't know what kind of voltage the video input is expecting.


VIDEO EFFECTER UNTESTED MODIFICATIONS.png
 Description:
 Filesize:  47.87 KB
 Viewed:  121 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

VIDEO EFFECTER UNTESTED MODIFICATIONS.png



_________________
As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"


Green Dungeon Alchemist Laboratories
Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Sun Aug 12, 2012 4:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the mods/advice JingleJoe... if I have a moment sometime to try them out, I will.

JingleJoe wrote:
I don't know what kind of voltage the video input is expecting.

Although technically a video signal can be any amplitude, I've measured NTSC composite video signals as 1 V p-p about. There's a special relative unit used to accommodate that, but in this case it would work out to ranging from -286 mV to +714 mV.

I've measured the signal coming out of my Vidiffektor box and it goes from about +1 V to +2 V, so still maintains 1 V p-p but with a 1 V DC offset up.

James.
Back to top
View user's profile Send private message Visit poster's website
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Fri Aug 17, 2012 8:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

sorry for the delay on my answer, I was swamped with stuff

JingleJoe, I have the new circuit with your modifications, and I have no image at all

if you want to try something different, please let me know

but please do it the following couple of days, 'couse I want to turn this into a device the next week

cheers
Back to top
View user's profile Send private message
brock



Joined: May 26, 2011
Posts: 89
Location: Canada

PostPosted: Sun Aug 19, 2012 10:49 am    Post subject: Reply with quote  Mark this post and the followings unread

jj,

I've tried to figure out what the original circuit actually does and my best guess is it works as a phase lag circuit by messing with the output impedance, and it can also impose a small level shift depending on the pot configuration on the 4040 and the 339 output level.

Joe's modified circuit cannot work as the video signal source impedance is 100k driving a load of 75 ohms, so the video out will be 750 uV at most. The variable 1k max pot in the original circuit is a huge series resistance for a video signal to see and I'd guess the circuit works best with it set to 250 ohms or less. RingMad mentioned the comparator threshold setting is critical and I'd agree (without having built the thing of course). The threshold must be set in the video signal and probably above the colour burst level where it could screw up the black level clamping which, depending on your tv, could result in no output.

Good luck with this, Brock
Back to top
View user's profile Send private message
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Sun Aug 19, 2012 1:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi brock

I was just thinking that the no image has something to do with the high values of the resistances JingleJoe added

so I'm going back to the original circuit

as I said, very little electronic knowledge on my part, sadly

thanks
Back to top
View user's profile Send private message
brock



Joined: May 26, 2011
Posts: 89
Location: Canada

PostPosted: Sun Aug 19, 2012 1:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

jjplano wrote:

as I said, very little electronic knowledge on my part, sadly


None of us start out with any knowledge, we gain it as we go along, and there's no better way to gain it than by trying things out...
Back to top
View user's profile Send private message
JingleJoe



Joined: Nov 10, 2011
Posts: 876
Location: Lancashire, England
Audio files: 14

PostPosted: Mon Sep 03, 2012 4:23 am    Post subject: Reply with quote  Mark this post and the followings unread

jjplano wrote:

so I'm going back to the original circuit

as I said, very little electronic knowledge on my part, sadly

thanks

Subsequently I would advise using my circuit with a voltage follower on the end. I thought the high resistors might cause problems however I didn't know what sort of input impedance we were talking about, thankyou for clearing that up Brock Smile
Any problems with impedance in my altered circuit could be overcome by adding a voltage follower to the output, a simple op amp buffer. It may need a resistor on the output (of about 250 ohms as brock suggests) However one may also need to check the max power/current output on the datasheet of the op amp used but most typical high speed op amps should be fine.

_________________
As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"


Green Dungeon Alchemist Laboratories
Back to top
View user's profile Send private message
jjplano



Joined: Jul 31, 2012
Posts: 9
Location: Buenos Aires, Argentina

PostPosted: Mon Sep 03, 2012 8:33 am    Post subject: Reply with quote  Mark this post and the followings unread

those are tips for the next guy who tries it Wink

finished project

Posted Image, might have been reduced in size. Click Image to view fullscreen.


divisor.jpg
 Description:
 Filesize:  386.84 KB
 Viewed:  79 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

divisor.jpg


Back to top
View user's profile Send private message
RingMad



Joined: Jan 15, 2011
Posts: 214
Location: Montreal, Canada
Audio files: 2

PostPosted: Mon Sep 03, 2012 2:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice work Javier! Thanks for reporting your success in building it. Have fun!

James.
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic
Page 1 of 1 [22 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Video synthesis and manipulation
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
mps board

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use