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 Forum index » How-tos » Visualizations - VJ etc
Visualist
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ARieu



Joined: Dec 13, 2010
Posts: 3
Location: Maastricht The Netherlands

PostPosted: Tue Mar 01, 2011 4:12 am    Post subject: Visualist
Subject description: A 'make it yourself instrument' for the VJ/artist
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Not as small as the InstantVJ but full potential; the VISUALIST.

http://www.youtube.com/watch?v=99j3V9t26pY

For the VJ/electronics a nice d.i.y. project with
a building guide to it, enjoy.
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egw



Joined: Feb 01, 2003
Posts: 1511
Location: Asheville NC
G2 patch files: 8

PostPosted: Tue Mar 01, 2011 7:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Love it! Anyone interested in building me one of these?
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PHOBoS



Joined: Jan 14, 2010
Posts: 1751
Location: Moon Base
Audio files: 347

PostPosted: Thu Mar 03, 2011 12:16 pm    Post subject: Re: Visualist
Subject description: A 'make it yourself instrument' for the VJ/artist
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ARieu wrote:
Not as small as the InstantVJ but full potential; the VISUALIST.

http://www.youtube.com/watch?v=99j3V9t26pY

For the VJ/electronics a nice d.i.y. project with
a building guide to it, enjoy.

funny, just got the link a couple of days ago from a friend (Bart Wink)
I do plan on building one or using this as a start. The MC1377 is a bit hard
to find but I managed to find one. (I think I'll get it in the mail tomorrow).
It could take a while before I actually start experimenting with it as i'm
already working on numerous things, but I shalll use this thread for updates
if i do.

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PHOBoS



Joined: Jan 14, 2010
Posts: 1751
Location: Moon Base
Audio files: 347

PostPosted: Sun Mar 27, 2011 7:03 am    Post subject: Reply with quote  Mark this post and the followings unread

I've started experimenting with this circuit. I first made a little board with the MC1377 and surrounding components, which has RGB and sync inputs and composite video out. This saves me some breadboarding space and eliminates some possible errors and noise. I discarded the 4052's and control circuit for now, which i'll probably gonna do different anyway.

At first I hardly got any image, sometimes I could recognize something but it was definitely not what it was supposed to be. I also had a hard time getting the sync setting right, I had to turn the 250k trimpot (i'm using a 25 multiturn) almost to zero resistance for it to work. Sad Since I also had a LM1881 sync separator I decided to use that one. This got rid of the sync problem but it still didn't work well. On closer inspection of my MC1377 board I noticed that I had connected the video output (that is the cap that's in series with it) to the base of the transistor instead of the emitter. After correcting this the result was much better. Smile (I'm using BC547B transistors btw).

Now I actually could recognize the video and could change the colors. But the overall image had a lot of black in it. Also the 2K5 pot that's connected to PIN 5 of the MC1458 hardly had any effect. I tried swapping the 2 internal opamps to make sure the chip was ok but I got the same results. So I started to do some calculation and and according to those I should be able to set a voltage level with the pot between ±1V and 2.3V. But I only measured a level going from 2V to 2.2V. I tried connecting the input (PIN 5) to GND and still got a minimum voltage of 2V.

I tried a different opamp (LM358) to see if I could get it lower and that worked much better. It can even go below 1V and gives much more ccontrol with the 2K5 pot. This solved the problem of a large portion of the image being black. I don't know why it doesn't work for me with the MC1458, maybe it has something to do with using a LM1881 for the sync but that still doesn't change the minimum ouput voltage of the opamp. Rolling Eyes

I've changed the values around the 2 2k5 pots and given them each there own set connected to +12V and GND. this gives me a much wider range and I now I can also get a hard contrasted B&W image some weird gray effects and completely different colors (brown, orange, purple, dark green and others). I'm planning on adding CV inputs for these controls that will convert a 0-10V signal to the appropriate levels. I'll probably do the same thing with the RGB levels. Of course this will also still give me the option to use an audio signal. Laughing

For the 4052 section I'm thinking of using a sseparate mux for R, G, and B each with switches to select the input color. (Since the 4052 is a double mux I might use the other half for a RGB LED). This gives the possibility of using all options including having more channels set to the same color. I'll also add some sort of automation to it aswell (maybe with a PIC?) and probably external inputs too.

Something I've noticed that I don't like is that the 680 ohm pull-up resistors connected to the 4532 get pretty warm or I should say hot since I can't keep my finger on them for too long. The strange thing is that if I connect a 680 ohm resistor directly between +12V and GND it doesn't get so warm at all. Maybe this has something to with the high frequencies. So I'm gonna try increasing the resistance of these to see if that helps.

Overall I am getting some nice results now, And I'm not even using any automatic ccontrols yet Very Happy

(btw I don't know if I connected the 10.7MHz filter correctly. I used the print layout as an example and the video looks as i would expect but turning the filter doesn't have any effect at all)

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ARieu



Joined: Dec 13, 2010
Posts: 3
Location: Maastricht The Netherlands

PostPosted: Sun Mar 27, 2011 2:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

He PHOBoS
You gonna do it different anyway and I think "that is how it is ment to be".
Cutting out modules (4052) ,using other parts (LM1881), making other control inputs; that's open hardware. Here is no difference in designing hard-or software.
On my oscilloscope I saw that turning the core of the 10.7Mhz filter doesn't has any effect on the suppressed colorburst . As said; not perfect but sufficient.
The main job you did was the comparator. Having a wide luminance range and sharp clean edges gives more visual quality to this circuit. Find a better comparator than the LM339. I can't wait to see your the first video results of your 'mod'.
Glad to hear that you got results and you are the first to tell us about that. Bravo!!!
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