Lunetta visuals

[electri-fire]

There's circuitbent SK-1's with video output.

http://www.youtube.com/watch?v=JU_SB88RXTw

The video output is connected to (I think) a chip select line at the SK-1's RAM/ROMs . Those put out 5V squarewaves. Waves are depending on sound select and keypress.

Here's a schematic.

http://www.getlofi.com/wp-content/uploads/2007/02/casio_sk-1_video_out-2.JPG

This has led me to the idea a Lunetta could be used to generate visuals, but it will take me some time to do it. You fast builders may give it a try.

[tjookum]

thanks for making that connection electri-fire.

Did a little search to find out what kind of voltages are required and how the signal works:
http://www.rickard.gunee.com/projects/video/pic/howto.php

hmmm, seems like all you have to do to get something going is limit the voltage to 1V. sweet!

[electri-fire]

[-minus-]

Oh... There's a thread here on E-M somewhere with some circuit bent TV stuff.... but I cant remember where. Has anyone tried to plug a lunetta output into a TV yet? I'd be interested to try this but don't have a TV.

[droffset]

I started reading up on how to do the proper synch signals for a TV signal but couldn't really get my head around it. I think if someone had a plain language explanation of it with maybe a basic schematic.

Alternately, maybe there's a simple video toy that can be hacked into to just make use of the signal format stuff.

[tjookum]

It says somewhere gijs uses a seperate hardware device with a time base corrector(tbc). some more info here:http://www.karlklomp.nl/inf/faq.html

It says a device with tbc will stop the picture from scrolling, very important.

Of all the cables and connectors in the house I don't have one for video , really want to try this

[tjookum]

ok got myself a cable and decided to just wing it and see if it will accept squarewaves right away. Hooked up a oscillator, added a 1n4148 and a 100k pot and measured the voltage at 0.5-0.7 volts. I was really carefull about this cause I only have 1 working tv .

And.....nothing happened, no surprises there. I think it mostly has to do with my quite modern THOMAS bargain tv, it just says no signal. I guess for this to work you would need an older model wich just displays whatever it's fed.

And then there's still the little issue about the sync function, but it seems someone has done all the hard work for us:
http://www.arduino.cc/playground/Main/TVout
There might be something out there for pic too.

[RF]

well - good try anyway, tjookum....
Thanks for the progress report.

bruce

[adambee7]

casper electronics knows a thing or two about video manglement. He got old nintendo consoles and casios. From my college days i remember playing around with a video effects mixing deck thing which used to be used at the BBC and some of the effects are similar to bent gear. Very lofi.

[kkissinger]

[tjookum]

[electri-fire]

Exhaustive list of useful videocircuits.

http://www.epanorama.net/links/videocircuits.html

[slacker]

I don't know if it's any use but the CMOS Cookbook has a circuit snippet for generating a composite video signal using a CD4066. It's supposed to be hooked up to something that generates the proper sync signals, but you might get something out of it just hooking up random signals.

If I get chance I'll try it out and see if I can get anything useful out of it.

[droffset]

[slacker]

Success

Hooked up the circuit from the CMOS Cookbook and it works. The original circuit is supposed to take a 60Hz V sync signal and a 15,750Hz H Sync signal together with a serial stream of 1s and 0s into the video input and produce a monochrome composite output. The H and V sync input had RC one shots on the inputs to generate the correct length pulses, but I couldn't get it to work with these on so I ditched them.
Happily just feeding a bunch of clock signals into the 3 inputs produces an output that my TV will display

The picture's monochrome, but it's a start. I didn't have time to get any video so a photo will have to do for now.

Obviously, if you build this, you do so at your own risk and I take no responsibility for any damage you do to your TV, your Lunetta or most importantly yourself.

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[tjookum]

thank you so much slackers, that looks great! Really great that you found the time and did the effort to get this one working

Im gonna get myself a 4066 and give it try.

[electri-fire]

Interesting, thanks Slacker.

I already had some idea the V and H sync not to be essential as video outputs of circuitbent stuff don't have that either. Apparently, as long as you have "some" Lows available, they'll somehow be interpreted as sync signals.

Considering V sync , H sync and Video can be random Lunetta signals, I wonder what is the absolute minimum amount of circuitry necessary.

V sync and H sync let through a 5V High when both are High. Else Low.

The Video signal bypasses the 1k5 resistor. So the composite video output is one of three options: Low, when In is Low, and two levels depending on the state of the Video signal.

As the level determines the brightness more level options could maybe lead to more varied visuals. Maybe instead of the 1k5 resistor use a smaller one (47 ohm?) and a potmeter, 1k or 5k.

And as we'd be varying voltage anyway, maybe an R/2R or passive resistor mixer could take in more Lunetta signals to provide more level options.

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[-minus-]

Exciting developments! I'll be watching this one with interest. After nearly 3 years without TV, I'm almost tempted to pick up an old one and try this. Best thing since TV!

[Inventor]

I too am excited by this possibility. I see a really fun and useful set of circuits emerging to address this technical hurdle and give us really cool video of our Lunettas! It's also fun to read up on the thread.

Mathe, please don't go overboard trying to get us video for em10 as I don't want to see you stressed out at the festival. We have enough to do with documentation and stuff, so chill bro!

Looking forward to future developments on this one.

Les

[electri-fire]

[Inventor]

[slacker]

Thanks for the comments, it's a fun thing to mess about with, makes an interesting little modulator for audio as well.

electri-fire thanks for redrawing the schematic, makes it easier for other people to see how it works.
Your simplified version should work, the V and H switches are just making an AND gate so any stream of pulses should work just as well. Replacing the 1k5 with different values does change the brightness level, like you suggested. As far as I can tell anything that produces voltages in the correct range with the occasional 0 volts to act as a sync should work.
Adding colour will be trickier I think.

[tjookum]

Another succes, got mine working today.

I followed the slacker schematic and with my modern tv it wouldn't recognize the signal but I could see the image changing. After switching to an older set it worked perfectly the first time, bands of monochrome goodness passing over the screen. Using some very high frequency clocks I almost got the image stationary and it worked very intuitive a little like tuning a drone.

Because I had no 1k5 and 100r I used 2 2k trimpots, at first dialed in on the same resistance wich gave nice black and white. But by increasing the resistance I got more definition and it would follow the music better and with lower resistance it started going into red and some different greys.

I shot a video where im feeding it a signals from a melodygen going through a YAVCO(probably a xor in there too). I started with the high resistance setting and somewhere halfway switched to lower resistance with some red showing through. The rainbow prism effect is due to my crappy camera and it has a lot more fine detail in real life but it shows what can be done.


Thank you guys for the inspiration and the schematic, Ive had a blast playing with this new toy all afternoon.

If I find the time Im going to try to dial down the exact frequency for the sync inputs.

[slacker]

Great video, I love how in the Lunetta world things can go from ideas to reality so quickly.
Looks like you've been able to get a much brighter image than I have, I'll have to experiment with resistor values.
I had a thought about getting colour. The colour signal is something like a 3MHz sine wave superimposed on the monochrome signal, so you might get something if you fed a fast enough clock into pin 2 instead of just connecting it to 5 volts and then AC couple or lowpass filter the output a bit.

[tjookum]