In this experiment, i connected an audio signal to the RGB lines via a an inverter and a couple of other IC’s for some added fun, and using different combinations of connections, the audio is represented on the screen.
I wan’t really expecting much from this, in fact i didnt think it would work at all, however the results were quite impressive for such a crude circuit!
After playing arround with this, i’ve found out a few interesting things. Firstly, soldering a 15 pin D socket and mounting it to case is a pain in the ass, and secondly, if you strip the rgb content from the vga signal, you can replace it with what ever you want as long as the sync signals are intact.
This allows the monitor to be fooled into thinking the signals its being sent are from the same source as the sync and will pump out what ever you throw at it with in reason. So, with a few modifications to the circuit, i’ll be able to generate complex wave forms from the audio input to output over the RGB lines, and give the option to super impose them onto images from the original RGB inputs….
I ended up adding a couple of diodes to the sync cables as there were some issues with the monitor not being able to sync with the computer properly with some of the connections, and this seemed to solve most of the problems. There was no scientific reasoning behind using the diodes that i did, other than they were spare ones i had from before. Maybe something more specific would be better.
The whole point of this was to see how the RGB lines reacted to a raw audio input, and what connections need to be left alone, to allow stable operation of the circuit. In future experiments, i’ll know what “normal” audio reaction looks like, compared to new circuits i’m going to be playing with, and gives me a reference point to come back to.
Different audio frequencies create a line on a certain point of the screen. there are a few different combinations of effects here, and color switching controlled by activating the switches connecting the circuit to the RGB connections of the VGA output, so i can produce more than just red, green or blue images, but a few mixed colors as well. Maybe a color mixer could be incorporated into the final project… Although this thing is great fun already!!!!
I decided to house the whole thing in an old project box i had after building it on a bread board. Its a nightmare of wiring in there! Next up is to create an envelope follower circuit to see how this synth circuit reacts to control voltages, instead of a raw audio input. I’m going to try out a few different versions of the Dr. Quack circuit to see what results i get from each. More On that later.
there’s a whole lot of wiring in there!!! these hammond electricals boxes are really handy for these things, stompboxes and little noise synths, and are really sturdy too! this poor little sod ended up being used for a quick kick about in a venue after a gig as someone spilt a pint over the lighting desk and it died, but after drying out it was still alive, if a little scuffed arround the edges. it just goes to show how solid these cases are, however he-who-shall-not-be-named still bears a scars from a failed flying volley… so perhaps a little too solid for that purpose.
August 23rd, 2007 - 3:13 pm
amazing dude! i want some for my new live set!
December 17th, 2007 - 10:09 pm
http://www.art-rash.com/pixelform/video/apeiron-peras-i-comp.mov
I’m in the process of moving my site from one server to another so my data page is down but I thought you’d enjoy the video I have posted. I talked to Brian as well about the VGA synth he built and decided to experiment and came up with my own design. I’m still baffled by how he came up with the vertical banding but, again, I found something else of my own which worked out well. The video and audio are generated by feeding the outputs of the synth to the inputs using an audio mixer (the video outputs are the audio outputs so 3 ins to 3 outs but the outs are interpreted as VGA RGB and audio 1,2,3). I also have a few reverbs I threw into the loop but that’s about it. There is also some extra magic having to do with diodes feeding 4040 counters and 4066 switches to mix out the audio to different RGB outputs… really I need to post the info page again.
Pardon the poor compression quality.
December 18th, 2007 - 7:34 pm
cheers for the link mate! i’ve actually been a fan of your work for quite some time now, in fact i think we spoke in length about your audio reactive circuit for the NES console a while back when you were just prototyping it. there’s a few sites i tend to check in on every now and again to see whats new, and yours is one of them. i loved your work on the TI-99, i dont think you could squeeze much else out of that thing!
I have to say that i too am completely baffled by brians vga synth! i havent done too much work on it recently, as i’ve been side tracked by the audio synths i’ve been working on, but i’ve had some nice results from what i’ve done since this page. i’ll need to document it some time over the holidays. I started with a good scientific basis of what i wanted to do with the vga experiments, but its digressed into just random trial and error with different components and IC’s until i find something nice, then try and work out why it does what it does afterwards in the hope to understand it.
anyway, thanks for stopping by chief!
bod.
February 19th, 2008 - 8:27 am
I just wanted to say; this is some excellent work. Thanks for sharing. I really must try this out some time.
February 19th, 2008 - 9:44 pm
cheers Seb! coming from you that means a lot! I like the stuff you’re doing with the 4D systems stuff. that uVGA synth you made is cool!
February 21st, 2008 - 12:10 am
Just one last thing… i assume from reading the above, that pins 1, 2 and 3 are the only pins not normally connected to the monitor, and that it is these three pins that you are poking with strange (audio) signals? All the other pins that normally go through are connected through?
February 21st, 2008 - 9:51 pm
hi seb,
yeah its the data lines for the rgb signals that are cut and replaced with a new source, the ground lines for the RGB and everything else are intact. i built a wee break out box for myself which makes things a lot easier, and i have a schematic for a pcb i made up to do the same job. just remember to connect any pattern generation circuits to the ground lines of the vga cable.
you can pump audio straight into the data lines, but there’s a whole host of other tricks you can do with a bit of experimenting. these experiments just used audio, an inverter, a 4066 and sync signals tapped from the vga cable/breakout box in various formations to generate patterns.
i’ll dig a few things this coming week to update these pages.
February 23rd, 2008 - 8:04 am
Hey, just thought i would let you know that i have posted a video of some vga stuff based on your stuff (but controlling the data lines with an Arduino instead). Actually, it is working really well! If you feel like watching it, the url is: http://youtube.com/watch?v=HNJxHzu2NLg. Thanks again for posting! I have done some similar stuff with oscillators and composite video signal, but i’ve gotta say, using VGA… just brilliant!
February 23rd, 2008 - 1:23 pm
wow! well done seb! you should check out brians synth. it was he who inspired me to start work on this. its such a simple idea but works so well!
i love the use of the arduino to produce the signals. are you sending it midi data or something to pulse the digital pins? i’ve just dug my arduino out to try a few things.
February 23rd, 2008 - 1:36 pm
Yeah, i just watched Brian’s synth and it is AMAZING, very expressive, mysterious.
I send the Arduino MIDI data, and it simply maps the note number and velocity to a cycle loop delay time and sets the state of the digital pins which are directly connected to the RGB lines. This is more of a simple test, but it is all so much fun!
February 23rd, 2008 - 2:05 pm
aye, his synth is most impressive! i’ve come close to producing nice vertical stipes of audio reaction colors with an envelope follower and a host of different nand gates and other ic’s, but it doesn’t have anywhere near as much control as his. as you say, very mysterious!
i’ve just downloaded the new arduino software for my g4, its installed and ready to go. i’m going to try and feed an audio signal into the analogue pins to creat pwm signals from the digital outs to see what happens. if nothing else it saves me from doing house work…. ;o)
my knowledge of arduino is limited, and half of your sentence above confuses the hell out of me….. i’m more hardware orientated than micro controllers, but i’m slowly learning for this led wall i’m (still) working on, and have been for the past year.
I’m looking forward to seeing what you come up with!
February 23rd, 2008 - 10:55 pm
so to clear up my sentence above; Ableton Live is playing a monophonic drumbeat. This MIDI data is also routed out to Max/MSP. A Max/MSP patch is scaling and routing the MIDI pitch and note-on velocities to a serial port, to which the Arduino is connected. The pitch byte sets the colour bits (only three bits worth of information) and the velocity byte sets the delay time of a loop. I have posted the Arduino code and the max patch now.
February 23rd, 2008 - 11:19 pm
nice, thanks for clearing that up!
i dont have MAX unfortunately, but i did manage to get some nice results with the PWM channels on the arduino using an audio input split into bass mid and treble frequencies with an additional circuit feeding the analogue in pins.
you could probably use the uVGA module to create the Vsync and Hsync signals, but that would be a huge waste of such a device. from what i now understand, arduino isnt capable of producing the correct timing info, so what ever i had working must have been a fluke. there’s a guy on brians vidisynth forum who is trying to recreate them on a PIC, so it’ll be interesting to see what he comes up with.
April 13th, 2008 - 4:07 pm
hi!
at first! cool works above! keep on going ;]
i add a little of the fun from my own just with more simple analogue way by playing with some cables etc. i hope to have some time to make more complex system with it to be able to control the output a bit more…
two videos here: http://www.lostpostservice.net/img/pash_galllrija/080406-pvx/pvx_imgs.html