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Stream Operator
Joined: Oct 13, 2007
Posts: 6221
Location: near Austin, Tx, USA
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 Posted: Mon Feb 07, 2011 11:58 pm Post subject:
The Moscillator
Subject description: Named after our Howard |
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Hi it's me again, heh, this time reporting my discoveries about my implementation of a ring oscillator that I have named the Moscillator. It's actually an analog ring oscillator, not the usual digital one and it's expandable in a unique way that I will describe here. So what is it?
Well you may be familiar with the ring oscillator, not to be confused with the ring modulator which is a completely unrelated circuit. All you have to do is hook three inverters in a loop and they will oscillate a three-phase square wave. That's the basis, the simplest, the most fundamental form of a ring oscillator. For purposes that I will reveal later I think of them as triangular loops, not circular or three inline with feedback wire.
Well it turns out that you can put pretty much any inverting, delaying thingamajig in a triangular loop like that and it will oscillate. So when I needed a sine-ish like interesting musical oscillator for 1:11's controller project, I imagineered putting low-pass filters made of opamps in such a loop. Long story short, I did and it sounds good.
Actually it makes sort of a wailing sound but kind of sine-wavy and too much high frequency to be a ghostly wail. Put it into a Karplus Strong loop, though, and it sounds like a haunted house on Halloween! Now that is exactly what we need for our project - something wild and freaky to add to the mix, ghostly moaning...
Other details of the circuit is you need some sort of limiter to give it a smooth sound and waveform shape instead of the harshness of a square wave oscillator, so I added some LEDs to the circuit. I'm not going to draw the circuit for you at this time because I don't want to release information about the product design too early, but if you've got some skillz, you can imagine what it looks like.
Now how do we expand this circuit in a novel way? Next post!
Les
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Inventor
Stream Operator
Joined: Oct 13, 2007
Posts: 6221
Location: near Austin, Tx, USA
Audio files: 267
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| Posted: Tue Feb 08, 2011 12:18 am Post subject:
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As it turns out, my master's degree thesis was on ring oscillators. Digtial ones intended for high speed CPU clocking. I won't get into all that except to describe the one key principle of the thesis, which was the geometric generalization of the ring oscillator.
Huh? Say whut? No man, it's simple. Imagine a sheet of hexagonal graph paper, just like ordinary graph paper but little triangles forming hexagons are printed on it. You can buy paper like that. Now pick a triangle and draw three little amplifier symbols on the three sides of the triangle, representing a ring oscillator. OK, now on an adjacent triangle you have two free unused sides. Draw two more little amplifier symbols there. Now you've got the simplest version of a ring oscillator array.
Well, it turns out that you can easily draw more and more amplifiers on more and more of the graph paper until you fill it up. Our idea was to make a distributed oscillator on a PC CPU chip that had low skew because of aggregation. That occurred due to the way we resolved nodes with multiple outputs on them, which we did by shorting the inverters together. But I have wandered off of the topic, anyway here's the deal for music:
We can use inverting filters with limiters and multiple inputs to populate this array of little amplifier symbols. Depending on how we do it, there will be some interaction between sections of the array that have different delays or different gains or whatever. This interaction will be musically interesting, if we do it right, and we can be wild and creative about how we do it too. Just follow a few simple rules like gain > 1 on average and what I have already mentioned, stuff like that, and we will have a working musical oscillator array.
Imagine a sea of potentiometers and you dial them to create interesting waveforms. Or better yet, a sea of cadmium sulfide cells (resistance varies with light) and now you can treat this weird oscillator like some kind of multi-arrayed optical theremin thingie.
There's more, so much more, like you can get 3D or even ND with it. Make a soccer ball or other Bucky-ball. Wire it up as a 3d sculpture and play it like an instrument. OK, you get the idea. This thing is really wild and fertile ground for creative engineering and musical expression.
There you have it: I give you "The Moscillator"!
Les
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DrJustice
Joined: Sep 13, 2004
Posts: 2112
Location: Morokulien
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| Posted: Tue Feb 08, 2011 4:55 am Post subject:
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Neat one, Les!
I have some questions on the array configuration.
Will the whole array oscillate at the same frequency, even if the frequency determining factors (e.g. slew rate) that can be added to each amplifier are different? Or in other words, is a sympathetic effect across the network occurring at all times?
If one changes the frequency determining factor of one or more amps, what will happen at the various nodes in the network? Will the frequency and phases change differently around the network, before settling into an equilibrium? Or is it possible to get the network to self modulate and 'err'? If any modulation effects are taking place, will they take enough time to create audible sweeps and wobbles etc.?
I haven't actually thought any of that through, just throwing up those q's... 
DJ
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Inventor
Stream Operator
Joined: Oct 13, 2007
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Location: near Austin, Tx, USA
Audio files: 267
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| Posted: Tue Feb 08, 2011 8:58 am Post subject:
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| DrJustice wrote: | Neat one, Les!
I have some questions on the array configuration.
Will the whole array oscillate at the same frequency, even if the frequency determining factors (e.g. slew rate) that can be added to each amplifier are different? Or in other words, is a sympathetic effect across the network occurring at all times?
If one changes the frequency determining factor of one or more amps, what will happen at the various nodes in the network? Will the frequency and phases change differently around the network, before settling into an equilibrium? Or is it possible to get the network to self modulate and 'err'? If any modulation effects are taking place, will they take enough time to create audible sweeps and wobbles etc.?
I haven't actually thought any of that through, just throwing up those q's...
DJ
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DJ, I only know a little bit about this analog approach, but I believe the answer is: it depends. I say that because it depends on how strictly or "stiffly" you combine nodes. First off, I only defined one type of network which we can call the "side" network, in which the amplifiers are located at the triangle sides. The other type let's call "vertex" has the amplifiers located at the vertices. Depending on which type you use and how you resolve situations where outputs meet, you will get different behavior.
In the master's thesis and on the patent that resulted from it, we described both types, but we had to choose only one for the application and I think it was a "node" network. In that case, each inverter was connected to a third of all the other inverters and there were only three unique electrical nodes in the whole circuit. That way all the inverter outputs "fought" each other over the small RC delays of the wiring between them, resulting in an averaging of their process variation. This was really good for us because it meant that the whole chip would go 1-2-3-1-2-3- and so on, in three phases with low skew across the whole chip.
Now unfortunately industry ran into it's heat and skew limits on processors using the H-Tree method of clock delivery which has it's own advantages and disadvantages, and they went multi-core instead of distributed. Eh, what you gonna do. Our work was overlooked by Intel even though it might have allowed them to push the clock envelope even further than the H-tree did. Back to the topic.
I said all that because in music we would like the opposite. We want that skew. We also want propagating waves in fascinating reflections across the network of filters. Rather than desiring uniformity, we want as much uniqueness as possible.
When I built a circuit with pots to adjust the filters, and two triangles connected together, I did it in such a way that the gain and delay were interdependent. I have discovered that this is not desirable because adjusting one triangle too far would cause both triangles to stop oscillating. Of course we can design that out or minimize it with series resistors on the pots but ideally we would like to resolve the issue.
For that I would suggest a circuit topology with inverting amplifiers on the branches and low pass 3-input filters on the vertices. could do that with one fixed 5k resitor tied to the wiper of a pot who's ends go to the other two inputs, and a cap to ground from the wiper. this would make a triple rc circuit at each vertex that did not affect the gain which resulted from the inverting amps at the branches. I think that design would be more stable in terms of failure to oscillate.
So rather than directly answering your questions, drJustice, I have described more of what I know about the Moscillator in the hopes that you will see the general picture well enough to imagine your own answers. In other words, the answer is "it depends"!
Les
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DrJustice
Joined: Sep 13, 2004
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| Posted: Tue Feb 08, 2011 9:41 am Post subject:
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| Inventor wrote: | ...In other words, the answer is "it depends"!
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I guess it does... Somebody should build that soccer ball network with light sensors - if it sounds nice it should become a FIFA standard to make soccer more interesting 
DJ
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Inventor
Stream Operator
Joined: Oct 13, 2007
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Location: near Austin, Tx, USA
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| Posted: Tue Feb 08, 2011 12:16 pm Post subject:
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I am a proponent of electronic sports equipment. Why not know the exact position, velocity, acceleration of the ball at all times?
Les
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DrJustice
Joined: Sep 13, 2004
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| Posted: Tue Feb 08, 2011 12:25 pm Post subject:
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^ That was suggested a few years ago. The main idea was to control cameras IIRC. I don't know if anything came of it.
DJ
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Stream Operator
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| Posted: Tue Feb 08, 2011 2:27 pm Post subject:
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Typical. I had the idea almost ten years ago. When an idea's time has come, everybody thinks of it....
Les
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telbonic
Joined: Jan 08, 2010
Posts: 39
Location: uk
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| Posted: Thu Feb 10, 2011 2:18 am Post subject:
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| DrJustice wrote: | | Inventor wrote: | ...In other words, the answer is "it depends"!
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I guess it does... Somebody should build that soccer ball network with light sensors - if it sounds nice it should become a FIFA standard to make soccer more interesting
DJ
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It's called football everywhere in the world (except where they play "American Hand-Ovoid"). Because of the feet. And the balls.
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DrJustice
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| Posted: Thu Feb 10, 2011 4:06 am Post subject:
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| telbonic wrote: | | "American Hand-Ovoid" |
I chose the continued use of "soccer" in this thread to differentiate for the benefit of our US American brethren. The handovoid, being constructed of digons, as opposed to pentagons or other odd sided polygons, is of course not suitable as a structural model for a Moscillator network
DJ
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
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Posted: Sun Feb 13, 2011 10:01 am Post subject:
Re: The Moscillator
Subject description: Named after our Howard |
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Hi --
This is similar to a number of circuits I have built. For example, my fifth-order chaos generator (decature oscillator):
http://home.comcast.net/~ijfritz/ch_cir4.htm
Note that these include integration and damping in each stage, as opposed to the more common approach of putting integrators in a ring and adding a single limiting element.
Also note that I have ways to cross-couple the nodes to make a more versatile system, somewhat similar to your proposal to use a triangular lattice.
You should be aware that there is a whole field, and a huge body of literature, on coupled oscillators on a lattice. These are used to study nonlinear spatio-temporal dynamics of complex systems. You might be able to get some ideas from this work.
Ian
| Inventor wrote: | Hi it's me again, heh, this time reporting my discoveries about my implementation of a ring oscillator that I have named the Moscillator. It's actually an analog ring oscillator, not the usual digital one and it's expandable in a unique way that I will describe here. So what is it?
Well you may be familiar with the ring oscillator, not to be confused with the ring modulator which is a completely unrelated circuit. All you have to do is hook three inverters in a loop and they will oscillate a three-phase square wave. That's the basis, the simplest, the most fundamental form of a ring oscillator. For purposes that I will reveal later I think of them as triangular loops, not circular or three inline with feedback wire.
Well it turns out that you can put pretty much any inverting, delaying thingamajig in a triangular loop like that and it will oscillate. So when I needed a sine-ish like interesting musical oscillator for 1:11's controller project, I imagineered putting low-pass filters made of opamps in such a loop. Long story short, I did and it sounds good.
Actually it makes sort of a wailing sound but kind of sine-wavy and too much high frequency to be a ghostly wail. Put it into a Karplus Strong loop, though, and it sounds like a haunted house on Halloween! Now that is exactly what we need for our project - something wild and freaky to add to the mix, ghostly moaning...
Other details of the circuit is you need some sort of limiter to give it a smooth sound and waveform shape instead of the harshness of a square wave oscillator, so I added some LEDs to the circuit. I'm not going to draw the circuit for you at this time because I don't want to release information about the product design too early, but if you've got some skillz, you can imagine what it looks like. |
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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| Posted: Sun Feb 13, 2011 10:25 am Post subject:
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| DrJustice wrote: | | ...Will the whole array oscillate at the same frequency, even if the frequency determining factors (e.g. slew rate) that can be added to each amplifier are different? Or in other words, is a sympathetic effect across the network occurring at all times? |
If it has regular oscillations, then yes. Coupled systems like this eventually phase lock to oscillations at a single frequency, even if there are different circuits at each node. There may be more than one frequency, each corresponding to a different pattern. These are called "eigenmodes". The general solution to the system may include a superposition of eigenmodes. Which ones are actually seen in an experiment depends on how the system is started up (initial conditions).
But often these systems are chaotic, ie they have irregular oscillations. These may vary both in space and time. An of course there is no guarantee that any old system you put together will oscillate. It may settle at zero or run to the rails.
Ian |
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Inventor
Stream Operator
Joined: Oct 13, 2007
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Location: near Austin, Tx, USA
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| Posted: Mon Feb 14, 2011 1:19 am Post subject:
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Thank you Ian, nothing new under the sun eh? I wonder about my work sometimes, if it is rediscovery or discovery and often the prior. The mesh idea was patented with myself as one of the inventors so that kind of makes me feel like it's original. However, I do not recall if we generalized the patent to include any inverting circuit at each location, or if it was specific to inverters.
At any rate, the patent is now about 15 years old. How far back does the notion of the triangular mesh go with these oscillators? I don't know how original the work is now. Thanks for your enlightenment though, very astute observations!
Les
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DrJustice
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| Posted: Mon Feb 14, 2011 5:31 am Post subject:
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^ Some good info from Ian indeed. Interesting chaos circuits too
DJ
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Stream Operator
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Location: near Austin, Tx, USA
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| Posted: Mon Feb 14, 2011 5:38 am Post subject:
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yeah chaos seems really interesting, i may get into that someday soon.
Les
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frijitz
Joined: May 04, 2007
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| Posted: Tue Feb 15, 2011 8:17 pm Post subject:
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Hi --
This is turning out to be quite interesting. I took the five integrators and nonlinearities in my chaos box and hooked them up in a double triangle configuration. There are many circuit variations available because I can include the nonlinear elements or not, and I have different I/O polarities available. There are many interesting oscillations -- some chaotic, some not. The system tends to be touchy in the sense that it runs off to the rails easily and often doesn't come back. But there are lots of new patterns there anyway.
Thanks for the great idea, Les!
Ian |
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Stream Operator
Joined: Oct 13, 2007
Posts: 6221
Location: near Austin, Tx, USA
Audio files: 267
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| Posted: Thu Feb 17, 2011 5:05 pm Post subject:
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Yay \o/ exciting discovery, Ian! I love it when we spark each other's imagination! Please keep us informed and post samples too if you can...
Les
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