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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: Fri Jul 29, 2011 3:45 pm Post subject:
Inventor's Percussion Lunetta Subject description: A product under development |
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Hi, tonight I've decided to begin creating a Lunetta Percussion product and put my name on it. When completed I will offer it for sale at a reasonable price.
It just so happens that when I piece together all the interesting Lunetta circuits that I've been working on lately I get a nice little percussion machine! Isn't that nice? So I'm going to take a breadboard and a tupperware container and some alpha pots, chips, etc. and make a nice little Lunetta Percussion box.
So you can follow the development and make your own one of these, I will document my progress in this thread. Well, also for the fun of it. So here goes, listed block diagram to follow...
Les _________________ "Let's make noise for peace." - Kijjaz |
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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: Fri Jul 29, 2011 3:55 pm Post subject:
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Here's a list of the blocks in the block diagram (i'm too lazy to draw it so use your imagination, the flow is very simple):
SRFF oscillator
4020 counter
Logic
Aggregator
Percussion circuit
Buffer
Spatializer
Dual buffer
1/8" stereo jack
Here is how it works: The SRFF oscillator is a discretely implemented Set-Reset Flip-Flop with a pair of RC filters added in feedback, and it clocks the 4020 counter. The counter outputs go into some logic followed by an aggregator, resulting in a Boolean Sequencer specifically designed for this ILP product. This drives the Percussion circuit which sends the percussion audio into a buffered Spatializer followed by an 1/8" stereo jack.
So it's a little bit complex but that's ok because it will generate some nice synthesized percussion type sounds and they will be spatialized for good stereo effect. More details to follow later.
Les _________________ "Let's make noise for peace." - Kijjaz |
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inlifeindeath
Joined: Apr 02, 2010 Posts: 316 Location: Albuquerque, NM
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Posted: Fri Jul 29, 2011 4:51 pm Post subject:
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Most of that went over my head as with most of your projects, but I can't wait to see what you come up with! _________________ http://www.youtube.com/user/borisandfef |
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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: Fri Jul 29, 2011 6:36 pm Post subject:
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inlifeindeath wrote: | Most of that went over my head as with most of your projects, but I can't wait to see what you come up with! |
Well that was just a quick overview so it sounded overly technical, I'll try to explain things better as we get into the details. Like now, for instance, we're ready for our first circuit design: the SRFF oscillator.
See the image below for a schematic of this oscillator. I cooked up this curious circuit for the Lunetta Challenge when my grab bag of chips did not have any Schmidt trigger gates. Normally you'd use a single-gate oscillator based on say a 40106 Hex Schmidt Trigger Inverter, but I didn't have such a beastie or anything like it so I had to get creative.
Calling myself "Inventor" or sometimes "reInventor" more accurately, I didn't choose to look up a multiple gate oscillator but rather decided to imagineer something creative. I thought of the Set-Reset Flip-Flop which is made of two cross-conected NAND or NOR gates and set about figuring out some kind of way to make it oscillate.
After a little percolation in the old noggin, I did in fact come up with such a circuit and I have built it twice now with different chips and parts and it works just fine. As is normally the case, I'm sure someone out there reading is rolling their eyes, thinking "Yeah, you reinvented the wheel again!", and that's just fine. There's nothing wrong with reinventing the wheel, otherwise we'd still be riding around on prehistoric cart wheels chiseled out of stone on our cars, lol. OK, back to the circuit.
The way a Set-Reset Flip-Flop works is that you apply a one to the Set input and the Q output goes to one while the Q- output goes to zero. Then whenever a 1 pulse comes along on the Reset line the output toggles, awaiting the next Set pulse, and so on. Thinking about this behavior we sort of kind of have the guts of an oscillator: a thingie that toggles when the inputs change values.
From there it was just a matter of inspiration in imagining where to put some resistors and capacitors to cause a sustained oscillation and we end up with the circuit shown in the schematic below.
As to the frequency of oscillation, we have R equal to 100k Ohms and C equal to 0.1u Farads, so the RC time constant is 10 milliseconds. We'll see about 1.5 time constants before a gate triggers at Vdd/2, and there are two of them, so the total oscillation period should be about 30 milliseconds, resulting in about a 33 Hertz clock frequency with the potentiometer at full value. Minimum value will be about 20 times faster, or 660 Hertz.
That's a pretty good range of frequencies. Now, this is the tempo clock of the percussion instruments and 660 Hertz is a wee bit fast for our drums, lol! No problem though, this clock is going into a 4040 binary counter chip which will divide it down.
Another thing to note about this circuit is that it produces a two-phase clock output which can be handy, and also since we are adjusting only one side of it, it will sort of gallop along with unequal duty cycle. No matter, the binary counter chip inherently evens up the duty cycle of such clocks to 50% by it's nature of operation.
One final "note" (oooh, such PUN-ishment!) about this oscillator is that instead of leaving us with five free inverters that we don't need, the spares are two quite useful free NAND gates. We'll see them come into play later.
OK, I did get a little bit technical there - it was necessary for a detailed explanation and even then I skipped over some stuff. Here's hoping you now understand this circuit fairly well and find it to be interesting or at least entertaining!
Les
Description: |
SRFF Oscillator schematic image |
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_________________ "Let's make noise for peace." - Kijjaz |
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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: Fri Jul 29, 2011 8:07 pm Post subject:
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After some more designing I've got the next three subcircuits drawn, forming the Boolean Sequencer from the 12 bit counter, the Logic, and the Aggregator. See the schematic below for details.
Here we have the LSB of Q4 and MSB of Q7 driving the Logic which really only needs to be a single gate here. This range of bits gives a reasonable tempo in the middle setting of the clock.
The logic gives us three terms, two of them directly from counter outputs and one from a logic function. There is an art to selecting the logic section of a Boolean Sequencer and in this case since we are creating a drum rhythm we don't need an overly complex set of logic expressions. Also the logic works with this particular design of an aggregator in the following way.
Think of the aggregators as being adjusted fully to one side or the other. The top pot in the up position effectively selects the LSB of Q4 for delivery to the percussion circuit's input. The same for Q6 with the bottom pot in the down position. If both pots are spun in the opposite way then only the NAND term is selected. Also the NAND and Q4 or the NAND and Q6 can be selected. That is the extent of full range selection.
Those positions will give nice drum rhythms of moderate complexity and different rates, however these being pots they may be adjusted to any intermediate value in which case the three terms get weighted and applied to the input. The presumption here is that a different sound will occur when different input level transitions are presented to the percussion circuit's input.
So overall we get a lot of variety of sounds, or so I hope, from only one NAND gate and two pots. Next up we have the percussion circuit in which I have super simplified things by using a single pot for the input and feedback resistors, plus a separate pot for the RC filter. This reduces the adjustment of pots from a 3D space to a 2D space to hopefully simplify things for the performer so it becomes easier to find the sweet spot of audio.
The nice thing about this arrangement is it requires only the two spare NAND gates left over from the oscillator, saving us a whole chip in the process. We now have our percussion sound!
Les
p.s. I'm designing the entire circuit before constructing and testing anything. This will save time overall, especially with mounting pots and soldering and such.
Description: |
Boolean Sequencer Schematic Image |
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Percussion KS schematic image |
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_________________ "Let's make noise for peace." - Kijjaz |
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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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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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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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Inventor
Stream Operator
Joined: Oct 13, 2007 Posts: 6221 Location: near Austin, Tx, USA
Audio files: 267
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Posted: Tue Aug 02, 2011 9:22 am Post subject:
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I waited until morning to use the Dremel tool for machining the enclosure so as not to annoy the neighbors. I didn't have the right size bits so I ended up spending a lot of time grinding just to get some holes but it was worth it as the final result is quite nice. I also used a coarse drum sander attachment to make a nice finish on the unit. Here are outside and inside photos with parts installed. This is fun!
Les
Description: |
Rear view of unit, showing 1/8" jack, power switch, and 4 pots |
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Inside view with parts installed. |
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1.45 MB |
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_________________ "Let's make noise for peace." - Kijjaz |
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tony void
Joined: Apr 26, 2011 Posts: 40 Location: Parma, Ohio
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Posted: Tue Aug 02, 2011 9:58 am Post subject:
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Loooking goood. ( It's hard to emulate an accent in text, but that supposed to sound like Freddie Prince Senior from the old sitcom Chico and the Man.)
Seriously nice work! |
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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 Aug 02, 2011 10:45 am Post subject:
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Thanks, it's a bit of a kludge but that's OK for my first enclosure-based product. Most importantly I'm having fun doing this project!
Les _________________ "Let's make noise for peace." - Kijjaz |
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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 Aug 02, 2011 5:03 pm Post subject:
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Well, it's done! yay \o/ There was one issue, I forgot to hook up ground to the output jack so I got no sound at first but the error was easy to spot. Oh, and one other thing is that I ended up wiring the logic to the counter outputs in a slightly different order and would up with a much faster tempo to the circuit. It's useful for high energy techno, etc. now. That's just how it turned out. Now to rest a bit and then put it up for sale.
Les _________________ "Let's make noise for peace." - Kijjaz |
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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 Aug 02, 2011 11:35 pm Post subject:
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After demonstrating this new toy on the em radio for a while, I have decided to keep it rather than sell it. It makes a lot of really cool sounds and it's a fine addition to my music performance collection. In fact, I think I'll make more of these boxes and have a little collection of them plus a mixer and all that. Should be great for doing radio shows, which I may get back into soon.
Les _________________ "Let's make noise for peace." - Kijjaz |
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