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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
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Inventor
Stream Operator


Joined: Oct 13, 2007
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PostPosted: Mon Jul 25, 2011 5:01 am    Post subject: Go read my blog!
Subject description: (Thanks to all who did!)
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The title says it all, click here for teleport:

http://reinventor.wordpress.com/

Les

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slacker



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PostPosted: Mon Jul 25, 2011 2:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice I'll have to give that percussion thing a try.

I might be being stupid, but with your guitar pickup design how are you generating a current in the strings if they are connected to ground via the bridge?
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PostPosted: Mon Jul 25, 2011 2:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

slacker wrote:
Nice I'll have to give that percussion thing a try.

I might be being stupid, but with your guitar pickup design how are you generating a current in the strings if they are connected to ground via the bridge?


Ty slacker, I hope you enjoy the percussion circiut.

About the guitar pickup, people ask me that question a lot. They reason: "It's a wire, and a wire is a short, so how can there be a voltage across a wire and a current flowing through it?" The answer is that it's a tiny electric generator. You look at an automobile generator which is nothing but magnets and wire essentially, yet you do not ask that question about the generator.

Well, we had actually thought of calling this circuit "the Generator" because it is essentially an extremely weak little half-turn times six generator. That idea failed horribly when guitarists imagined getting themselves fried to char by their generator guitars, lol. They are quite an imaginative bunch of folks. So we abandoned that name.

Think of it like this: the section of each string that is in the magnetic field and vibrating is like a tiny little time-varying battery. This battery has no juice, it takes the energy from the motion of the string and converts that into a super teeny little electromotive force, or EMF. This EMF may be modeled as a Thevenin equivalent voltage soure or as a Thevenin equivalent current source, your choice as they are two sides of the same coin so to speak.

I hope my explanation is clear enough, and thanks for reading my blog!

Les

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Stream Operator


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PostPosted: Mon Jul 25, 2011 3:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

Oh, I just realized that I answered the wrong question in part. You asked me how can the strings generate a signal when they are grounded and I explained the first part of it which is that they ar little EMF generators.

The rest of the answer is that the EMF generators are much like time varying batteries as I explained, and one end is connected to ground - not the whole thing to ground. When you connect the negative terminal of a battery to ground, you do not ask "how can the positive terminal deliver a voltage when the battery is connected to ground?"

Just like the generator question about how can it develop a voltage, the same thing applies. We tend to think of substantial things like an automobile generator or a battery as obeying the laws of electronics, but when we see a teeny little thing, well, we make assumptions that are not necessarily valid.

I'll add that in electrical engineering they teach us that there is no such ting as an ideal wire. When it comes to small signals or fast signals, or strong signals, wire becomes very much a circuit element.

Lesson Learned

Les

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madskill42



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PostPosted: Tue Jul 26, 2011 2:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Yeah, it was kinda like that, when I read this Smile It's so dead simple, it's amazing! Design following KISS rule (Keep It Stupid Simple) for sure Smile

I'm about to get some NAND gates CMOS today, along with few pots to try it out. But I've got a few questions:

1. "Vin" is input pulse as I understood, but will be 4017 pulses sufficient for this kind of stuff? I hope so, but as I read in your thread about your other Karplus Strong project (fascinating piece of work, hands down), more shorter pulse you can offer, it will sound much more percussive, right? But I don't quite know how to control 4017 pulses (PWM, as I suppose). Is there some schemo for this kind of stuff? May this work for PWM?

EDIT: Sorry, I forgot about my second bag full of questions!

2. NAND gates in 4011 will work, right? Hopefully, all four gates will work, so I can use them all. But as I was searching for suitable NAND gate, I came across some of these chips that have NAND gates with more than 2 inputs. Can I use them to somehow modulate resulting sound or just somehow change overall characteristics?
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PostPosted: Tue Jul 26, 2011 2:55 am    Post subject: Reply with quote  Mark this post and the followings unread

madskill42, thanks and i'm glad you're a fan of simplicity in design. It seems that so many people want to overcomplicate things but that's not my approach. about your two questions:

1. Yes, most likely a short pulse will be more percussive. The RC time constant of Rin and Cin will have a big indluence on the effective input pulse duration as they work together to form a high pass filter that creates input pulses from the clock edges. I'd say that smller values of Rin * Cin would give shorter equivalent pulses.

Also you mention you have some multiple input NAND gates, try one of those with a 4020, 4040, or 4060 counter output of three adjacent bits to get a narrow pulse, perhaps.

2. I would experiment with the two-input circuit first, then try a three or more input circuit for fun next. The things to try on say a 3-input NAND gate are either apply two inputs or have two RfCs feedback paths to shape the sound in a more interesting way.

If you try either of those, please report back to us with your results as that seems very interesting. Well, let us know what you discover no matter what, it will be nice to read.

Les

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madskill42



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PostPosted: Tue Jul 26, 2011 3:15 am    Post subject: Reply with quote  Mark this post and the followings unread

That was quick! Smile

Ok, I'm adding 4040 & 4020 to shopping list and I'll see what I can come up with.

I've got to say this is one of best forums I've ever been at, full of usefull informations and wise gentlemen discussion. Amazing!
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madskill42



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PostPosted: Wed Jul 27, 2011 3:41 am    Post subject: Reply with quote  Mark this post and the followings unread

Experiment conducted today is... failure I guess.

Everything I was able to get was just clicks and pops. Not those interesting sounding tones I heard in your eChuck exaples, not even slightly. Here's my testing setup:

40106 for generating clock to 4017 (4 steps with 10k pots), which was sending output to 4011 though cap and pot on pin 1 (1st gate input as datasheet says). Caps were electrolytic 0.1uF and all three resistors were switched for 100k pots. And CMOS used as NAND gate was 4011BE.

I've tried different caps (10uF & 22uF) as they were laying around me. Nothing. I bypassed 4017 and used clock directly from 40106 and result was pretty much same.

I have no idea what I did wrong. Just to be sure, DGND is digital ground, right? So can I connect it to a GND bus like a rest of chips, or it's got some special place for connecting?

Also I've noticed another strange thing. While testing on my rubbish active speakers, it sounded normal (well, just those pops and clicks), and as I connected output to notebook mic input to record a demo or something for you people to listen, it was barely usable. Signal dropped to like -60dB and I had to really push it up with gain inside DAW. And that sounded really strange, like digital hum and noise with pops. So I tried it on external soundcard (Lexicon Lambda) and signal drop was even more significant. Almost no sound at all. Can anybody shed some light on this?
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PostPosted: Wed Jul 27, 2011 6:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, I know the circuit works because I built it so let's try to examine what might be different in your setup. My first question is: "What is the frequency of your 40106 oscillator?".

Just hook your 40106 osc directly to your amplified speakers and listen. You should hear a clicking sound at note rates, like 1 click per second or 4 clicks per second or something like that. If you hear a tone then your 40106 is oscillating at audio frequencies which is too fast.

Next I would recommend using 0.1uF ceramic capacitors, not electrolytic, for two reasons. First, that is the type of cap that I used. Second, with electrolytic you might get the direction of the cap wrong which would not work.

Regarding that direction, the curved side of the diagram is minus and the flat side is plus. If you get that backward the circuit may not work (and probably won't).

Another thing is that I really liked how you attempted to simplify the situation by connecting the 40106 oscillator directly to the input of the percussion circuit... that is good testing process. The fact is that the 4017 circuit has analog output circuitry composed of resistors and diodes which may affect the operation of the circuit.

So I would recommend that you test with the 40106 osc directly into the percussion circuit, make sure you're at a 1Hz or thereabout rate with the clock, and use the 0.1uF ceramic caps. Hopefully that will work, please give it at try.

Here's wishing you good luck!

Les

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PostPosted: Wed Jul 27, 2011 6:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Frequency of 40106 was quite low, as I used it to drive 4017. I'm using 20uF cap and 10K pot combo, wild guess of that range is 40bpm to bizillion Smile

It's kinda strange that 4017 has analog circuitry, I have to seek knowledge about differences in analog and digital, where one start and other begins. As far as I know, digital (or logic) uses H&L voltage and analog everything in between.

Caps... I hoped that guy in the store will give me ceramic ones, but they moved shop last week to new spot, so he apologized and said if I won't mind an electrolytic ones. "Grrrrrrr.... (*thinks about all those headaches to come with polarity chechking*) Ok, nevermind".

Yeah, about DGND... I did little research, and found just that DGND and analog GND is used for each component respectively, and then shorted somewhere with 0ohm resistor or inductor. And DGND is supposed to have high noise inside, so maybe this has something to do with this.

Anyways, I'm going to tear 4017 out, and use just 40106 one clock. And hopefully I'll find a few suitable ceramic caps....

Take care Les
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PostPosted: Wed Jul 27, 2011 7:15 am    Post subject: Reply with quote  Mark this post and the followings unread

a quick note: I mentioned the 4017 had analog circuitry because I thought you were using it in a Baby10 configuration, but you are not? If not then forget that comment, sorry.

Les

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PostPosted: Wed Jul 27, 2011 8:11 am    Post subject: Reply with quote  Mark this post and the followings unread

nope... I just cannot make it work...

Here's few pics of breadboard:

http://img829.imageshack.us/img829/825/img6417j.jpg
http://imageshack.us/f/812/img6418w.jpg/
http://imageshack.us/f/37/img6420z.jpg/
http://imageshack.us/f/199/img6419fk.jpg/

and I'm also uploading video on youtube as I speak (eghm, type Smile ) ... Maybe it will help you Les (or anybody else) with solving my damn problem Sad


EDIT: There's my hopeless tweakage...

http://www.youtube.com/watch?v=U4EmTJAuwOM
http://www.youtube.com/watch?v=zH8ihf_eSfc
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PostPosted: Wed Jul 27, 2011 10:14 am    Post subject: Reply with quote  Mark this post and the followings unread

The videos are helpful because they tell me that you are close. Wit the pots at full value you're getting a thud followed by a low frequency ring, which is very nearly what we need, it's just that that ringing needs to be higher in frequency.

Here's the first adjustment to try: set Rf2 and Rin to max, adjust Rf1 to half value. That should double the frequency of the ringing. Next vary Rf1 across the full range of it's value and notice what happens. The ringing should change in frequency until you hear something rather percussion-like. It will be a thump followed by a ring, crude percussion yet percussion still.

Now the second thing I want to do is explain to you about tweaking pots. In the video you have all three pots at full scale and you have something close to what you want coming out of the speakers. Then you turn one pot to zero, the next pot to zero, and finally the third pot to zero then the video ends. This is not the way to adjust pots.

Think of three pots as each positioning a marker on an x,y,z axis. when you adjust any of the pots, the point that those markers identify within the xyz space (cube) moves accordingly. What you want to do is move the point through that space, imagining it to be like some fish in a tank that wants to swim around all the places in the tank, or like some spacecraft that need to chart the region.

Well, with that analogy, what you did was put the point at the far corner of the cube, then proceed to move the point along the Z axis to zero, then along the Y axis to zero, then along the X axis to zero. You moved along the corners and never even entered the middle of the space that you wanted to explore! In other words, in the video at least, you didn't give the circuit a chance to work at all.

So, now you are armed with the power of knowledge! Take your circuit with it's three dimensional parameterized space to explore and explore that space fully! You did the difficult part, now adjusting the pots properly is the easy part.

Best of luck, and please do not get frustrated - you are so close!

Les

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madskill42



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PostPosted: Wed Jul 27, 2011 10:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Wow, do you sleep sometimes? Smile

As soon as I'll finish my dinner, I'll try it! Thanks a lot for advices Les, I appreciate it very much, I really do...

Yeah, I know what you meant by that tweaking in 3d space (I was tweaking it for like half an hour, just to try different combinations.) For me personally, coming from bit of coding and programming, it's more like math expression. If you've have a pot (let's assume that it has x steps), than you have x1 possible steps, or adjustments. If you got two of them, controlling each controlling different thing, you've got a x2 possibilities. Generally, if you have y number of pots, your possible amount of adjustments is xy.

But that space explanation is very clever idea. It's kinda same as mine, but you don't bother people with math, hehe Smile

EDIT: As soon, as I got this working, 4012 is next one to try...
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PostPosted: Wed Jul 27, 2011 10:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, in fact I have been sleeping in naps in between these posts, haha! I'm so glad to read that you are not discouraged. I'm doubly glad that you understand the search space concept. Here's an additional thought that will help.

Although we really do have a three dimensional space here, we can think of it as having about 10 slices, where the Rf2 by Rin planes are stacked along different values of Rf1. That's because Rf1*Cs perform one function while Rf2 / Rin perform another function.

That said, these functions do interact because the NAND gate is linearly biased. It's just that it helps to separate things according to what they do.

Hope you find that additional little bit of info useful.

Les

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PostPosted: Wed Jul 27, 2011 2:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

My final result: I giva up. At least for today. I tried turning those knobs how you said Les, few squeeky sounds got through. After many drop-outs (from time to time scheme just gave up & stopped doing anything), I got mad a pulled everything from the breadboard and started over. Results were (kind of) better:

Electrolytic caps works fine, practically same as ceramic ones.

Second "unit" was built, right next to previous one, controlled by same clock, but different tuning. Both very paired via diodes (to form pseudo-ringmodulation). Sounded interesting. 22uF cap across output and ground was functioning as LPF and gave a click nice little "round" sound.

I'll try use 4020 counter tomorrow as clock...

Overall, it's disappointing. I was hoping for something along tonal drums or something more melodic than just click. I'll probably just record few tweakage to computer to broaden my sample library.

Or maybe I'm just very, very tired Smile

Les, could you please post some samples of your results, so I can compare it to mine? That would be cool, to see how it should actually sound. And thank you for your co-operation today!
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PostPosted: Wed Jul 27, 2011 4:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sure, that's easy enough to do... Here is your sample! It's one minute long and the loopable minimum length is only a few seconds so anyone who wants to add it to a song may do so freely.

I'll work on an exact schematic next.

Les


PercusionsKS.mp3
 Description:
Percussion Karplus Strong sample

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 Filename:  PercusionsKS.mp3
 Filesize:  1.04 MB
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PostPosted: Wed Jul 27, 2011 4:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK here is your schematic. I figured out two of the resistor values and labeled the caps, oh and as heard there is an RC filter on the output and a bit of loading circuitry that should not affect it much. I took off the filter cap and just got crisper drums so not problem there.

The unlabled resistors are either 100k or 10k, probably 100k. I cannot tell red from orange on these resistors and i have no multimeter, sigh. Best of luck to you.

Les


PercussionKS.jpg
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a (more) detailed schematic
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PostPosted: Fri Jul 29, 2011 2:31 am    Post subject: Reply with quote  Mark this post and the followings unread

2 days spent at money generatin process (you know, work Smile ), now I can access computer with internet access.

That sample sounds very cool! I wish I could squeeze these sounds out! I'll have next shot after a weekend, because I'm heading out of town. That new schemo looks promising, too. I'm definitely looking forward to try it again!

I very like your result. My head is just spinning with ideas of further sound processing. But have to find some suitable way how to sequence it properly, if somehow that circuit is gonna work...
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PostPosted: Fri Jul 29, 2011 2:42 am    Post subject: Reply with quote  Mark this post and the followings unread

madskillz42, and others, please read the comments that follow the article on my blog related to this issue. Someone else could not reproduce the circuit, and yet others have done so with success. So I set about testing the EXACT same circuit and guess what?

It only works with certain NAND chips! Oh no! And the ones it works with are the surplus ones, not the new ones. That's good in that they are cheaper, and bad in that you gotta hunt for them. The chips that work are the HEF4011 chips, and not the CD4011 chips.

Another good thing is that i can tell you where I got the surplus HEF4011 chips: from Electronics Goldmine. Also another good thing is that they work in both NAND and NOR chips, do if you happen to have an HEF4001 chip, try that. IF not, buy both the HEF4011 and the HEF4001 so you can have two circuits with subtle differences.

Sorry for the inconvenience. Oh, and I have exact values for you.

C1 = C2 = 0.1u
R1 = R3 = 100k
R2 = 49.9k

And the values do not seem to be all that critical, for example it works with the above values but the input resistor R3 set to 149.9k, which is a lot different yet it still works. I bet you can adjust the frequency of the chirping part of the percussion with R1.

I apologize for any inconvenience this may have caused you but really it would have taken a degree of perfection on my part to see this possibility that I guess I just don't have. Best of luck and happy circuit building.

Les


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The simplified circuit from which the values are referenced
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PostPosted: Fri Jul 29, 2011 3:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Ahhhhh.......

HCF4011BE

is what I got!

Damn you chips, why are you so different! Confused

On the other side...


let the hunt begin! Twisted Evil
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PostPosted: Fri Jul 29, 2011 3:55 am    Post subject: Reply with quote  Mark this post and the followings unread

What are you driving with it? Oh yes, you said - amplified speakers or a notebook's line-in. both should work. * should... *

Les

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PostPosted: Fri Jul 29, 2011 4:04 am    Post subject: Reply with quote  Mark this post and the followings unread

So both HCF & HEF should work?

EDIT: Silly question, I should read your post twice. Sorry Les
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