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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
5 Note Lunetta
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garcho



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PostPosted: Tue Oct 09, 2012 9:16 pm    Post subject: 5 Note Lunetta Reply with quote  Mark this post and the followings unread

Howdy y'all, I've been noodling on the breadboard and drew this up so I thought I'd post here. It's a very slightly sexed-up Schmitt trigger. 5 keys, 5 knobs, 5 switches. In the process of building one, have a PCB in the tank now. Lots of fun sounds, will post some samples soon, along with some pics and PCB stuff. All suggestions welcome!

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

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PHOBoS



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PostPosted: Wed Oct 10, 2012 10:30 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks for posting, looks interesting Very Happy
I'm currently doing some vactrolled oscillator stuff myself, and I can get very nice sounds out of it, so would love to
hear some sound samples from this design.

one thing that doesn't seem right to me is how you connected U1D, U1E, U1F. assuming these are just spares and
not meant to heat your tea/coffee/soup or whatever you want to keep warm, I would only connect the inputs
to GND not the outputs Wink

or just make more oscillators out of them = more fun Laughing

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garcho



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PostPosted: Wed Oct 10, 2012 3:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
only connect the inputs to GND not the outputs


Embarassed

thanks for the extra eyes!

can you believe there's 6 oscillators on this little 1c chip?!?! I'm trying to keep the hardware part count down, so I'll probably finish building this with only 3.

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analog_backlash



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PostPosted: Thu Oct 11, 2012 4:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

An intriguing circuit - I've just been thinking about how it all works. I nearly sent you a very stupid reply, but then I realised that I was mis-reading the circuit diagram (when your interconnecting lines cross, they are connections, I think). That's where the little blobs come in handy.

I'm looking at the capacitor values attached to your keyboard. Is there any clever plan to this, i.e. are the keys in any kind of musical interval apart? Probably, a silly question for a Lunetta thread... Also, where did you geta 1u33 capacitor (or is it a 1uF in parallel with a 330nF)? I've never seen one with that value before.

Look forward to hearing the results,

Gary
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garcho



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PostPosted: Thu Oct 11, 2012 8:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
when your interconnecting lines cross, they are connections, I think

yes! every intersection is a physical one. this is how U1C becomes an oscillator, for instance.
Quote:
I'm looking at the capacitor values attached to your keyboard. Is there any clever plan to this, i.e. are the keys in any kind of musical interval apart?

yes! and what a moron I am for not posting those notes. this arrangement creates a pentatonic scale, for instance, depending on the 'pitch' resistance, the scale would be G A C D E. I arrived at the capacitor values by ear, not by calculator. Quicker for a ignoramus like myself...
Quote:
where did you get a 1u33 capacitor?

...which is how I ended up with 1u33 as a value. I used a 1u with a 330N in parallel, like you mentioned. I'm sure there's a smarter way to get the same ratios with more common values, but I was happy enough with this.
Quote:
Look forward to hearing the results

I just finished populating the PCB and it works just like the breadboard! I'll post the print image along with the corrected schematic and some video/audio soon, after I stuff the enclosure, maybe a week or so, depending on real life. Wink

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analog_backlash



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PostPosted: Fri Oct 12, 2012 12:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Ah! I thought that it might be a pentatonic scale ( the word Pentasonic in your title is a bit of a clue...). That also explains the strange capacitor value. I think that putting the 2 caps in parallel is a perfectly valid way of achieving this.

Thanks for the clairifications,

Gary
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mosc
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PostPosted: Fri Oct 12, 2012 9:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool circuit. Thanks for posting.

Just a suggestion. Don't ground unused outputs in CMOS chips, unless you know that the output will be LOW because of the way you have tied the inputs. This will be an unnecessary current suck. Idea

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garcho



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PostPosted: Fri Oct 12, 2012 9:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the tips and kind words! Any advice for how I should deal with the unused inputs in this instance?
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trav



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PostPosted: Fri Oct 12, 2012 2:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

tie unused inputs to ground, leave unused outputs hanging
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garcho



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PostPosted: Fri Oct 12, 2012 6:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Oh, that's what I thought. Messed up the schemo then misread Mosc's post. Gotta slow down! Embarassed
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PostPosted: Sat Oct 13, 2012 10:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, Trav got it right.

[didactic and not necessarily directed at garcho]

CMOS is said to use virtually no current, which is almost true. It uses current only during the transitions from high to low or vice-verse. This is because CMOS inputs have almost infinite input resistance and very small input capacitance. For practical purposes, the only current CMOS uses to to pump up or pull down the capacitance of the gate inputs. Once these capacitances are charged up or pulled down, no more current is used. But when an output is tied to the state opposite to the logic of the inputs, you get a switch which will draw the max possible current constantly. The amount of this current is limited by the dimensions and materials of the internal transistors.

Lunetta circuits, which run at very slow audio and sub-audio rates, use very little current. Crank the clocks up a few hundred times and those chips would get too hot to touch and would eventually burn up if there are enough gates that are switching in the chip. This probably won't happen in a hex-inverter though. Still saving power one place give more to use elsewhere.

At one time I used to design CMOS DSP chips.

[/didactic]

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garcho



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PostPosted: Sat Oct 13, 2012 11:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks! Makes a lot of sense.
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garcho



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PostPosted: Sun Oct 14, 2012 12:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
[didactic and not necessarily directed at garcho]


I just want to add that the 2 reasons I visit this site are 1: to learn absolute basics; and 2: inspiration; so I hope folks like mosc don't feel like they have to tiptoe around the egos of hacks like me. Smile

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