Splicer... (new mini-project)

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J3RK
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Splicer... (new mini-project)

Post by J3RK » Wed Nov 20, 2013 1:58 am

Edit: Image




Original Message:

I was thinking about doing a wave splicing sort of thing ala Plan B today. Not sure how Peter did it, so I whipped up my own. (which is probably pretty similar I would imagine)

It's basically two precision half-wave rectifiers (diodes flipped on one) going into a mixer. The rectifiers are inverting, so the phases swap places, and then the mixer (also being inverting) swaps them back to their original phases.

I'm going to whip up a small board for this, and maybe add a feature or three. It's a fairly simple design, made up of common components, so I'm happy to post the schematic once I lay it out as well. Right now I just have it sketched out on paper.

More soon!

:party:
Last edited by J3RK on Thu Nov 21, 2013 12:27 am, edited 2 times in total.
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FetidEye
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Post by FetidEye » Wed Nov 20, 2013 2:17 am

cool! i think i'm ready to build from schematic (if simple enough)

what do you mean by precision rectifiers?

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Post by J3RK » Wed Nov 20, 2013 2:23 am

FetidEye wrote:cool! i think i'm ready to build from schematic (if simple enough)

what do you mean by precision rectifiers?
This one should be absolutely no problem for you. One chip, a few resistors, and a few diodes.

By precision, I just me op-amp based rectifiers. (otherwise the waves could come out a little odd...) Nothing terribly special about them. That's just how I've seen them referred to while researching how I might do this.
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Post by J3RK » Wed Nov 20, 2013 2:24 am

I had a few minutes between a couple of projects tonight, so...

:party:

There's an unused op amp left on the TL074, so this could be used to make an inverted output. Pots could be swapped in on the feedback resistors for gain adjustment as well if desired.

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Post by J3RK » Wed Nov 20, 2013 3:05 am

Might as well use that last op amp. :cloud:

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Post by vurma » Wed Nov 20, 2013 3:09 am

This looks quite useful! Keep us updated on that board will ya? ^^
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Post by J3RK » Wed Nov 20, 2013 4:11 am

Your updated is ready :cloud: Now it's just a matter of seeing if someone wants to stock them. If there's only a small amount of interest, I could do a small run, but I don't have enough time to do a big one right now with all of the shipping etc.

It's ready to place an order though once I have an idea of how to approach it. It will be a very inexpensive board. Could also be fun with a pair of VCAs maybe to have voltage control over the inputs. Not sure what that would look like, but I may try it out.

More as soon as I figure out what to do with it.

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Post by microfauna » Wed Nov 20, 2013 4:28 am

Is this 12v or 15v? Could you put a Euro power header footprint on?

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Post by KNYST » Wed Nov 20, 2013 4:39 am

Neat! Yes please :party:
CV input?
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Post by vurma » Wed Nov 20, 2013 4:59 am

Awesome!
microfauna wrote:Is this 12v or 15v? Could you put a Euro power header footprint on?
Looking at the PCB, it seems like its already taken care of.
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Post by BugBrand » Wed Nov 20, 2013 5:02 am

It shouldn't matter 12V/15V -- it is just opamps doing their thing..

CV input? Perhaps simply adding further waves to the input summing nodes - ie. add further resistors like R3 and R4

That extra opamp could, perhaps, be used for CV/Modulation input? Haven't tried, but could it be interesting to have one Mod input going to both input sides, but have one inverted (ie. through that spare opamp) - should be easy to try on your software.

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Post by microfauna » Wed Nov 20, 2013 5:04 am

vurma wrote:Awesome!
microfauna wrote:Is this 12v or 15v? Could you put a Euro power header footprint on?
Looking at the PCB, it seems like its already taken care of.
I see the header shape, but not the solder points.

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Post by KNYST » Wed Nov 20, 2013 5:38 am

I have a M39. I'd say the VC input on it is essential. Morphing, fading between the input waves...
When nothing is plugged in into the VC input, one can use the pot to sweep between the two input signals.

For anyone interested, read more here: http://www.modulargrid.net/e/plan-b-model-39
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Post by catchpenny » Wed Nov 20, 2013 5:44 am

does this work with CV signals?

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Post by BugBrand » Wed Nov 20, 2013 5:48 am

CV/DC - yes (well, presumably..)

Knyst - I think.. that my suggestion for the final 1/4 opamp with one CV input going inverted & non-inverted could well do that cross-fading. It makes sense in my head, at least.. Oh - or maybe you DON't want to invert the CV. Hmm. Simulation needed!

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Post by KNYST » Wed Nov 20, 2013 6:26 am

^
ah, yes, thanks.

Will be following this with interest.
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Post by BugBrand » Wed Nov 20, 2013 6:43 am

AHHH!

Did a quick sim (I'm not very good with such things actually)

You just need to add the CV (non-inverted) to BOTH nodes
but then ALSO into the summing node after the half-wave-rectifiers.

Oooh!

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Post by BugBrand » Wed Nov 20, 2013 6:49 am

Image

OK - wow, so that's kind of like a cross-fader...

Here I have a 10Hz and 50Hz sine going in
0.1Hz sine for modulation.

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Post by KNYST » Wed Nov 20, 2013 7:00 am

:yay:
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Post by vurma » Wed Nov 20, 2013 7:12 am

BugBrand wrote:AHHH!

Did a quick sim (I'm not very good with such things actually)

You just need to add the CV (non-inverted) to BOTH nodes
but then ALSO into the summing node after the half-wave-rectifiers.

Oooh!
Haha! Sounds like some good hacking is going on over there. What software are you using for the simulation?
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Post by BugBrand » Wed Nov 20, 2013 7:27 am

LTSpice - free!
http://www.linear.com/designtools/software/

Only been learning it quite recently..

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Post by BugBrand » Wed Nov 20, 2013 7:47 am

Wow (again)
The idea works in the nord g2 demo software too!
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Post by J3RK » Wed Nov 20, 2013 11:25 am

microfauna wrote:Is this 12v or 15v? Could you put a Euro power header footprint on?
It will run on either with no changes. Also, yes, a Euro header would be quite easy to add, and I'll definitely add it.
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Post by J3RK » Wed Nov 20, 2013 11:29 am

BugBrand wrote:AHHH!

Did a quick sim (I'm not very good with such things actually)

You just need to add the CV (non-inverted) to BOTH nodes
but then ALSO into the summing node after the half-wave-rectifiers.

Oooh!
Nice! That's very cool! I was going to suggest that I add a VCA in front of each input, (which could still happen,) but your way is much smaller! Thanks for looking at this. 8_) :tu: :yay:
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Post by oberkorn » Wed Nov 20, 2013 12:23 pm

If there's only a small amount of interest
interested! I'm in for two
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