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WIGGLING 'LITE' IN GUEST MODE

Splicer... (new mini-project)
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Splicer... (new mini-project)
J3RK
Edit:




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!

w00t
FetidEye
cool! i think i'm ready to build from schematic (if simple enough)

what do you mean by precision rectifiers?
J3RK
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.
J3RK
I had a few minutes between a couple of projects tonight, so...

w00t

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.

J3RK
Might as well use that last op amp. This is fun!

vurma
This looks quite useful! Keep us updated on that board will ya? ^^
J3RK
Your updated is ready This is fun! 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.

microfauna
Is this 12v or 15v? Could you put a Euro power header footprint on?
KNYST
Neat! Yes please w00t
CV input?
vurma
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.
BugBrand
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.
microfauna
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.
KNYST
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
catchpenny
does this work with CV signals?
BugBrand
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!
KNYST
^
ah, yes, thanks.

Will be following this with interest.
BugBrand
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!
BugBrand


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.
KNYST
applause
vurma
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?
BugBrand
LTSpice - free!
http://www.linear.com/designtools/software/

Only been learning it quite recently..
BugBrand
Wow (again)
The idea works in the nord g2 demo software too!
J3RK
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.
J3RK
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_) thumbs up applause
oberkorn
Quote:
If there's only a small amount of interest

interested! I'm in for two
amdagan
Nice idea this!
Wondering what would happen if you apply a CV directly to pins 3 and 5 of U1 ?
ashleym
Would there be any mileage in putting in some germanium diodes to mess the sound up a bit?
J3RK
The inverted output is really a lot less useful than a CV input, so I'll repurpose the last op amp for an input buffer for the CV signal. I can redraw this tonight after I wrap up a project for someone, and get the board changes in as well. (euro header, CV addition, etc.)

w00t

As to Germanium diodes... I'm not sure. I've never used them for anything personally. There's no reason you couldn't pop them in there, and see what happens.

Thanks again BugBrand! !
BugBrand
Germaniums wouldn't alter anything - you have pairs of diodes, rather than just a single, to overcome the inherent voltage drop of the diodes. (think I phrase that right).

CV to the non-inverting inputs? There could be something, but.. hard to say what - probably a dead end, to be honest. (ie. you'd have to add a fair bit - simple approaches are not good, frankly (having checked with sim))

The circuit is beautifully simple.
ashleym
....that means I will just have to get two boards and test against each other w00t w00t
J3RK
I'm thinking the CV input as is with a buffer would work, but if we want to sum in a manual control, that may need to be inverted as well. Which isn't a big problem, but it would flip which way it's modulated. At least that's the way I'd think to do it. (or could invert/reinvert the CV) Perhaps just a buffered CV input would be enough.

My FadeX crossfader circuit does a good job of doing VC and manually faded waveforms, and gives you control over the range of the fade/pan as well, so maybe I'll just stick to the CV input on the Splicer to keep it small and simple.

I'm sure there are still some Plan B splicers out and about too, if that manual control is really needed. It would be cool though, and I'm a consummate feature-creeper... Mr. Green If nothing else, I could put this in a third schematic on the first page of the thread.
CJ Miller
Neat! I love simple, useful modules like this. Hope I can get my $ problems sorted out to buy a few boards.
Kakihara
I would be down for 2 of those... Anyone will be in for euro faceplats making?
BugBrand
ashleym wrote:
....that means I will just have to get two boards and test against each other :party: :party:


Get two boards, of course - but, really, don't bother using up germaniums.

I was already convinced that changing to different diodes wouldn't do anything but then thought perhaps you could just change one in each pair - that'd surely do something? Well, real-life may beg to differ, but the simulations suggest if doesn't make the slightest bit of difference.

J3rk: dunno whether you even really need the buffer, to be honest. You could, if you wanted to use the 'standard' 100k input impedance, change all the 10ks to 100k (and the ones on the out summer can be the same too - basically, all identical) [oh, and put the R8 inside the loop]

You could buffer the CV input (but then, why not buffer the other inputs too?!) and then just have a manual control joining the opamp nodes in the same way as I added the CV input - just simple summing.

But, yeah, what to do with the extra opamp.. For audio, the output invert would be of minor use, but could be useful for CV work? Or put it down as an inverter, but 'un-committed'?
Dave Kendall
Hi.

Nice!
A tiny request - would it be possible to add extra pads for R5, R6, R7, R9 and R10 in parallel? That way pairs of 100K resistors could be used for each, instead of 49.9Ks, which are more expensive/harder to find. 100ks are used everywhere, and you can never have too many of them. They're like beer and munchies - stock up on them, so you never run out! smile
R7 and R9 might be tricky to get the pads in, but the others look relatively easy to add. Just a thought.....

cheers,
Dave
J3RK
Dave Kendall wrote:
Hi.

Nice!
A tiny request - would it be possible to add extra pads for R5, R6, R7, R9 and R10 in parallel? That way pairs of 100K resistors could be used for each, instead of 49.9Ks, which are more expensive/harder to find. 100ks are used everywhere, and you can never have too many of them. They're like beer and munchies - stock up on them, so you never run out! smile
R7 and R9 might be tricky to get the pads in, but the others look relatively easy to add. Just a thought.....

cheers,
Dave


You can actually just replace all of those with 47K or 100K or anything in that range. The ratios are what is important. You don't want to go too small though, so I'd stay in the 47K-100K range.
J3RK
BugBrand wrote:
J3rk: dunno whether you even really need the buffer, to be honest. You could, if you wanted to use the 'standard' 100k input impedance, change all the 10ks to 100k (and the ones on the out summer can be the same too - basically, all identical) [oh, and put the R8 inside the loop]


Putting R8 inside the loop would increase DC accuracy, but for audio use, doesn't that create some errors? I seem to remember some graph-plots from Dave Jones a while back that showed some interesting characteristics of doing that. I do this for my DC mixers, but not for AC devices.

Hmm, best to have a pair of these perhaps. One using a Linear Technology op amp and output resistor in the loop, and the other using an Analog Devices or Burr Brown and the resistor outside. w00t
Kent
I regret having sold my Plan B Wavesplicer. I'd like one of these for sure.
J3RK
It looks like there's some interest, so I'll incorporate some of these changes and ideas, adjust the layout, and see about getting some made.
J3RK
Here are the threads I was talking about:

https://www.muffwiggler.com/forum/viewtopic.php?t=81108&start=10&postd ays=0&postorder=asc&highlight=series+resistor+feedback

https://www.muffwiggler.com/forum/viewtopic.php?t=64576&start=0&postda ys=0&postorder=asc&highlight=series+resistor+feedback

Maybe the jumper/switch to optimize for either wouldn't be a bad idea. seriously, i just don't get it
J3RK
This one seems to work fairly well. I didn't really like how the pot behaved when summing it in via summing amp. It could be fixed with more parts, but I think just a CV will be more than sufficient for this. Basically it would fade it all the way to -500mV to 5V or 500mV to -5V on the other end. Interesting, but I'd like things to stay centered around DC0V for this. (and I'd like to keep it small) I also left in the inverting amp for the output. It could be useful for CV use.

I'm thinking about whether or not to add a switch or jumpers for the output resistors to move them in or out of the feedback patch. Some pads on the board would be simple enough to either switch or jumper. That way, one could build it with DC accurate op amps, and move them in the loop. Or build with audio, and move them out. I think this is how I will handle it. Just a couple of SIL headers.

Anyway, here is the updated schematic:

J3RK
New PCB layout is done. I will post it when I get a minute or two.

This is fun!
vurma
Well this whole thing escalated quickly. ^^

J3RK wrote:


I'm thinking about whether or not to add a switch or jumpers for the output resistors to move them in or out of the feedback patch. Some pads on the board would be simple enough to either switch or jumper. That way, one could build it with DC accurate op amps, and move them in the loop. Or build with audio, and move them out. I think this is how I will handle it. Just a couple of SIL headers.


Sound like a good idea. Adaptability is always preferable. So is feedback.
BugBrand
You know, I don't think it is worth bothering with jumper etc (not even sure why I brought up the resistor placement ha! But good digging on those 2 old threads - great info)

Last night I ordered a little test-board just to use up 1.5 sqr-inch spare for a proto board order. (haha - just realised I forgot to add the CV in to the final sum stage - idiot!!)
I put on a Mod depth dial and an Initial control - the initial control is to generate a -5 to +5 V offset. I actually used the spare opamp to generate a negative -10V ref (+10V from lm4040) and then sum the Initial via 200k resistors (ie. double the others)

Worth pointing out to people that this is kind of set for symmetrical waves, all of the same amplitude. Of course, waves often aren't precise bang-on 10V p-to-p (what's a few millivolts between friends?) so it is quite possible that in the real-world some small tweaks will be needed.
KNYST
voltage control Guinness ftw!
transistor logic
i love simple little projects like that. they help me getting back in diy .
lightworks
Hi!
Cool project!
Some time ago i did something similar for my own use, but with some simple LM13700 VCAs on each input. Might be a nice addition to your project also thumbs up
My ideia was to control the amplitude of each side of the wave with a joystick for FM stuff.


here is how it turned out:


All the best,
Ruben
J3RK
Nice! Yeah, I was thinking about adding VCAs before the inputs. I'll have to play around with that a bit. thumbs up
J3RK
I'm ordering prototypes for the basic boards tonight. As long as everything checks out, and I don't see what could really go wrong with this little guy, I'll be placing an order for Synthcube. These should be available in 3ish weeks. I would think.

As far as the excellent idea for VCAs by lightworks above...

My Mike Sims VCA board is the same 1"x3" size as the Splicer board. So two of those can be stacked right behind one of these for the same functionality. It's not as elegant as a single board, but I'm thinking some people won't want the VCAs, while others will. Myself included. I know some people can never have too many VCAs, but I think I've got something like 10 of them in my current system, so two more... I probably don't need right now. hehehe

I'll post more as soon as I get the protos back next week. I'll post a little audio from them as well.
iL
great project. i tryed to get one of those plan b splicers but with no success. like the idea of this thing. so i am in for some boards too!
monstrinho
One question; is this DC coupled? I'm just imagining the sorts of results you might get by plugging two sides of a DUSG into this. Or two LFOs or...
BugBrand
Yes (DC coupled)

Does DUSG produce Unipolar voltages? (ie. 0V to +10V)
If so then it ain't no use (without prior offsetting) as the inputs here need to be bipolar.
J3RK
Quick update. The prototypes will be back by the end of the week or beginning of next.

I believe the VCS can output an AC waveform, but I'm not sure about the DUSG. I haven't looked closely at that. You could always add a couple of differential amplifiers to this, with a switch.
Nantonos
Is there any particular reason why one CV is used for both halves? It seems from the schematic that these could easily be independent CV1 and CV2 (perhaps with the CV2 jack normalled to CV1). Or am I missing something?
yan6
I think i would be in for one of these
recompas
I'd be interested in at least one of these if you end up selling any boards - or are you planning on exclusively going through synthcube for this? Either is cool with me. Looks like a fun little module!
J3RK
They'll go through Synthcube mainly. I'll probably have a few on-hand as well.
J3RK
Nantonos wrote:
Is there any particular reason why one CV is used for both halves? It seems from the schematic that these could easily be independent CV1 and CV2 (perhaps with the CV2 jack normalled to CV1). Or am I missing something?


It works sort of like a crossfade the way it was added. So negative CVs fade one way, and positive fade the other. I'm not sure what there would be to gain by doing them separately, unless (as discussed previously) there was a VCA before each waveform input. However, for this particular board, I wanted to keep things simple, so it can be used as an addition to other projects in a supplemental way.

I have a VCA board that is the same size with the same mounting spec. Two of them could be stacked with this to allow VC attenuation of each input, plus the CV to fade between them. I don't know what this would look/sound like, at the moment, but could try it out a little bit when the PCBs get back to me to see if it's a useful configuration.

However, I also make a VC crossfader that's already available, that does this sort of thing already, so this is really for a different use.
Nantonos
Aha, that makes sense, thanks. (I had seen the earlier messages about input VCAs but not made the connection until you explained it).
J3RK
No problem! We'll see how it works out as soon as I get those boards out. I have a pair of the same VCAs that I can try it with, so we can see if it makes any significant difference, or makes things more fun that way. Mr. Green
J3RK
iL
sweet!

whats the vco part? it got two power ins?
J3RK
I just put multiple projects on one prototype board for testing. The Splicer is just the part below the line. The VCO is the new 4U version of the MirrorCore VCO. (there's a thread for that down a bit from this one)

w00t
J3RK
Splicing!

http://home.comcast.net/~r3cogniz3r/Splice.mp3

This is simply a sawtooth and a square from the same VCO being run into the inputs, and a sine wave LFO into the CV input.

The splices without modulation look perfect, one wave above 0V the other below 0V. The overall effect when modulated is very similar to a crossfader fading two waveforms (or any other VC Wave circuit for that matter.) At LFO rates, the spliced (with no modulation) waveforms make interesting modulation sources.

w00t
iL
i like it.

sounds like some ringmodulation or am modulation on fast duty. as modulation source i could imagine what that would mean.

nice.
apertureburn
very cool! I'd be interested in 2.

synthcube to have boards and panels?
J3RK
Yes, Synthcube will have these soon. I'll be placing the order today, and the boards should be in stock around 2 weeks later. I just got the IO list to Clarke for a dual Splicer panel. w00t
Rigo
J3RK wrote:
Yes, Synthcube will have these soon. I'll be placing the order today, and the boards should be in stock around 2 weeks later. I just got the IO list to Clarke for a dual Splicer panel. w00t

w00t indeed ... Will PCB and Panel only be available at Synthcube, or would Thonk stock them to ?
microfauna
Rigo wrote:

w00t indeed ... Will PCB and Panel only be available at Synthcube, or would Thonk stock them to ?


A complete kit would make a perfect DIY beginners project.
J3RK
I'm quite happy to send PCBs over to Thonk. Just need to arrange it.
Rigo
J3RK wrote:
I'm quite happy to send PCBs over to Thonk. Just need to arrange it.

My backlog hates you hihi
microtonal
This circuit falls into the diode based waveform splicer category. For a similar circuit look here:
http://electro-music.com/wiki/pmwiki.php?n=Schematics.WaveWiper
J3RK
Interesting, and very similar. I hadn't seen that one before. I was more basing mine off of my perceived function of the Plan B splicer. I never used one of the Plan Bs, so I set out to do something similar.

I've seen quite a few of Phobos' circuits before though, and quite like them. thumbs up
microtonal
The Phobos circuit was derived from Jim Patchell's "mother of all" Diode Waveshapers:

http://www.wavemakers-synth.com/motm/dws.html

http://electro-music.com/wiki/pmwiki.php?n=Schematics.DiodeWaveshaperB yJimPatchell
microtonal
Actually that second schematic link is not the "mother of all" diode wave shapers as shown in the MOTM build project, but a reduced circuit by Jim Patchell. The big circuit seems to no longer be available online.
J3RK
The production boards are in the mail on the way to Synthcube now. w00t
diablojoy
hmm ideal diode circuits are fun
played with the original jim patchell one and phobos version for a bit
which is really good
lol i got carried away with it though and went too far, still have some weird and ludicrous prototypes floating around somewhere.
J3RK
diablojoy wrote:
hmm ideal diode circuits are fun
played with the original jim patchell one and phobos version for a bit
which is really good
lol i got carried away with it though and went too far, still have some weird and ludicrous prototypes floating around somewhere.


Those are the best projects. I kind of do things both ways. In some cases, I simplify things down to just a core function, and see how small I can get it. In others, I just keep adding things until it gets a bit unwieldy and scale back a bit from there. Mr. Green

It's interesting that when I was searching around for this I didn't come across Jim's or Phobos' versions. I was probably using the wrong search terms or something. I remembered the Plan B one, and set out from there into the world of rectification. This is fun! It's definitely a fun and interesting area to explore. I have some other ideas I'd like to try. Like 90 degree splices, but haven't started working on any of that yet. I have a stack of things I need to get prototypes for first. Mr. Green
oberkorn
Quote:
The production boards are in the mail on the way to Synthcube now.

awesome! w00t
diablojoy
Quote:
It's definitely a fun and interesting area to explore. I have some other ideas I'd like to try. Like 90 degree splices, but haven't started working on any of that yet. I have a stack of things I need to get prototypes for first.

will look forward to what you come up with,
meanwhile attenuverters on the inputs are cool for this one
easy enough to add with foniks attenuverter chicklets, having said that 4 inputs and voltage control makes it nuts , and there i go again feature creep lol please ignore me that is not a serious request just an example of why i hardly ever finish anything fully - must be some sort of disease lol
J3RK
The way I've started managing that sickness, is to start on a panel layout part way into the design process. (right around where things start adding up a bit) If things don't make sense on the panel, I adjust the design a bit. Doesn't always work, but it has helped a few times. Either with adding more features, or taking away extraneous ones. Mr. Green
synthcube
We are awaiting the package anxiously smile
synthcube
the PCBs are available now for shipping via the webstore:

http://synthcube.com/cart/index.php?route=product/product&product_id=3 07

Bakeneko
Did anybody come up with a Euro panel or is it out with the trusty drill press?

regards
synthcube
We're doing one but not quite yet!
Bakeneko
synthcube wrote:
We're doing one but not quite yet!


Excellent.

cheers
lvoemachine
Here's a preview of my MU layout for the splicer! Let your ponytail down and splice it into a braid. I dare you.

I made this one a dual because it left too much panel space to just be a single module.

ashleym
J3RK wrote:
I'm quite happy to send PCBs over to Thonk. Just need to arrange it.


Any boards passing over the pond to Thonk or should I order from Synthcube for me in the UK? Thanks for finishing this, great to have a useful tone bender especially as I can have it on a panel with sockets only. Slim is sometimes best.
iL
finished my pcb!

fastest build ever. i wonder what the cv is doing and if its good to have a bipolar attenuverter before it?
or does it make more sense to attenuvert the wave input signals.

going to build this in a 4hp euro panel.

missed the marks for +/- on the supply header, but i guess the bottom ( on the picture of the pcb ) is -

no ground pad also so i hook it on the supply header for ground.
J3RK
iL wrote:
missed the marks for +/- on the supply header, but i guess the bottom ( on the picture of the pcb ) is -

no ground pad also so i hook it on the supply header for ground.


You are correct. Looking straight at the top of the board (where the text is right-side-up) the top pin is +, bottom is -. (same as MOTM, etc.) I'll get it added back on to the board layout for future runs. Sorry about that.

Since there are normal and inverted outputs, I don't know how important it would be to be able to invert the CV signal. However, a standard attenuator might be nice, if you don't have them elsewhere in your system.

Will also get a ground pad added. d'oh! I was basically using this as an add-on to a VCO in my own system, and this completely slipped my mind (since it was grounded via the rest of the VCO module. Dead Banana
iL
well i found the right +/- by looking at the elkos. at least i thought 50/50 chance and pluged in the power. nothing happens ( at least no smoke and the supply doesnt got angry ). hmmm.....

just asking for the cv because there might be space on the 4hp. maybe i can build it like this: having an extra attenuator in the system for cases i dont use the splicer. and i got plenty of the fonik cricklets attenuverter left.

so cv flips the w1+w2 symetry by voltage?

thanks!

J3RK wrote:

You are correct. Looking straight at the top of the board (where the text is right-side-up) the top pin is +, bottom is -. (same as MOTM, etc.) I'll get it added back on to the board layout for future runs. Sorry about that.

Since there are normal and inverted outputs, I don't know how important it would be to be able to invert the CV signal. However, a standard attenuator might be nice, if you don't have them elsewhere in your system.

Will also get a ground pad added. d'oh! I was basically using this as an add-on to a VCO in my own system, and this completely slipped my mind (since it was grounded via the rest of the VCO module. Dead Banana
iL
finished it up, front panel could be better but my printer does not work anymore.

used simple attaenuerter for the wave inputs and germanium diodes.

its really great for morphing lfos, two different coarsed lfos and the splice does strange morphings.


[/img]
waggles
Getting my parts order together and was wondering- does is matter what value I use for the bipolar caps, or can I just use whatever i've got sitting around?
J3RK
Those are just bypass caps. Some people like 10nF some like 100nF. I've used both, but have standardized on 100nF these days. The circuit will actually even work fine without any, but it's good practice to use them. Anything in that general range should do ok.
waggles
K sweet, thx
synthcube
The dotcom/mu panels are now in stock and available bundled with the PCBs.
Kits and assembled versions on the way....

http://synthcube.com/cart/index.php?route=product/category&path=99_103

lvoemachine
Is there a BOM for this yet?
lvoemachine


Tadahhhh!
synthcube
lovely!!!!!

here's the BOM... loaded on the webstore also, for the kits that are now available there.
raveboyy
So what is the main difference between a *classic* Xfader and this one?

Is this one basically the same thing only the quality is not so good for audio, but good enough for lower frequencies?

EDIT: Ignore this one, I already understand smile
snaper
Has somebody the schemo?
The picture on the first page is down :(
synthcube
here's the schematic
snaper
synthcube wrote:
here's the schematic

Thank you very much!!!
snaper
Last question, at some point I've lost in this thread.
So, is this OK for CVs?
Buchla implementation, so I have to know that should I put jacks or bananas to the wave inputs grin
locobitch
I just discovered the only module able to do this function and it was the Model 39 confused Now i'm in search for this module but in eurorack.
J3RK do you have some kits for sale in eurorack ?
synthcube
we offer the PCBs here, and have plans for a euro version...
locobitch
Some more questions.
It's possible to add some fade knob like on the model 39 ?
If yes anyone has a bom for the eurorack version ?
Ayab
Hi locobitch

The bom from the schematic supplied a few posts up from Synthcube -

Resistors: 6 x 100k, 6 x 49.9k, 2 x 330ohm
IC: 1 x TL074 op amp
3 x Diodes (1N4148?)
6 x jack sockets - Type of jacks should not matter if there is no panel pcb.

Not shown: Power header socket, couple of beads or resistors and 2 x 10uf (or choice) electrolytic capacitors on power input and couple of 100n ceramic capacitors to decouple the ic.
locobitch
Cool thanks Ayab grin Do you know if it's possible toi implement a turn knob like on the model 39 in parallel of the CV input ?
Ayab
A switched jack for the CV input with the switch connection normalled to +15V via a 100K resistor and the tip of the jack going to one outer connection of the pot, the other outer connection of the pot going to ground and the wiper of the pot going to the R11. 100K pot.

Then if the CV connection is not used the pot is a voltage divider and sends a voltage depending on the pot position and if a CV is connected the pot acts as an attenuator.

The attached picture makes this clearer.

Hope someone can please confirm that I am correct about this.
soup
The fader on mine wants wants +5V to -5V.

You could make 2 voltage sources and a dc mixer on a bit of stripboard but you'd double the size of the pcb.
Ayab
Aah ok I see oops thank you for pointing that out, soup.

I think your suggestion for a small dc mixer on stripboard is a good one.
locobitch
The idea is to have a pot to manually change the slice point and not having to use uniquely the cv in for that.
soup
The splice point can't be changed. The CV in (whether you add a knob or not) fades between the negative and positive sides of the waveform.
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