buchla 281 clone - put your pcb order in quick.

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consumed
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buchla 281 clone - put your pcb order in quick.

Post by consumed » Thu Aug 07, 2008 9:47 am

http://www.buchla.com/historical/b200/2 ... rator.html

this circuit is a 4x AD with VC of both attack and decay (or release).
a clone pcb has been made for it and some initial reports from users are looking good.
EDIT: it is similar to the VCS in its flexibility but it does not track an incoming signal (so it cant be used for slew or envelope following, like the VCS)

so a second PCB run is being made up now.
if you're interested in this (or you think you will get into DIY someday and want to stash these),
then PM "topp" and let him know ASAP.
http://electro-music.com/forum/viewtopi ... &start=475

EDIT: the project page:
http://www.sdiy.org/toppobrillo/twoeightyone.html





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Last edited by consumed on Thu Jul 16, 2009 6:05 pm, edited 2 times in total.

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MrDys
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Post by MrDys » Thu Aug 07, 2008 11:30 am

So tempted. I like it because it's basically a VC Doepfer Quad AD (which I can't seem to shut up about) with a trapezoid generator thrown in. Anyone have a sense of the build difficulty on this?

Edit: Oh man, check out the envelope on the bottom. It's settled. I want this thing.

Image

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Post by Muff Wiggler » Thu Aug 07, 2008 12:12 pm

:hyper:

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Post by wetterberg » Thu Aug 07, 2008 12:20 pm

It's actually a VCAD, which the Quad AD isn't. And it's one AD per board, which I totally friggin' dig. And the range is higher - and since it is VC then it can be used as a VCO even. Me like.

And of course "peake" signed up for four, hehe.

The BOM looks a bit too massive for me to deal with right now. I think I'll pass. :-?

One thing I really like though - he has notes in the docs reg. running it under +-12v, so it could easily fit in a doepfer rig, albeit with some front plate magicck involved. that's pretty rad.

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consumed
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Post by consumed » Thu Aug 07, 2008 12:54 pm

i added a direct link to the project page in the first post.
im going to pick up four of these and build them in pairs (most likely).

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Post by flts » Thu Aug 07, 2008 12:57 pm

Wonder if I should pick up two boards for myself... So tempting, but I seem to have an endless supply of DIY projects without this already. *Looks at the Wogglebug PCB and parts lying on the workplace, waiting to be put together* :lol:

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Post by plord » Thu Aug 07, 2008 3:09 pm

OMG SWEET. :hail:

All y'all complaining about the unavailability of Banalogue VCS modules? This is that. Or a pair of them is most of a Wiard Envelator, minus the crossfader and plus the Quadrature function, which is different. Um, also plus the Peak function, whatever that is, and minus the inverted and spare positive outputs.

I just put in for 4 of them. Hell yes.

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Post by plord » Thu Aug 07, 2008 3:10 pm

Also, if you have Wogglebug parts lying around, sweet jesus, build yourself those and two of these and you have instant madness.

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Post by flts » Thu Aug 07, 2008 3:36 pm

Hehe, I was planning to build the Wogglebug today already (well, okay, just populate the PCB since I still need to make the panel and get some PCB-mount pots after that so it'll take a while to get it finished) but I basically ended up going through my shelves and throwing and giving tons of useless things away the whole day. Maybe tomorrow... SMD caps scare me a bit, but they aren't as small as I thought.

You have a good point with VCS though, I obviously wasn't thinking clearly and didn't really read carefully what the 281 does. Put in an order for two, it seems there aren't any really rare parts so no biggie.

edit: Building a pair of those would actually solve two problems I have - the lack of VCS availability and the lack of space for a Doepfer quad AD... :bang: Sometimes I'm so slow I amaze even myself.

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Post by wetterberg » Thu Aug 07, 2008 4:28 pm

but flts, this one *will* be enormous when fitted into a eurorack. It ge like 40HP, hehe.

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Post by wetterberg » Thu Aug 07, 2008 4:45 pm

as an aside, I am looking for a source for these knobs - these have the perfect modern-to-bakelite ratio for me.

Image

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Post by flts » Thu Aug 07, 2008 5:22 pm

wetterberg wrote:but flts, this one *will* be enormous when fitted into a eurorack. It ge like 40HP, hehe.
I don't think it'll be too huge if I build a dual instead of a quad (PMed an order for two boards earlier). Checking out the PCB measurements and amount of pots, it looks it could fit into something like 16-18 HP, at least if you squeeze it a bit.

We'll see, if worst comes to worst, space is always negotiable if the option is not being able to use cool shit you just built :lol:

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Post by wetterberg » Thu Aug 07, 2008 5:25 pm

the image above is a dual, not a quad. Turn that about sideways ;) At any rate it's killer, should be really useful!

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Post by flts » Thu Aug 07, 2008 5:54 pm

Yeah, I realized it's a dual. Still, I remain hopeful - at least until I have the boards and components in my hand and start measuring and emitting a continuous stream of swear words :hihi:

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Post by Luka » Thu Aug 07, 2008 5:55 pm

you can get the davis clone knobs at small bear.
the pcbs for this are tiny btw
this is another project in my backlog

canna wait till i get my shipment of components to build

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Post by wetterberg » Thu Aug 07, 2008 5:56 pm

think of it this way: If you make it big enough you can just slap rack ears on it and mount it outside the eurorack :party:

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Post by plord » Thu Aug 07, 2008 7:21 pm

You know what, I have to go check this, but I *think* the Envelator WILL copy the Quadrature function of the 281, you have to do something weird like short the two SQR outs together in cycle mode or something whack like that. I'll play with it and report :)

Still. $12 for boards, a bunch of common parts, and what, a $50 FPD panel and you got a VCS. OR if you're me, a $200 panel and you got a double-wide quad Envelator :)
Last edited by plord on Thu Aug 07, 2008 11:05 pm, edited 1 time in total.

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Post by wetterberg » Thu Aug 07, 2008 7:33 pm

consumed wrote:
wetterberg wrote:as an aside, I am looking for a source for these knobs - these have the perfect modern-to-bakelite ratio for me.
http://www.smallbearelec.com/Detail.bok?no=707
Thanks - even the knock-offs are a bit pricey in bulk... I may go with reans instead... hm.

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Post by futuresoundsystems » Sat Aug 09, 2008 2:39 pm

I just PMd Josh for a PCB... :hihi:
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Post by consumed » Sat Aug 09, 2008 4:50 pm

futuresoundsystems wrote:I just PMd Josh for a PCB... :hihi:
cool--but you might want to build them in pairs because of the enhanced functionality (i think you can configure for quadrature).

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Post by plord » Sat Aug 09, 2008 5:47 pm

Yes, absolutely, you want at least two of these :)

I have also confirmed that the Envelator CAN do the Quadrature function of the 281, but you have to patch it up with the included crossfader. Grant spelled out the details in a post to the Wiard list some time ago, here's the detail:
OK, one of the original functions of the SQR output on the Envelator was to act as mono-stable for making a gated ADSR envelope. That is if you have two Envelator modules, you can set up one as an ADSR and another as a monstable, this will give you a fixed gate time and allow you to "loop" an ADSR with the end pulse.

The polarity is wrong for using it in quadrature mode, SQR goes high and stays high as long as the Envelator is in the Attack portion of the envelope. For quadrature, you need the inverse.

You can use the cossfader on the bottom as a logic inverter to get the correct polarity. Here is how:

1. Put a dummy plug into the Mix2 input (disconnect Env 2 output)
2. Route a +10 volt signal to the Mix 1 input (a joystick all the way up
will work)
3. Route the Env 1 SQR signal to the Mix Mod input (mixture modulation)
4. Set the MixMod control to max and Mix control to min
5. Route the Mix output to the gate input of Env 2

Now Env 2 will start it's attack phase as soon as Env 1 completes it's attack phase, also called quadrature mode. Route Env 2 END pulse to Env 1 GATE input to make a quadrature LFO.

How does it work? When MixMod is at zero volts, Mix1 is routed to the Mix ouput, and it is at +10 volts. When MixMod is at +10 volts it is routing Mix2 to the Mix output, which is at zero volts - hence an inverter.

If you think about it, the Mix section on the Envelator can be used for logic functions, AND would be MixMod at +10 AND Mix2 at +10, otherwise the output is zero.

The input thresholds of gate inputs on the system are set to +1.5 volts so you can interface to +5 volts systems like Kenton and Roland rhythm boxes. So with the MIX control set to the center, with +10 volts at Mix1 OR Mix2, +5 volts will be output from the MIX output. Because the gate threshold is at +1.5 volts, it will behave like an OR gate.

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Post by Kwote » Sat Aug 09, 2008 6:37 pm

wow. see it's patches like that, that make me realize how shallow my patching knowledge is. i got a ton of experience to rack up.
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Post by plord » Sat Aug 09, 2008 6:47 pm

Me too. I've been working through that tips file I made up, but there can be a dozen uses for each tip, and I'm barely 10% through the list.

Grant does this all the time; posts a short tip that explains and outlines nine new things you never knew were there in the system. It's kind of awe-inspiring? I'm just sayin.

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Post by Kwote » Sat Aug 09, 2008 11:37 pm

fuck yeah it is. with the right knowledge you'll never get it all done.

said it before a thousand times. love this shit! :love:
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Post by consumed » Sat Aug 09, 2008 11:42 pm

there are many levels of ninja. and nobody knows how deep they go.

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