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Buchla Source of Uncertainty 266
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
Location: NYC

PostPosted: Fri Feb 20, 2009 11:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

vtl5c3 wrote:
Hiya,

The original did not have stepped outputs. That's one of the mods that Scott showed to me. The original didn't have a noisy triangle output either.

R.

ericcoleridge wrote:
VTL5C3, or anyone,

Just noticed, on the FRV section of the 266 SOU, there are only 2 outputs.

Was there no FRV Step output on the original, or maybe one side outputs just FRV and the other side just Stepped FRV?


Yeah, it really is a great mod. I'm reproducing the original front panel, so I may just use one of the stepped outs as the second FRV out. But then, when it's paired with the stored random voltage, S+H, etc, perhaps it won't seem as necessary. We'll see.
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funkyfarm



Joined: Jan 21, 2007
Posts: 583
Location: France
Audio files: 3

PostPosted: Fri Feb 20, 2009 11:36 pm    Post subject:
Subject description: RV
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ericcoleridge wrote:

LetterBeacon wrote:

Board 1 - 266_1 - Quantized Random Voltages

The first output adds up a mix of all equal quantized voltages (all 1.2V, for instance). The second output adds up a mix of different quantized voltages (for instance: 1.2V, 2.4V, 4.8V, 9.6, etc--all in related ratio)


Damn !?

So I want a 1 V/Oct QRV module Very Happy
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
Location: NYC

PostPosted: Fri Feb 20, 2009 11:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK, I have a new problem (sorry Confused ):

I have board 4 all populated and powered. I've looked at all of the chip and diode orientations, the board looks clean--no bridges or shorts, all chips are getting power.

But I don't think anything is working. Everything is passing signal-- but the slew won't slew very much- if at all.

The sample and hold seems to be more just following the input voltage, then going to ground on gate. When I input a noise, it more less just outputs a garbled noise.

I should say first that I did not populate any of the LED cicuitry. But, it doesn't seem like this should have any effect-- and indeed, it's marked as 'optional' in the notes.

So, my next suspicion is the trim pot orientation. I'm sure this could be effecting the Slew, but not sure why it would have any effect on the S+H.

Could anyone make a suggestion on where I could start looking for problems on eirther the slew or S+H, or both?
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Scott Stites
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Joined: Dec 23, 2005
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Audio files: 96

PostPosted: Sat Feb 21, 2009 12:03 am    Post subject: Reply with quote  Mark this post and the followings unread

This is such a cool project! One thing that I found really nice was to rig a trigger output from the 556 (I actually used a 7556 in my experiments) that drives the FRV. That was nice, because it was synchronized with the stepped output of the FRV, and its rate is voltage controlled to boot (via the Probability of Change control input). It provides an additional opportunity for the SOU to "feed on itself" - for example, you can patch it into the pulse input of the S&H or one of the pulsed random voltages. Or is that already in? Guess I better check. Embarassed

I dredged this sample up off my old site - here's the description on the site:

Quote:
And finally, this is a sample of the RFV doing what it does best - it's controlling a VCO, the DSC2000, and the 2040 filter. There's quite a bit of overdubbing in this sample - check it out if you like 'weird' =0). The creepy intro timing is all determined by the RFV - the EG is controlled by the trigger out of the module, and the smooth output is controlling the 'probability of change', which controls the clock frequency and smooth lag time.


I had the mistaken habit back in those days of writing "RFV" instead of "FRV" Laughing It's the piece called "Landing on a Different Planet in the '50's", in case you've already heard it.

Cheerios,
Scott


rfv_sam_short2.mp3
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
Location: NYC

PostPosted: Sat Feb 21, 2009 1:07 am    Post subject:
Subject description: RV
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funkyfarm wrote:
ericcoleridge wrote:

LetterBeacon wrote:

Board 1 - 266_1 - Quantized Random Voltages

The first output adds up a mix of all equal quantized voltages (all 1.2V, for instance). The second output adds up a mix of different quantized voltages (for instance: 1.2V, 2.4V, 4.8V, 9.6, etc--all in related ratio)


Damn !?

So I want a 1 V/Oct QRV module Very Happy


If you could figure out the right values on the outputs of the shift register, you change the voltage levels to standard volt/octave quantization. Or you could get the Doepfer version which is re-designed for volt/octave.
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ericcoleridge



Joined: Jan 16, 2007
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PostPosted: Sat Feb 21, 2009 1:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Scott Stites wrote:
It's the piece called "Landing on a Different Planet in the '50's", in case you've already heard it.


What a fantastic sample. Thanks for posting this.
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funkyfarm



Joined: Jan 21, 2007
Posts: 583
Location: France
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PostPosted: Sat Feb 21, 2009 11:49 am    Post subject:
Subject description: well-tempered sou
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ericcoleridge wrote:

funkyfarm wrote:


So I want a 1 V/Oct QRV module Very Happy


If you could figure out the right values on the outputs of the shift register, you change the voltage levels to standard volt/octave quantization. Or you could get the Doepfer version which is re-designed for volt/octave.


So i'll vamp dieter's work Laughing

I guess B266-2 SRV module would also suffer from a strange 1,2V quantification.
Even with a standard 1/12V quantiser on output, it won't lead to the same melodies as in a Buchla 200 system...and you insult Don's talent Smile


PS : if you can have QRV module working, I think it would not be so hard to test different points on pcb, find 1,2V and its multiples, maybe check which voltage supply is involved, and then have some really simple maths...
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funkyfarm



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PostPosted: Sat Feb 21, 2009 12:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Scott Stites wrote:


I had the mistaken habit back in those days of writing "RFV" instead of "FRV" Laughing It's the piece called "Landing on a Different Planet in the '50's"


Cool sample !

(forget what I've just said before, there is no insult)
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
Location: NYC

PostPosted: Sun Feb 22, 2009 10:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

ericcoleridge wrote:

Could anyone make a suggestion on where I could start looking for problems on eirther the slew or S+H, or both?


I changed out the trim pot-- but to no avail! I'm not sure where to go next with this circuit. Are there any points where I could test for a specific level, anything to give me some idea of what might be in error here?
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vtl5c3



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Posts: 425
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PostPosted: Mon Feb 23, 2009 3:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Eric,

The fact that the slew circuit isn't working shouldn't affect the rest of the board, unless there's something melting down and drawing the current away from everything else.

Focussing on the S&H circuit - first of all, how hot are your pulses? 5V or higher?

Are you seeing pulses at the pulse outputs?

What are you seeing at pins 7&8 of the LF398s?

How about pins 6&12 of the CD4016?

Romeo

ericcoleridge wrote:
ericcoleridge wrote:

Could anyone make a suggestion on where I could start looking for problems on eirther the slew or S+H, or both?


I changed out the trim pot-- but to no avail! I'm not sure where to go next with this circuit. Are there any points where I could test for a specific level, anything to give me some idea of what might be in error here?
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ericcoleridge



Joined: Jan 16, 2007
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PostPosted: Mon Feb 23, 2009 3:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'll check all of these things. Thanks-- sorry for all of the trouble. Perhaps when others build these circuits- these notes will be useful.
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
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PostPosted: Mon Feb 23, 2009 10:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

vtl5c3 wrote:

The fact that the slew circuit isn't working shouldn't affect the rest of the board, unless there's something melting down and drawing the current away from everything else.


vtl5c3 wrote:

Focussing on the S&H circuit - first of all, how hot are your pulses? 5V or higher?


Yes 5v or higher from an Arp Gate out, and an LFO trig out. Curiously, when I touch the lead of my meter to the clock input, I get a little response from the sample and hold-- rather than just garbled noise from the noise at the S+H input. Not sure what this indicates-- if anything.

vtl5c3 wrote:

Are you seeing pulses at the pulse outputs?


Yes, 10v or more pulse output.

vtl5c3 wrote:

What are you seeing at pins 7&8 of the LF398s?


about 2v at pin 7 and 3v to 4v at pin 8.

vtl5c3 wrote:

How about pins 6&12 of the CD4016?


I'm getting a constant 14v at pin 6, and nothing at pin 12 (unless it's negative, in which case I can't read it on my analog meter).

I just realized something else-- my decoupling .01uf caps were pulls. Is it possible that if any of them are bad-- that one or more could be drawing out current to ground--and causing the circuit to malfunction. Is this a dumb question? Should I replace them all? Is it safe to run the circuit without these decoupling caps?
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LetterBeacon



Joined: Mar 18, 2008
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PostPosted: Thu Feb 26, 2009 3:06 am    Post subject: Reply with quote  Mark this post and the followings unread

ericcoleridge wrote:
Perhaps when others build these circuits- these notes will be useful.

I'm certainly following this thread with interest.

Does anyone know where I can find the 1N5228 zener diodes in the UK or Europe? I can't find a source at all. Could I perhaps use a substitute?
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vtl5c3



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PostPosted: Thu Feb 26, 2009 9:16 am    Post subject: Reply with quote  Mark this post and the followings unread

That's simply a 3.9 V Zener diode. There others that would work, such as the 1N4730 and 1N748.

LetterBeacon wrote:
ericcoleridge wrote:
Perhaps when others build these circuits- these notes will be useful.

I'm certainly following this thread with interest.

Does anyone know where I can find the 1N5228 zener diodes in the UK or Europe? I can't find a source at all. Could I perhaps use a substitute?
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LetterBeacon



Joined: Mar 18, 2008
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PostPosted: Thu Feb 26, 2009 9:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Ah I see, so any zener diode with a voltage rating of 3.9 will work?
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ericcoleridge



Joined: Jan 16, 2007
Posts: 889
Location: NYC

PostPosted: Fri Feb 27, 2009 7:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

I sent out MM5837 noise ICs today to everyone with a US address who requested one. I have one IC left for anyone who wants.
EDIT: All the ICs have gone out now.

Last edited by ericcoleridge on Wed Mar 04, 2009 10:28 pm; edited 1 time in total
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forbin



Joined: Jan 29, 2009
Posts: 120
Location: Fremantle, Australia

PostPosted: Wed Mar 04, 2009 4:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well i have finished the SRV board (board #2) and have found a couple of minor tweeks are required for all to be well.

* pin 4 of the TL074 (left hand one on overlay) needs to be connected to power
* pin 9 of the 4015 (center CMOS) needs to be connected to the clock line (same as the pin 9 of the other 4015)
* the diode bridge pull-up to +15 needs to be moved to the other end of the diode bridge

All the changes are very short bridges and can be easily done.

Other considerations:

I found that I had to boost up the decoupling as I was getting a lot of noise and glitches. I put some extra 1uF/10uF tantalum's around the place which fixed it up. I also had some 10V references lying around and I found that they made a significantly cleaner 10V source for the CMOS devices.

Does work well now and I am very pleased with the results. Thanks again to vc3tl again for the board layout!

See http://forbinthesynthesizer.blogspot.com/ for some CRO plots and other pix -- i have some other SPICE simulations and a couple of other suggestions for component tweeks that I am still experimenting with, but will post when they have solidified...
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ericcoleridge



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PostPosted: Wed Mar 04, 2009 5:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great blog. Thanks for posting your results. I'll keep watching for updates.
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vtl5c3



Joined: Sep 08, 2006
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PostPosted: Wed Mar 04, 2009 7:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Forbin,

Thanks for the feedback. FunkyFarm had pointed out the missing trace on the TL074. I fixed that and the trace on the CD4015. The posted layouts have been updated with those fixes today.

Sorry to hear about the noise and glitches. I haven't noticed any on mine, but maybe I haven't looked at it as closely as you.

I'll check out your blog a bit more closely later on. I will say that it's nice to see people etching boards with my layouts. Makes me feel all warm and fuzzy inside! Very Happy

forbin wrote:
Well i have finished the SRV board (board #2) and have found a couple of minor tweeks are required for all to be well.

* pin 4 of the TL074 (left hand one on overlay) needs to be connected to power
* pin 9 of the 4015 (center CMOS) needs to be connected to the clock line (same as the pin 9 of the other 4015)
* the diode bridge pull-up to +15 needs to be moved to the other end of the diode bridge

All the changes are very short bridges and can be easily done.

Other considerations:

I found that I had to boost up the decoupling as I was getting a lot of noise and glitches. I put some extra 1uF/10uF tantalum's around the place which fixed it up. I also had some 10V references lying around and I found that they made a significantly cleaner 10V source for the CMOS devices.

Does work well now and I am very pleased with the results. Thanks again to vc3tl again for the board layout!

See http://forbinthesynthesizer.blogspot.com/ for some CRO plots and other pix -- i have some other SPICE simulations and a couple of other suggestions for component tweeks that I am still experimenting with, but will post when they have solidified...
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forbin



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PostPosted: Wed Mar 04, 2009 8:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi vtl5c3

The board layouts are fantastic and i am positive that i wouldn't have done anything if you hadn't laid them out! I did spend a lot of time analyzing some of the Buchula stuff about 4 or 5 years ago with the plan to making some boards, but it rapidly came to naught.

The problems that i saw was that the output would go into oscillation on largish transients. Unfortunately i didn't photograph it as i didn't have the camera with me at the time!

I am onto board #1 now -- will let you know how that goes.
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funkyfarm



Joined: Jan 21, 2007
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PostPosted: Thu Mar 05, 2009 4:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

266-2

STORE RANDOM VOLTAGE


Hi,

looking at the pcb layout, the two led drivers don"t look the same ; i guess one 100ohm resistor is missing for CV 2...or maybe there is one unwanted resistor, that put base signal to ground (via only 100ohm ?).

Very Happy

why not putting 100nf all the way for decoupling, instead of 10nF ?
Two 10/22uF are perhaps missing with ferride beads...

Looking at Scott's schematic, the pot and cv control circuitry only affect CV 2 output, right ?
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vtl5c3



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PostPosted: Thu Mar 05, 2009 4:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

Bwahahahaaaa! You guys are finding all sorts of mistakes.

The 100ohm resistor from base to ground on the CV1 LED should not be there. Only from Emitter to ground.

You can definitely use .1 uF caps instead of .01 for decoupling. I tried to make extra pads to accomodate two sizes of caps.

And yes, I forgot the electrolytic/tant caps after the ferrite beads. I'll make corrections and post another update.

funkyfarm wrote:
266-2

STORE RANDOM VOLTAGE


Hi,

looking at the pcb layout, the two led drivers don"t look the same ; i guess one 100ohm resistor is missing for CV 2...or maybe there is one unwanted resistor, that put base signal to ground (via only 100ohm ?).

Very Happy

why not putting 100nf all the way for decoupling, instead of 10nF ?
Two 10/22uF are perhaps missing with ferride beads...

Looking at Scott's schematic, the pot and cv control circuitry only affect CV 2 output, right ?
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funkyfarm



Joined: Jan 21, 2007
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PostPosted: Thu Mar 05, 2009 5:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

funkyfarm wrote:
266-2

STORE RANDOM VOLTAGE


Looking at Scott's schematic, the pot and cv control circuitry only affect CV 2 output, right ?


Very Happy

I hardly understand the original serigraphy...

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



Joined: Jan 21, 2007
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PostPosted: Mon Mar 09, 2009 3:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

Doepfer serigraphy is simplier for me Cool

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

POT is only for SRV 2 output....

i guess cv too.
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funkyfarm



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PostPosted: Tue Mar 10, 2009 1:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

266-3

FLUCTUATING RANDOM VOLTAGE
Stepped outputs - dual input

I've understood that two sockets should be added : two "stepped" versions of main FRV1 and FRV2 outputs.

But it is mentionned here or there that ou could also add a NC socket input for each circuits. Normally connected to digital noise source (more or less 11V), it allows user to feed the module with standard noise source (is there any interest ?) or wogglebug signals...

If so, any diode or resistor protection is needed ? see "a" point on this schematic :

http://www.musicsynthesizer.com/Buchla/266-3.jpg


266-4

SAMPLE & HOLD
separate inputs

Is there any use in adding separate pulse inputs and cv inputs for both S&H circuitry ?
separate pulse just requires cutting a trace ; dual cv in requires another R65 10K resistor.

http://www.musicsynthesizer.com/Buchla/266-4.jpg
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