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 Forum index » DIY Hardware and Software
PCB adaptations of bits of the Buchla Music Easel
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delta32



Joined: Nov 03, 2008
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Location: Oxford, UK

PostPosted: Fri Jan 25, 2013 5:54 am    Post subject: Reply with quote  Mark this post and the followings unread

davemoog wrote:
Has anyone successfully built the envelope generator that works both in sustain mode and trig(transient) mode?


I managed to get transient/sustained functionality with regular gate signals on my build by replacing R101 with a 10nf cap.
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wackelpeter



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PostPosted: Fri Sep 16, 2016 6:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Sorry to dig out this really old thread...

As i'm currently building a cabinet that mostly features Buchla Clones i saved some Space for the Easel EG adaption by Aaron which seems to be pretty great to me (judging by his demo-video).
The Question regading this i have is: can this be set up to cycle with voltage control of the 3 envelope sections? I think of something somewhat similar to the Serge slopes... Well i noticed the Pulse out but i'm not sure if this is an end of cycle pulse output or a gate that's on as long as the whole 3 envelope steps are on...
If it's an end of cycle pulse then everything is fine and i have no further questions (i think).
If not i'm interested to hear if anyone had the same thought and tried to implement this and got success?
I guess the Serge slopes could give some good advice...
While looking at the schematics it seems to me like it is some kind of end of cycle output... but i'm not 100% sure

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thermionicjunky



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PostPosted: Sat Sep 17, 2016 8:12 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
Sorry to dig out this really old thread...

As i'm currently building a cabinet that mostly features Buchla Clones i saved some Space for the Easel EG adaption by Aaron which seems to be pretty great to me (judging by his demo-video).
The Question regading this i have is: can this be set up to cycle with voltage control of the 3 envelope sections? I think of something somewhat similar to the Serge slopes... Well i noticed the Pulse out but i'm not sure if this is an end of cycle pulse output or a gate that's on as long as the whole 3 envelope steps are on...
If it's an end of cycle pulse then everything is fine and i have no further questions (i think).
If not i'm interested to hear if anyone had the same thought and tried to implement this and got success?
I guess the Serge slopes could give some good advice...
While looking at the schematics it seems to me like it is some kind of end of cycle output... but i'm not 100% sure


Yes, it is an end of cycle pulse and it will loop the EG if it has been triggered. You'll need to either switch trigger sources during the envelope or add an OR gate to combine two trigger sources.
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wackelpeter



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PostPosted: Sat Sep 17, 2016 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you for the information... This seems to be an easy solution then... i will try it out...


Edit:

A few minutes ago i read that Don Buchla died at September 14. That's a heavy loss. R.I.P.

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wackelpeter



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PostPosted: Fri Sep 23, 2016 9:52 am    Post subject: Reply with quote  Mark this post and the followings unread

After i was stupid enough to try this Easel EG on stripboard i'm now at a point where i could need some help i guess...

Well it was a bloody mess soldering all these connections between the logic chips and avoiding flying bridges and keep them straight and in line...

Unfortunately it works not as supposed... I have now control over the attack with the attack knob... I have some kind of attack through the duration (sustain) knob and the decay knob works...

What i found out so far my control input (pin 6) of the 4066 (4016 in the original) get's no signal because the NOR that's feeding it has an one input a narrow pulse and the other is the inverted signal of this... So always at least one input is high which results into zero output...
Also the control input 12 of my switch which controls the decay section of the sustain phase get's no input.
there seems also to be at least one of each input channels getting a high signal...

i guess it has either something to do with the input shaping of the pulses or the pulse width within the circuit... i guess the pulse width of the narrower signal at the NOR gate must be a bit more narrow or delayed so that there'S a point when i have zero at both inputs to let the output of the NOR become high for a short time and fire the switch...

can anyone help me where to look closer within that circuit and maybe what to do to solve this?

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thermionicjunky



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PostPosted: Fri Sep 23, 2016 10:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Are you testing sustained or transient mode? Sustained mode has caused a lot of problems for people. Some have reported success using a specific Buchla-style pulse (a combination of trigger and gate) but my first attempt at replicating that didn't work out, so I hardwired mine for transient mode and added a gate-to-trigger converter. Transient mode is what makes this circuit unique anyway.
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wackelpeter



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PostPosted: Fri Sep 23, 2016 11:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you for the reply. I have tested first with sustained mode via 120k resistor and then transient mode... 390k didn't work but the method with a 10nF cap instead of this resistor works... tried some different cap values which got some working (triggering the EG) results down to 2,2nF...

From what i understand about the notes Aaron made on this circuit it has the attack phase the sustain phase which consist of two sections, one section feeding some CV to the attack mode and the other feeding some CV to the decay mode and at least the decay phase...
All through the 4016 (in my build a 4066) Switch... But my switch only get's a control signal at pin 5 and 13... the attack portion of the sustain phase and the decay phase... hence my sustain pot affects the attack only and the decay pot giving full range whilst attack doesn't do anything and the sustain pot has no effect to the decay phase...

The problem is at those NOR Gates controlling the switch...
There's always at least one input high... so i doesn't give out anything to control the 4066 switch which is then always closed...

say i have at input 8 of the 4001 this ___-___-__ i have at input 9
this ---_---_---

Same is with the gatter of the 4025 which controls pin 12 of the 4066...

Also read something about this 100pF cap (C11) which caused sometimes that the envelope holds with to long decay... didn't had this... but also played around with that value and removed it for a test...

checked all my soldering, drilled holes and connections twice at least, and couldn't spot any error (which does not mean that there is one, maybe) used 1% resistors for all...

then i had the sudden idea as i first got some mc1458 IC in ´the circuit that these because they are more vintage have bigger slopes in their outputs and changed them for tl072 but that would be too easy if that would be the problem... Sad
Also changing the LM3900 can't solve it...

I think i'll sleep a night over it and hopefully come up with a good idea... but if anyone still has some good advice, those must not come whilst sleeping, please let me know...


BTW. the output as it is using as a cycling thing doesn't work... when you have the decay or attack mode long enough there isn't any output pulse as the envelope doesn't fall below a certain level... but i guess there can be something modified... but first i want to have it working properly...

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thermionicjunky



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PostPosted: Sat Sep 24, 2016 7:59 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
...

then i had the sudden idea as i first got some mc1458 IC in ´the circuit that these because they are more vintage have bigger slopes in their outputs and changed them for tl072 but that would be too easy if that would be the problem... Sad
Also changing the LM3900 can't solve it...

I think i'll sleep a night over it and hopefully come up with a good idea... but if anyone still has some good advice, those must not come whilst sleeping, please let me know...


BTW. the output as it is using as a cycling thing doesn't work... when you have the decay or attack mode long enough there isn't any output pulse as the envelope doesn't fall below a certain level... but i guess there can be something modified... but first i want to have it working properly...


I built a dual module with Aaron's boards. I used TL072 opamps and 4016 switches. It loops if I trigger it and then connect the pulse out to the trigger in. This circuit does have some quirks with very long time settings. I have only tried it with fairly short settings.

I suspect your pulse source. I added two of the CGS gate-to-trigger circuits, which follow the capacitor with comparators, so the trigger amplitude is very high. I powered my comparators from the 13.5v supply and the resultant trigger works perfectly with the circuit as published.

I never had to dig any deeper into the circuit so I can't help with that level of detail.
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wackelpeter



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PostPosted: Sat Sep 24, 2016 10:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Many thanks for your advice.

Well i didn't came to the point to dive a bit deeper into this circuit... but yesterday late in the evening out of curiosity i desoldered the pin 9 from the NOR for the attack switch and voila the attack pot gave some difference to the envelope... well it wasn't attack... if i remember correctly it was more like some release time... but this should hab´ve something to do that the switch now is opened at the wrong timing settings...

With the trigger to gate converter you put after which cap? The 10nF before the LM3900 which is replacement for the 390K resistor or the 10nF that feeds a pulse to pin 2 of the NOR?

I've tried to trigger it with signals from my own gate to trigger converters (well Ken Stone's design) but directly before the input (120K or 10nF) which doesn't worked as i remember right...

I still have a strongly believe i could get this neat little cicruit working as suspected... Wink
Otherwise i would have a nice A/R generator and save 2 pots and panel space... Rolling Eyes Smile
Really like the somewhat sucking sound it produces when controlling a LPG at the end of the enevelope... doesn't simply fade out instead gives a nice swoosh or tschok to the sound Laughing

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thermionicjunky



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PostPosted: Sat Sep 24, 2016 11:21 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
...

With the trigger to gate converter you put after which cap? The 10nF before the LM3900 which is replacement for the 390K resistor or the 10nF that feeds a pulse to pin 2 of the NOR?

I've tried to trigger it with signals from my own gate to trigger converters (well Ken Stone's design) but directly before the input (120K or 10nF) which doesn't worked as i remember right...


I simply inserted the Ken Stone circuit between my gate input and the 390k (instead of merely replacing the resistor with a cap). I made no other changes and transient mode works. If it doesn't work for you, you have another problem. Perhaps the circuit doesn't like the improved specs of the 4066?
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wackelpeter



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PostPosted: Sun Sep 25, 2016 2:23 am    Post subject: Reply with quote  Mark this post and the followings unread

party!

hehe... got it working... cannot say for sure what it was... guess it must have been a very small solder bridge, so small i didn't saw it at all my inspections of the solder side with a magnifier or some small portions of flux... have scratched with a small srewdriver again (what i usually do after finishing soldering) between all my traces and voila what a wonder it works now...

thanks for your patience and i'm sorry that i haven't done this earlier... time to visit a ophtalmologist... Laughing

P.S.
had to lower the 100pF cap between pin9 of the 4066 and pin 6 of the NOR gates to 47pF to have an finite envelope at the longest settings... maybe 56pF would have worked too, but i had no time to wait a few hours... Very Happy

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thermionicjunky



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PostPosted: Mon Sep 26, 2016 9:08 am    Post subject: Reply with quote  Mark this post and the followings unread

wackelpeter wrote:
party!

hehe... got it working... cannot say for sure what it was... guess it must have been a very small solder bridge, so small i didn't saw it at all my inspections of the solder side with a magnifier or some small portions of flux... have scratched with a small srewdriver again (what i usually do after finishing soldering) between all my traces and voila what a wonder it works now...

thanks for your patience and i'm sorry that i haven't done this earlier... time to visit a ophtalmologist... Laughing

P.S.
had to lower the 100pF cap between pin9 of the 4066 and pin 6 of the NOR gates to 47pF to have an finite envelope at the longest settings... maybe 56pF would have worked too, but i had no time to wait a few hours... Very Happy


Great! Flux is definitely an issue on most prototyping boards (particularly around critical capacitors).

I swapped that cap today and I agree. The parameter ranges are much more usable now.
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wackelpeter



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PostPosted: Mon Sep 26, 2016 9:50 am    Post subject: Reply with quote  Mark this post and the followings unread

After i'm currently soldering my last Pulse Divider from Ken Stone i'm not sure if it was really flux... Noticed that on my brand new stripboard there are a lot of small particles between the traces... looked like copper... normally i scratch only between the lines where i have soldered and drilled to scratch of rests of solder, flux or copper and then rub it clean with a tooth brush...

hmmm... anyway it works and i'm really happy with it and will after the Pulse Divider (which is the last missing module in my previous cabinet so i can finally close the back wallet of it) build a second one for sure...

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wackelpeter



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PostPosted: Fri Oct 07, 2016 10:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Had a few hours of trouble shooting my latest build the Pulser from the Easel before i noticed i got the one pin of one of the diodes into the wrong row...
Then struggled with getting this thing into self cycling mode with the CD4001 used... but after some less attempts with less effort i had the idea to simply plug the Feedback (EOC pulse) into the Ken Stone Gate to trigger converter before going back to the switch and voila it works...
Seems as this is the best solution to get the needed shape and range of the EOC pulse for nice self cycling mode...

Because i wasn't sure if i needed the inverter or what else i could do with it i left a half of a MC1458 unused so far... now i could fix it easily on board...

P.S. forgot to mention that i had to exchange the input 390k resistor for pulse input R109 to a 10nF cap to get it triggering even with a trigger from a gate to trigger converter... even the 120k (sustained) where 390k should be transient mode didn't worked so far... Also have to play a bit with the enabling section... as my usual logical signals seem to low to enable it... maybe adding a pulldown resistor, boost that input to to some level that enables the output so that my other gear with a 5V gate will work and adding some further pieces to control this also with bipolar signals...
Will post an update when i got some satisfying solutions...

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wackelpeter



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PostPosted: Sat Oct 08, 2016 8:15 am    Post subject: Reply with quote  Mark this post and the followings unread

So finally i got everything fixed, or at least think i have all working as wished...

The non-cycling thing was fixed using the half of the OP-amp that was designated as inverter as a gate to trigger converter and switching it in-between the original feedback path...

The solution for the enabling function was to add a further OP-amp and use it as non-inverting amp to boost the normal 5V gate signals to a level where they turn the NOR gate on and off... also some diodes where added to do this funtion with bipolar signals too...
...and after some short testing sessions i can tell you it's worth the effort, to include this function as you can generate very complex pattern by using this function and also adding some VC of the rate...
BTW. when in self-cycling mode this function is only at the B-port available... if you turn off the 15V on input A it simply stops cycling and wouldn't start again from itself... and well both destinations are labelled wrong in the schematics... Enable A turns B off and enable B turns A off... nobody noticed that???

think i'm going along with this so i have 8x in/outs 2xpots, 3 switches and one LED on my front panel.
First i thought about using the other 2 switches but i couldn't find much sense of use for them, as i can switch whatever signal i have to switch on/off also with a VCA from one of the outputs...
Hmm... thinking about it, maybe some clock pulses can be switched on an off, more reasonable at longer pulse durations... don't know maybe a clock for a sequencer or divider with only counts further when the pulse is on or maybe an inverted version which counts as long as the pulse is off... not sure if those devices will accept such interrupted maybe randomly clock signals and if ti makes sense...

At least i'm happy with it and now got the missing parts to finish my 2 other Buchla VCO's and well fix my other LPG's as some of them are not as fast, sharp and quick turning off as my "master-prototype-most loved-favourite-LPG" which sounds amazing, especially at fast rates...
will have to select another few home-brewn Vactrols...
Also maybe want to note, that i tamed the resonance in VCF mode rapidly... increased the 51k resistor to ground at the resonance pot junction so that it starts ringing but don't start self oscillating and then clipping the sound and becoming very loud... think it sounds much more smoother this way...

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