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 Forum index » DIY Hardware and Software » fonik's place
Advanced Sync for the VC Master Clock
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diablojoy



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PostPosted: Sat Mar 19, 2011 12:17 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok tried mathias suggestion for sync but did not have much luck at getting a good solid sync
so next i tried using a cd4016 switch to dump C2 to ground. this had more promising results sort of but also required the use of a buffer on the master clock output as the cd4016 logic input had a rather nasty effect on the clock pulse shape and i will still wanted to use that output as per normal

I did manage to acheive a hard sync over almost the full range to the clock designated as master but only under certain conditions
a] the synced clock's rate pot must be set to max rate
b] PW pot on the synced clock had to be within a small range around 60 - 70%
with sync acheived the pulse width of the synced clock can be controlled from the master clock however note there is some strange things to be gained

odd bits : if the master clock's pulse width is at max the synced clock will
evolve and become quite odd over a short period of time [some 20 secs] since the clocks PW can be voltage controlled this could be interesting

more odd bits : if you vary the synced clocks PW slightly around the area of 60-70% you either start to lose clock pulses or gain them however get too close to 90% and the clock output goes high and remains there go below about 50% and the clock output goes low and stays there
a few more odd happenings with slightly dropping the synced clocks rate from max as well

will check out using a cd4016 to stop certain clock pulses from reaching the output via JP1 -JP2 next
cheers
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diablojoy



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PostPosted: Sat Mar 19, 2011 6:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

considered yesterdays results overnight
I had doubts about getting such a hard sync from C2
or the other odd effects i noted and rechecked everything this morning
found the cd4016 was not at gnd on vss pin in fact the breadboard was at fault gnd was open at the first point [bad socket] so worked around that and...
what i expected occurred the sync is much softer
sync is still acheivable but you do need to get closer with the rate pots before a lock is noticeable and you can get the odd extra pulse which can't be seen just by the led's still it is very interesting
retried removing the gnd from breadboard and it emulated yesterdays
result exactly which is also interesting not sure why it has this effect yet
but i gotta say i like it and it does not seem to be causing any real drama's
perhaps a bonus by accident so it seems! will do more testing as i would like to understand this better as near as i can figure at the minute
with vss floating the switch is sending out a positive offset pulse into C2
overcoming its normal charge / discharge cycle though i am far from certain on this but it may explain the strange PW behaviour
I also tried out clocking a cd4016 across JP1/JP2 to mask clock pulses
works quite well and also slightly differently depending if vss pin of cd4016 is at gnd or not . Had to try it Wink
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diablojoy



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PostPosted: Sun Mar 20, 2011 12:34 am    Post subject: Reply with quote  Mark this post and the followings unread

was correct about positive offset pulse with the floating ground on cd4016
tried not using the cd4016 and going direct from output of a buffer to Q3 collector side of C2 with the square pulse from master clock result
total sync with no artifacts master controls both speed and pulse width
the synced clocks controls have no effect and so really not a good result actually. better to use mathias's suggested master / slave switches for this

so back to the original way i suggested to hook up the cd4016 i think, actually across C2 and not to ground which I just now retried. it is giving a good sync now that the cd4016 is grounded properly and can get some good double , triple or more pulse groups with careful adjusting Very Happy yay!
will now start working out a PNP board for a dual or quad clock module
daughter board with the slightly soft clock sync and pulse blanking
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brother303



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PostPosted: Sun Mar 20, 2011 4:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

diablojoy wrote:
...will now start working out a PNP board for a dual or quad clock module
daughter board with the slightly soft clock sync and pulse blanking


Sounds good! Very Happy

I wish my knowledge about electronics would be as good as yours... Embarassed

A quad addon pcb would be great!

Best regards
Greg
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diablojoy



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PostPosted: Sun Mar 20, 2011 1:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I wish my knowledge about electronics would be as good as yours...


thanks but not so good really, i wish it were better, always more to learn.

the buffer is no longer required as that bad ground was also the cause
of the pulse degradation
so will just be 2 x cd4016 and a few components for a quad unit
panel space will get tight though
16 pots
4 leds
24 jacks -1 x rate CV, 1 x PWM, 2 x out - i think i can get away with that as is , 1 x sync in jack and 1 x pulse blank in jack per cct
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brother303



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PostPosted: Mon Mar 21, 2011 3:56 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

do you start a run of pcbs or provide the layouts for homebrewing?

And some little wiring-instructions would be great,too... Wink

Please
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fonik



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PostPosted: Mon Mar 21, 2011 7:09 am    Post subject: Reply with quote  Mark this post and the followings unread

great work, diablopoy!

i hope i understood everything you said:
so you just bypass the cap using a switch?
is this hardsync?
what do you mean by softsync then?

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diablojoy



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PostPosted: Mon Mar 21, 2011 2:11 pm    Post subject: Reply with quote  Mark this post and the followings unread

the sync can be hard or not depending on rate pot settings and pulse width
settings on both slave and master .
eg with a slow master clock the slave can be adjusted to be exactly in sync
with the master then by increasing the master rate the slave will also follow exactly however if you just increase the slave rate you still get a wider synced pulse but you also get extra smaller pulses from the slave. the pulse widths remain adjustable to a point though at higher settings it becomes a solid high output on the slave [care must be exercised here]
the synced pulse appears to be some what wider in pulse width than the one coming from the master with narrow pulses coming after it [accent?] depending on the rate set on the slave the pulse width pots on both slave and master can also be used for yet more variation eg i could see some evidence of syncopation with some settings getting groups of pulses in two's or three's
this is all viewed on a scope by the way so setting it up in a real life use
just by the led indicators would be more difficult but i think you should be able to hear or see the effect quite well when driving a sequencer by the way it steps
i have yet to check this though [next weekend i hope]
then there is the pulse blanking as well which when clocked by another slower clock or lfo effectively removes pulses from the output at a determinable rate which can also provide good syncopation or stop / start without effecting clock timing eg-say on for 8 pulses and off for 4 pulses
depending on rate and pulse width of the clock or lfo sent in the blanking jack [logic in of the cd4016 across JP!/JP2]
i must say if the results i saw on the scope translate in use this is orsm Very Happy
cheers
denis
edit : I have no real good way of displaying any scope shots
but i think if you try bread boarding this yourself it may be best
very simple cct- yes one section of CD4016 straight across C2. I used those extra pads you had the foresight to provide and the output of the master clock directly in to the logic pin of that section of the CD4016
nothing could simpler than that. dont forget to ground the other sections of the cd4016 use another section of the CD4016 across the JP1/JP2 pins to check out the blanking cct idea. I did it exactly this way with the same master running both logic ins as i only have built 2 boards Embarassed so far quite entertaining Laughing

Last edited by diablojoy on Mon Mar 21, 2011 2:35 pm; edited 1 time in total
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fonik



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PostPosted: Mon Mar 21, 2011 2:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

i see. sounds awesome and goes way beyond a "Master"-Clock Very Happy

BTW did you take a look at the ramp TP when synced? i am asking, because this is the main point of applying sync, i would believe: you want to utilize the comparators in a gainful way...

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diablojoy



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PostPosted: Mon Mar 21, 2011 2:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
BTW did you take a look at the ramp TP when synced?


no but i still have it on my breadboard so will check it tonight when i get home
as pulse widths can still be varied on master and slave to some extent i would say the comparators are still being somewhat useful though Smile
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PostPosted: Mon Mar 21, 2011 9:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
do you start a run of pcbs or provide the layouts for homebrewing?

still early days on this
will want to add some protection on the logic in's
A run of boards is always possible but that takes time and would depend on
interest from more than a few people
I will do a PNP prototype quad cct board at home first in any case and post all the relevant details after that hopefully next week
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diablojoy



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PostPosted: Tue Mar 22, 2011 12:54 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
BTW did you take a look at the ramp TP when synced?

OK this shed a little more light on things
signal at TP1 on the slave clock is interesting when sync'd to a master
the downward ramp develop's a flat top holding at 5v dependant on the master's pulse width and then only ramping down after the pulse is finished so while C2 is shorted by the CD4016 ramp wave is held high to 5 volts
the pulse width control on the slave affects all pulses from the slave
but since there is now a wider pulse than normal in the mix you dont get the full range on the knob anymore before hitting 100%
As the sync pulse need only be of short duration to acheive sync maybe a fixed comparator between the sync in jack and the logic pin of the CD4016 would be best ? this would restore pulse width control to hopefully full range on the slave or at least very nearly. it would mean losing that wider pulse in line with the sync pulse but as you have voltage control on the pulse width not too hard to get it back
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emdot_ambient



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PostPosted: Tue Mar 22, 2011 8:26 am    Post subject: Reply with quote  Mark this post and the followings unread

You know...I'm only halfway understanding all this Laughing But it sounds incredibly exciting. I'd love to hear these ideas actualized on a sequencer, and look forward to the resulting documentation. I'd only need a dual board, but suppose a quad board could be placed in service only partially populated.

I know there's a ways to go yet on this, but that's cool, too, as I've got probably a year's worth of work to do before I actually get to this project...but it's still exciting!

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diablojoy



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PostPosted: Tue Mar 22, 2011 5:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
I'd only need a dual board, but suppose a quad board could be placed in service only partially populated.

agreed i will work with this in mind
ignore the last part of my last post regarding losing the wider pulse
will still be somewhat wider than the other pulses on the slave
will try to use the TP1 point into a fixed comparator then to an output jack
leaving the clock's normal output jack as is
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diablojoy



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PostPosted: Thu Mar 24, 2011 2:08 am    Post subject: Reply with quote  Mark this post and the followings unread

ok short audio sample
simple patch sync'd clock straight into an A/R gen - VCA with a single VCO
the timing for all of this is from the sync'd clock only no other gates or triggers were used
CV for the VCO is from my foot pedal for the first bit
2nd and 3rd bit the VCO is controlled from a sequencer
3rd bit I changed some settings main ones were
adjust slave PW at 1.05
adjust master rate at 1.25
adjust slave PW from 1.35-2 min
adjust slave rate at 2.10
adjust master rate then the slave rate by a small amount 2.48
will try to get a sample up of the pulse blanking in action by the weekend


sync'd clock test1.mp3
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emdot_ambient



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PostPosted: Thu Mar 24, 2011 8:41 am    Post subject: Reply with quote  Mark this post and the followings unread

thumb up Now, that's actually pretty cool.
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diablojoy



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PostPosted: Sun Mar 27, 2011 2:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

the sync cct works fine but failed to get the blanking cct working stable with cd4016 could be down to stray capacitance of the breadboard or just the wave shape or both but kept getting very odd results impossible to get it working with any sort of stability.
so eventually gave up on CD series chips and tried a DG412 which worked
immediately with no problems
so have changed tack
to do a proper blanking cct will use DG413 instead [ i have some on order which i should get this week ], using the normally open
switches for two sync ccts and the normally closed switches for two blanking ccts. so that means 2x DG413 for a quad unit.
This way on a dual module you can use the same master clock to do both syncing and blanking effectively removing the sync pulse from the output
whilst leaving the slaves extra pulses in the outputted pulse train dependant on the masters pulse width , the slaves clock rate and the slaves pulse width for a given master clock rate between them all there is a lot of variation to be had . hope i have explained this well enough Embarassed

ps : sorry mathias i appear to be hogging your topic with this Embarassed hope you don't mind Smile
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emdot_ambient



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PostPosted: Mon Mar 28, 2011 2:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

diablojoy wrote:
...on a dual module you can use the same master clock to do both syncing and blanking effectively removing the sync pulse from the output whilst leaving the slaves extra pulses in the outputted pulse train dependant on the masters pulse width, the slaves clock rate and the slaves pulse width for a given master clock rate between them all there is a lot of variation to be had...

**opens mouth to speak**
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PostPosted: Tue Mar 29, 2011 12:57 am    Post subject: Reply with quote  Mark this post and the followings unread

I was afraid i would struggle with explaining this Embarassed
so here is an mp3 perhaps it may help with the spiel below
take care it is a click track! start with volume low
again a synced clock slaved to a master clock [soft sync ]
the slave clock is actually running a fair bit quicker
the signal for blanking of outputted notes is also taken from the same master clock and controls the switch across JP1 and JP2 of the slaved clock
starts and finishes with full blanking on which is controlled by the pulse width of the master clock the tempo you hear is the actual rate of the master clock. lowering the pulse width allows more pulses through to the comparator of the slave remember the slave is actually running faster than the master [ soft sync ]
the only control i changed through the entire track is the pulse width on the master clock starting at maximum going to minimum and then back to max right at the very end
there are very many more different variations as
if you change the masters rate the patterns change
if you change the slaves rate the patterns change
and if you change the slaves pulse width the patterns again change
it seems a bit touchy and fiddly to be honest and many settings seem repeats of others or just crappy but then there is some gold in there for such a simple cct


clock sync and blanking click track test.mp3
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emdot_ambient



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PostPosted: Mon Apr 04, 2011 2:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Finally listening to this. There's some pretty interesting syncopation going on here. Some rather latin sounding rhythms.

I'm a bit confused on what we're hearing, though. Is the click made up of the Master's output, the Slave's, or a combination of both?

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PostPosted: Mon Apr 04, 2011 3:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

click track is using the slave output only
patch is straight to an MFOS EG gate input set to min attack / release
MFOS VCO and an MFOS VCA thats it

panelled up a quad unit on the weekend so i can more easily test
four units running at once for any issues ,there could be many as i have had some unpredictable variations at a couple of very fast settings with 2 units which come and go over long time periods of some few minutes,much head scratching over why! not that they were necessarily a bad thing . but i still have some wiring up to do first though before i can do any real testing
also did a preliminary board layout in pcbexpress which i need to refine
further before i try etching it , next weekend i hope
hopefully have some more progress to report next couple of weeks once i get it all off breadboard and on to cct boards behind a panel.
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brother303



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PostPosted: Wed Apr 06, 2011 5:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

diablojoy wrote:

also did a preliminary board layout in pcbexpress which i need to refine
further before i try etching it , next weekend i hope
hopefully have some more progress to report next couple of weeks once i get it all off breadboard and on to cct boards behind a panel.


I think this is really highly impressive! Please keep us updated,I want one of this add-ons... Please

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fonik



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PostPosted: Fri Apr 08, 2011 9:07 am    Post subject: Reply with quote  Mark this post and the followings unread

diablojoy, did you try to use a fixed short pulse for reset? would make the behaviour more predictible, i think. (however i might be completely off track, it is just wild guessong without knowin exactly what you're doing right now)
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PostPosted: Sat Apr 09, 2011 11:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
diablojoy, did you try to use a fixed short pulse for reset?


yes for the reset of C2 for sync have incorporated a comparator using 1/2 x tl072 with a trimmer per cct so you can adjust the pulse duration down as short as possible while still getting the oscillator core to sync OK
tapping in at TP1 for the ramp signal, so glad you added that test point and the extra holes for C2 really made my life easy, no messy board kludges required at all Smile
see attached scheme .
edit :22/4/2011 have changed sync cct it is no longer as described above.
now 1/2 of TL072 is used as non inverting opamp with a gain of 2.33 to increase the inputted ramp wave to 12 volt peak then into one section of a CD40106 via 3300pf cap and 1 meg resistor to gnd to make a leading edge one shot pulse cct of approx 4mSec duration this also inverts the signal then through a second CD40106 to invert back again then to 2n3904 thru a 1k resistor and a 1k resistor at the moment to gnd to adjust the output to approx 12 volts still playing with this value but will do for now there we go much simpler Shocked Rolling Eyes Laughing the indicated signal levels on the schematic are the the measured values from a working cct .
edited plus changes to scheme 26/4/2011
edit : 19/5/11 moved final rev of attachment to post on page 2 so all build docs are now together

Last edited by diablojoy on Wed May 18, 2011 8:48 pm; edited 6 times in total
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PostPosted: Sun Apr 17, 2011 4:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

etched a quad board on the weekend
initial testing showed evidence of latch up of the 2 x DG413 chips occuring at certain settings. with only 2 ccts running eg removing the 2nd DG413 and associated TL072 the cct works ok, though i suspect it is fairly noisy on the supply rails need to look at that Rolling Eyes
So maybe will have to make some changes to the design


edit: problem resolved itself wed 20/4/11
not sure why suspect possibly bad grounding on bench supply but cant prove it fault just dissapeared Confused
will continue testing this for now

Last edited by diablojoy on Wed Apr 20, 2011 3:02 am; edited 1 time in total
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