all i could think of by now is a propagation delay issue (however, noone reported this behaviour before): the gate is still open when the new clock trigger comes in.
try to leave off the GATE conditioner IC5B, IC5C. does this help?
i will check my builds tonight (hopefully). _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
and in fact i too see this very short pulse. i almost got rid of it by moving the two inverts from the gates path to the clock path. i then had 4 inverters in the clock path to add some propagation delay. at very high speeds i still see the 2nd very short pulse.
i think even without this mod i never recognized the 2nd short pulse just because the subsequent modules i used did not react...
so thanks for your finding. i will look deeper into it the next days. tonight i am done, hehe. i did the mod on a SMT board by desoldering the appropriate pins of the 40106, bending them up, and connecting them by flying wires! has been a little bit fiddly... will be easier on a socketed DIP. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Matthias,
Thanks for looking into this, I too thought that some kind off timing offset might be effective but had no idea how to implement it. If you find a solution I'll be keen to try it, thankfully no SMT for me.
FWIW the short "end" pulse reliably triggers my 281 clone at any speed.
billy
Quote:
and in fact i too see this very short pulse. i almost got rid of it by moving the two inverts from the gates path to the clock path. i then had 4 inverters in the clock path to add some propagation delay. at very high speeds i still see the 2nd very short pulse.
i think even without this mod i never recognized the 2nd short pulse just because the subsequent modules i used did not react...
so thanks for your finding. i will look deeper into it the next days. tonight i am done, hehe. i did the mod on a SMT board by desoldering the appropriate pins of the 40106, bending them up, and connecting them by flying wires! has been a little bit fiddly... will be easier on a socketed DIP.
i just did a quick spice simulation during my morning brake using a RC delay: i put a 10 resistor followed by a 100n cap to GND between two of the inverters.
makes a nice delay, however, i don't know about the exact maths. according RC time constant we would get 1/1000 sec... anyways, you see the problem here: the delay is constant while the speed of the sequencer changes. we will have to find a good compromise, i guess.
i hope to find some time this week to implement this on one of my sequencers, and to find good values. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Matthias I think this looks like the issue i came across a while back scott stites has a good example of the behaviour on his
matrix sequencer page that he is working on, it seems it is inherent to the 4017 operation which overlaps its outputs
if it is the same problem i did a little slew daughter board a while ago to get round it for the sequential switch part on that ludicrous symple64 build of mine.
I will dig up the details when i get home tonight and see if it can be incorporated somehow from memory the slew delayed the leading edge of the clock by around 150usec
cheers
Denis _________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any
i think even without this mod i never recognized the 2nd short pulse just because the subsequent modules i used did not react...
yes the second pulse is very short around 50+ usec's
this is the overlap of the 4017 outputs where output 2 goes high before output 1 goes low and so on for each output used
find attached how i got around this on the sequential switch circuit i mentioned, it was very neccesary in that case as i was switching clock signals though not so much generally with a straight sequencer as most EG's will not react to such a short pulse or so i thought it seems
It hasn't been an issue with my VCPS-8 so far
On the VCPS-8 the attached circuit would need to go between IC6 pin 14
and IC5 pin 11 , there is a small via between IC11 and C18 that would make a good point to solder a wire to from the output of the daughter board and you would need to cut the trace heading back to IC6.
this should have the effect of shortening the start of the clock pulse that is anded with the gate pulse till after the previous step output has released.
For the input to the daughter board i think you could get away with just running another wire from the clock in jack. edit : hmm better maybe to kludge a wire off D21/D22 cathode end instead.
the attached circuit adds a glide to the leading edge only of the pulse
so it is a little better than a simple RC circuit, admittedly it is also quite somewhat more complex. and i have not tested it with a VCPS-8 but it has been tested with a 4017 based sequential switch
If you go ahead and decide to try this the foil attachment should simply be printed straight onto pnp blue just check the scale is correct first though it should be correct.
will try this simple delay in the clock line tonight:
[edit: picture updated and embedded] _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source Last edited by fonik on Wed Jul 25, 2012 3:50 am; edited 1 time in total
okay, i just tested it during the lunch brake. my simple clock delay circuit works like a charm. i ended up with the trimmer set at about 9k, so 10k should still be working nicely.
SO ALL WHO EXPERIENCE PROBLEMS WITH A 2ND (GATE OFF) TRIGGER GENERATED
refering to sketch in post above:
1) bend up pins 10 & 13 of IC5 (the 40106 hex inverting schmitt trigger) - hopefully you have them socketed.
2) solder a 10k resistor between these pins (right on top of the IC).
3) solder a 100n cap from pin13 IC5 to GND (i.e. at the decoupling cap). _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Mod works really well, though I had to use 200n. It's a great module..........
fonik wrote:
okay, i just tested it during the lunch brake. my simple clock delay circuit works like a charm. i ended up with the trimmer set at about 9k, so 10k should still be working nicely.
SO ALL WHO EXPERIENCE PROBLEMS WITH A 2ND (GATE OFF) TRIGGER GENERATED
refering to sketch in post above:
1) bend up pins 10 & 13 of IC5 (the 40106 hex inverting schmitt trigger) - hopefully you have them socketed.
2) solder a 10k resistor between these pins (right on top of the IC).
3) solder a 100n cap from pin13 IC5 to GND (i.e. at the decoupling cap).
yep. for a 2nd module i had to go up to 33k. maybe a trimmer instead of a fixed resistor would be the way to go? _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
meanwhile the sequencer is available as eurorack module via schneidersladen and analoguehaven. however, you could buy a module directly from me.
anyways, i am planning to do a new version with front panel adapter PCBs for 4U/Serge and Eurorack. no schefude yet. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
we emailed, no?
your package is on it's way already... _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Recently did a euro build of this
came out ok still working out a bug or two though
aged a gated slew and a run /stop button
(first time I did a self etch double sided board for the panel controls only)
still have to do a second one.
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_________________ In an infinite universe one might very well
ask where the hell am I
oh yeah thats right the land of OZ
as good an answer as any
wow! that looks great. and see a build after all these years!
i am working on a MK2 from time to time. it has a s/h for the CV output and the pattern could be loaded by an external pulse (latch for the ADC). the first eurorack prototype had some errors, the 4U version worked out well, though.
the eurorack MK2 has slider jsut like yours, the 4U come in two versions, one with CV, another just with gate outputs:
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
Waking up .. 10 years after ... this is a nice idea
Hm .. but with step count selectable from 1 to16, a dir input and pattern inversion (upside down) .. then come to think of it .. set the pots to random values in some controlled way .. something like that.
/me starts drawing & coding for the soft synth ...
heh .. one can never have enough sequencers .. seemingly .. or maybe that's just another way to say that all sequencers suck .. anyways .. to work. _________________ Jan
also .. could someone please turn down the thermostat a bit.
Waking up .. 10 years after ... this is a nice idea
Hm .. but with step count selectable from 1 to16, a dir input and pattern inversion (upside down) .. then come to think of it .. set the pots to random values in some controlled way .. something like that.
/me starts drawing & coding for the soft synth ...
heh .. one can never have enough sequencers .. seemingly .. or maybe that's just another way to say that all sequencers suck .. anyways .. to work.
haha, yes.
i am not into coding Jan, but just recently i bought myself a book for beginners, starting with C and Arduino, then continuing with C++ and Teensy. And the first thing I wanted to do was a sequencer.
regarding 16 steps:
16 steps would mean 16bit, thus too many different patterns one could select with just one control voltage. I rather thought of making the 8-step chainable. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
regarding 16 steps:
16 steps would mean 16bit, thus too many different patterns one could select with just one control voltage. I rather thought of making the 8-step chainable.
Hmm .. that seems to make sense .. will experiment a bit .. it may not be as much of an issue for a digital synth, but will need some tinkering about how to control it ... will have to see where it ends up. Thanks for your thoughts about this.
Re. coding .. more computers into the rack ... already seeing lots of interesting modules based on that idea _________________ Jan
also .. could someone please turn down the thermostat a bit.
Re. coding .. more computers into the rack ... already seeing lots of interesting modules based on that idea
Seriously, I am not interested in digital sound generation. I love the idea of analog. But I recently worked on the Serge TKB, which has a quite complicated CMOS logic (at least for me it is). And I start to believe that especially all this logic could perfectly put into the digital software controlled domain without compromising the idea of having analg audio. _________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source
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.. anyways .. to work.
