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external reset and run step 1 for 4017 based sequencers
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2  Next [all]
Author external reset and run step 1 for 4017 based sequencers
diablojoy
something that came about whilst working through my
SympleSEQ64 build.
A question was raised as to the ability to externally reset 4017 based sequencers and actually play from step 1 not reset to step 1 only to then hear step 2 play as the next clock pulse ticks over the sequencer
so i came up eventually with a small simple circuit to do just that.
It has been tested with Foniks VCPS sequencer as well as SympleSEQ
using both Dave kendals M2C module and Foniks Master clock
as clock sources, works quite well in all cases.
note : +10 volt clock and reset trigger or gate signals are required
Really good to use with the M2C as you can always start from step 1
when recording .
This is the single circuit version which is very simple only 2 chips and a few ancillary components
The board as shown is envisioned as an add on board for existing 4017 based sequencers simply wired between the reset jack and the reset in point on the sequencer board the clock input is just tapped from the clock in jack or internal clock .
I will be adding this circuit to all my Fonik VCPS sequencers and also probably to my fonik sequential switches [I have yet to test with those yet, I see no problems there though]
the circuit could also be incorporated into any new 4017 based designs
where there is usually a couple of spare 40106 sections available.
Anyway hopefully other people also find this usefull.
roglok
very cool!
Barcode
This is great! I was just looking into the same thing for a 16 step 4017 based sequencer I'm building. Thanks!
Monobass
what other sequencers use the 4017?
roglok
Quote:
what other sequencers use the 4017?


Ray Wilson's 10 Step Sequencer
http://www.musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&PROJARG= SEQ16_2006/SEQ16_2006.php&VPW=1395&VPH=591

CGS Gate Sequencer
http://www.cgs.synth.net/modules/gate_sequencer2.html
Barcode
Monobass wrote:
what other sequencers use the 4017?


The "baby" sequencers use the 4017 also.
franckboxe
brillant
thanks a lot Diablojoy thumbs up
roglok
Holy Flip-Flop!

Just finished building this. Thank you so much for the circuit, señor!

I think this really was the one missing patch for the Baby10. Implementing this reset fix and the individual trigger mod will turn your Baby into a Monster.

The only issue: I had to replace the 10pF cap with a bridge. For some reason it wouldn't work with the cap in place...

Overall quite a messy build with all the subsequent add-ons... but hey - it works!

falafelbiels
roglok wrote:
Holy Flip-Flop!Overall quite a messy build with all the subsequent add-ons... but hey - it works!



Well no, I think it is a very tidy job actually.I tend to make stripboard horrors. The last one actually broke in three pieces, but it still worked so I paneled it.

Anyway I thought that reset in on the 4017 also disabled clock input, making it reset properly on its' own. Guess I wasn't counting very well...
fonik
w00t
fonik
roglok wrote:
The only issue: I had to replace the 10pF cap with a bridge. For some reason it wouldn't work with the cap in place...

10pF is a very small value. denis, could verify this?
i would have expeted 10nF here?
roglok
Quote:
Well no, I think it is a very tidy job actually.I tend to make stripboard horrors. The last one actually broke in three pieces, but it still worked so I paneled it.


lol You should get epoxy instead of paper stripboard. This changed everything for me. It's not as easy to cut (I use a hacksaw), but much more robust and torsion-resistant!

Quote:
w00t


Big thanks to you as well, Matthias! I built this based on your schematics (Baby10/VCPS8)... The panel bus wiring was also inspired by yours thumbs up
BugBrand
In ref to the 10p cap::

This is making a very short pulse on the rising edge of the Q output - typically you do want a very small value, but perhaps 10p is too small in roglok's case - try 22p/47p/100p etc until it works. Replacing it with a jumper would mean that the Reset Out line would stay hi with Q. (haven't really looked at what is happening, but .... presume you DO want just the short reset pulse rather than a hi constant level)
roglok
Quote:
Replacing it with a jumper would mean that the Reset Out line would stay hi with Q.


Well, it doesn't stay high here. I'm using a short trigger pulse as reset signal and this is also what I'm getting at the 4017 reset input... hmmm.....
roglok
OK, I don't notice any difference, but 22pF does work, so I put it there Mr. Green
roglok
FYI

I added another discrete Schmitt trigger before the 4013 (repurposed form Fonik's reset input) in order to allow resetting from lower level signals (LFOs etc.)... It's peanut butter jelly time!
sicpaul
The idea is great!

But i do not understand how it exactly works.
I hope my replacement of the two inverters with half of a LM358 as a comparator does not affect the functionality.

I build the circuit on protoboard, but it does not work as expected.


The circuit resets my 4017 every incoming clock.

So I try to understand the circuit and i struggle over the second part of 4017 schematic.

R(pin10) and S(pin8) are going to ground, so they are fixed to logical 0.
If I look into the truth table of 4013 i see no matter what S(pin9) input is, 4013 has to react on changing of clock (pin11).
That's what I get. But i don't think that is the intention ....

Can anyone explain it to me?
sicpaul
hmmmm ... no explanations?

i try to learn Mr. Green

in between i tried to use the original 2 inverters instead of my lm358 replacement, but it does not change anything. So i exchanged the second part of the circuit with an AND between clock and Q (made out of 3 inverters from 40106, 2 diodes and a 100k resistor). That gives me only 1 pulse on RESET OUT in time of the next clock pulse after a reset is received. That's perfect.

OK, i got a solution now, but i would really appreciate if anyone could explain to me how the original works ....
...especially what happens in the second part of 4013.


Thanks for help
diablojoy
sorry didnt get any notification on this topic and just saw it
hmm been a long time see if i can remember
basically the first 4013 stores the reset pulse and the second 4013 section releases it at the correct timing with the clock to reset the 4017 correctly this also resets the first 4013 section to be ready for the next time a reset pulse comes in
the 2 x 40106 sections 10pf cap and 100K resistor make up a leading edge trigger pulse of very short duration and an inverter to get the pulse positive.
- play with the cap value a bit if neccesary say 10 to 33pf.
you gain nothing however if the pulse applied is too long a duration, it needs to be as short as possible.

haha damn matthias never got any notice on your post here either
hmm yeah as for 10pf that is what worked for me, it will be something close to that value anyways the pulse really needs to be a short as posssible and still work reliably 10pf is possibly pushing it, rogloks 22pf might be a better choice on average.
sicpaul
thanks diablojoy!

i am such an idiot.
not only that i shortened clock and reset by accident in my first build of your circuit, i exchanged Q and NOT Q in the truth table and did not see it all the times...... d'oh!

Now with a corrected look i understand everything. 8_)
(My LM358 comparator replacement of the two inverters doesn't affect functionality. Like roglok, i use half of it for contitioning reset input, so i had one half left, which i now use to save the 40106).

Anyway thanks a lot for that very useful idea.
Cheers
Paul
diablojoy
Quote:
My LM358 comparator replacement of the two inverters doesn't affect functionality. Like roglok, i use half of it for contitioning reset input, so i had one half left, which i now use to save the 40106).

ah yes good idea thumbs up , i believe you have made an improvement in that case , should possibly have less propagation delay then the 2 x 40106 sections , would you post your scheme here ?
sicpaul
well, i usually do my schematics with pencil and paper hihi
(have to improve my eagle abilities sometimes ... )

so here's an ugly paint redraw of your schematic with LM358


i like the comparator level to be 2V. With 12V rail power the two resistors at pin 2 and 6 of lm358 are 100k and 20k. [/img]
raveboyy
Hi Guys,

I was thinking if it is a good idea just wire a baby8 based on Fonik`s design like this:



In that way, it always resets to Q0=Step8 and start playing from Step1 as it should be...or am I missing something? It probably seems too simple to be true smile
dionnaki
Sorry to bother you. I am just about to start forums baby 10 as my first project just getting everything sorted in my head. Could you please explain the bottom left schematic. J into 3 capacitors? Also where is reset out on the top j plug connected to. Apologies for my lack of knowledge. Thanks.
astrosound
dionnaki wrote:
Sorry to bother you. I am just about to start forums baby 10 as my first project just getting everything sorted in my head. Could you please explain the bottom left schematic. J into 3 capacitors? Also where is reset out on the top j plug connected to. Apologies for my lack of knowledge. Thanks.


You'll see this arrangement of caps pretty frequently on schematics. Their purpose isn't usually explicitly mentioned but they are mounted close to each IC and are tied to the power supply rails to filter noise/reduce instabilities.

For your second question: Top post should answer it.
Quote:
The board as shown is envisioned as an add on board for existing 4017 based sequencers simply wired between the reset jack and the reset in point on the sequencer board the clock input is just tapped from the clock in jack or internal clock .


in other words, "reset out" goes to the reset pin on the 4017
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