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idea for a gate sequenzer
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g.gabba



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PostPosted: Thu Jun 28, 2018 10:27 am    Post subject: idea for a gate sequenzer
Subject description: using (cheap) pushbuttons
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i have many of those little pushbottons left,
so i was thinking about how to use them in a sequenzer,
attached an idea for a gate sequenzer,

one had to push two buttons at a time to programm it, set or reset button and the desired step button

on the gateout one could attach a 4017 with pots to have CV, whitch has the atvantage that the CV would stay until the next gate impulse comes

the caps will decharge over the time but it will take a long time until they go under 0,6V (one could use smaller caps to add somekind of randomness when the seq starts to forget Smile

cu, gabi


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Grumble



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PostPosted: Sat Jun 30, 2018 11:03 am    Post subject: Reply with quote  Mark this post and the followings unread

or you might add a cd40175 quad flip-flop and it will never forget Laughing
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elektrouwe



Joined: May 27, 2012
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PostPosted: Sat Jun 30, 2018 1:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

get rid of the TL071 and use a noninverting buffer (spare gate, or 2 inverting in series) instead. With a feed forward resistor of 100k between in and out of the buffer the caps (100nF then) will "autorefresh" forever.

I have a similar touch sequencer: Instead of switches there is a SET and a RESET touch input. each connected via diode to the storage cap.
SET diode direction is cathode to cap, RESET diode is connected anode to cap. And there is TOUCH electrode connected to a square wave oscillator. When I touch this electrode with my left hand and either a SET or RESET einput with the right hand, I can program the sequencer.
cap values must be small (nF range) because skin resistance is high. A more reliable solution is to use a "stylus" conneted to the square wave osc. and touch the SET/RESET inputs with it. Then100nF caps are ok.
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PHOBoS



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PostPosted: Sun Jul 01, 2018 4:02 am    Post subject: Reply with quote  Mark this post and the followings unread

I'd go with some flip/flops too. Besides being more reliable you can toggle between set/reset with a single button.
The comparator on the output is not a bad idea in this case.

elektrouwe wrote:
With a feed forward resistor of 100k between in and out of the buffer the caps (100nF then) will "autorefresh" forever.

hmm so that would be from the gate output back to the common (Y) of the mux ? at least that's how I think it could work Very Happy.

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Blue Hell
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PostPosted: Sun Jul 01, 2018 7:10 am    Post subject: Reply with quote  Mark this post and the followings unread

Hmm .. I like that idea - sequences that forget :-)
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PHOBoS



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PostPosted: Sun Jul 01, 2018 8:25 am    Post subject: Reply with quote  Mark this post and the followings unread

that sounds a bit sad Sad

hmm a neuron sequencer might be nice, with false memories.

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elektrouwe



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PostPosted: Sun Jul 01, 2018 9:57 am    Post subject: Reply with quote  Mark this post and the followings unread

PHOBoS wrote:
I'd go with some flip/flops too.

well, "some" means 16; not a small #

PHOBoS wrote:
hmm so that would be from the gate output back to the common (Y) of the mux ? .

yes
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elektrouwe



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PostPosted: Sun Jul 01, 2018 10:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Blue Hell wrote:
Hmm .. I like that idea - sequences that forget Smile

you don't play live in front of a dancing crowd, don't you ? Wink
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Blue Hell
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PostPosted: Sun Jul 01, 2018 1:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

erm Evil or Very Mad I like the idea of sequencers that forget Rolling Eyes
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g.gabba



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PostPosted: Mon Jul 02, 2018 11:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

i liked the alzheimer-idea also ,-) was thinking about different cap values

jaja flipp-flopps, but i can only source them next year same time

what a great idea with the feed-bag, would than this also work somehow?


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Grumble



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PostPosted: Tue Jul 03, 2018 12:58 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, a little...
Remove R12, there is no need for that resistor and adds just a parallel impedance to the capacitors.

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elektrouwe



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PostPosted: Tue Jul 03, 2018 1:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

g.gabba wrote:

what a great idea with the feed-bag, would than this also work somehow?

no, won't work. you need positive feedback (noninverting Schmitt-Trigger)
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IGR



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PostPosted: Wed Jul 04, 2018 7:46 am    Post subject: Reply with quote  Mark this post and the followings unread

Does anyone know the sequencer of the Leploop V1? I think switched capacitance analog shift register is used there. This term was until today a bit mysterious to me. Thanks friends!
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elektrouwe



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PostPosted: Wed Jul 04, 2018 10:27 am    Post subject: Reply with quote  Mark this post and the followings unread

IGR wrote:
...Leploop V1? I think switched capacitance analog shift register is used there. ..


didn't know this sequencer yet. google found " the LEPLOOP has a 16-step analog recorder, much like an analog delay.Over time, as the analog sequencer cycles through its pattern, the signal will degrade and the sound will hange. This is because the capacitor can only store the signal for a limited amount of time"

for a step sequencer storing only 0V and VDD, refreshing the memory is easy with a noninverting Schmitt-Trigger as described above. For real (quantized) analog storage you would need an ADC that reads
the actual (already slightly drifted) analog voltage and refreshes the original voltage with a DAC. I've sketched a 3bit solution with 8 comparators and a 8/3 decoder as ADC and a 4051 with linear R string as DAC.
But in microcontroller days it's too much effort to do it Lunetta style.

Last edited by elektrouwe on Wed Jul 04, 2018 12:31 pm; edited 2 times in total
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IGR



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PostPosted: Wed Jul 04, 2018 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Clearly, I understand. But I find MUX as bidirectional switch for read/write operation very simple, useful. During ~10% of CV step duration to read voltage by S&H, then during 90% of CV step write its value back to capacitor. At output will be while whole step duration still right CV value. Maybe 4066 switch or FET controlled by short monostable triggered by clock. Touch sensitive CV sequencer that´s exciting idea. To be able to "tune" sequences on the fly with finger pressure, something like to inflate tyres at pump +/-! Impro friendly piece of gear.
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Blue Hell
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PostPosted: Mon Jul 09, 2018 3:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've made a leaky gate sequencer for my soft synth .. its doing nice stuff .. but am not totally happy yet with the forget curves .. too abrupt ... also I want negative forget .. negative leakiness ... as in that it can grow back from sparse to the programmed pattern. So still experimenting a bit with it .. but what a nice idea :-)
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g.gabba



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PostPosted: Tue Jul 10, 2018 11:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

iam glad to hear it is something enjoyable:-)

we need voltage controlled leakyness, in the negative half it will forgett more and more, in the positive it will look into the future more and more
Cool

or in reality one could connect a vca to the falling voltage in the cap so it would fade out before forgetting, somehow at least
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