simple 8 step sequecer for SL

guskenny83 · Posted: Wed Aug 19, 2009 8:13 am Post subject:

hi,

not sure if this thread is still running, but i have a couple of questions i'd like to ask about building sequencers.. i have only got into this whole thing quite recently..

firstly, i have built basic square wave oscillator that goes from 100-1000Hz based on a schematic i found in a book of 555 projects and im interested in building an 8 step sequencer to run it off..

looking at some of the posts on this thread, and looking at various "knight rider lights" projects, i think i have a basic idea of what i want to do..

i juts have a couple of questions about how it all works..

if i build another 555 oscillator, would that be sufficient as a clock signal for the 4017? is it each pulse of the square wave that triggers the steps of the 4017? what would be a useful range of frequencies for the clock signal so as to be able to vary the step speed a decent range?

also, im a little confused about what happens after the 4017..

is the input voltage just re-routed to each of the pins with each step? so does that mean, in order to control the oscillator i just need to hook up each of the outputs from the 4017 via a diode to the V+ of my oscillator circuit?

what would be the effect of putting a pot between each step of the 4017 and the oscillator? would that cause the frequency of each step to be different, still using just the one oscillator?

sorry if my questions seem obvious or confusing, i just want to get an understanding of what is actually happening between the 4017 and the oscillator.. i suppose i could just breadboard it and muck around, but i dont really want to spend the money on the components til i have an idea of how it all works..

alright, thanks for your help

cheers
gus

Danno Gee Ray · Joined: Sep 25, 2005 Posts: 1075 Location: Telford, PA USA

Gus,

I'll try to answer some of your questions. First I would recommend a little research on your part. Look up the "baby 10" sequencer, both on this board and on the internet. Then look up the basic 8 step or 10 step sequencer on the "Music From Outer Space" or MFOS website. Ray has a wonderful way of explaining his circuits that may well answer a multitude of questions.

Regarding you specific questions.

a basic squarewave oscillator will work well to drive the 4017 based sequencers. Although the speeds you mentioned are a bit too high. This driver oscillator is also known as an LFO, or Low Frequency Oscillator. for sequencing purposes you might want it to go from very slow (1 Hz or maybe less) up to 50-60 Hz? depends on what effect you want.

The 4017 is effectively a clocked switch that changes or switches the input voltage to an output port at each cycle of the clock. If you connected each output of the 4017 directly to the output or Voltage Controlled Oscillator the tone would be the same at each step. Using a Potentiometer or variable resistor at each output step allows you to vary the output voltage at each step and produce different tones.
Take a look at the resources cited above and let us know if this helps.

Good luck,

Danno

guskenny83 · Posted: Wed Aug 19, 2009 3:56 pm Post subject:

thanks a lot for that..

thats basically everything i wanted to know.. at least now i can get the components and do a bit of experimentation.. i had read the article on the baby 10 and a few others, but none seemed to mention what actually happened between the sequencer and the tone oscillator..

youve been very helpful

cheers
gus

mosc · Posted: Wed Aug 19, 2009 3:57 pm Post subject:

Gus. Great to have you hear.

Our threads never die.

Danno Gee Ray · Joined: Sep 25, 2005 Posts: 1075 Location: Telford, PA USA

Gus,

Glad to be of service. Enjoy the experiments!

and yes, Welcome aboard Very Happy

acidblue · Joined: Jun 26, 2009 Posts: 68 Location: The Darkside

Just in case anyone needs it, that layout software that kxspxr mentioned
can be found here:
http://www.diy-fever.com/forums.html?project=software

The original link is long dead.
I can confirm it runs fine on linux, I'm running Ubuntu 9.04
java -jar file.jar

guskenny83

hello again,

thanks a lot for all your advice before, it was greatly helpful!

i succeeded in making a simple 4 step sequencer on a breadboard, but didnt go further because i havent decided exactly what i want to do with it yet..

i have a question though, which might be very stupid and impossible to do, but im just wondering if it could be done..

i just recently got my hands on a friend's roland SH-1000 synth, and its great, but unfortunately it has no CV input, so im not sure how i could use the sequencer i built with it..

is there a way that i could use it "at the other end" so to speak, so instead of using the sequencer as a control voltage, to put an input jack in the sequencer and make the circuit such that the signal from the synth will only get to the output jack on the sequencer if the step is switched on?

at uni we're just starting to learn about mechatronics and logic gates and things and i was wondering if i could use an AND gate with the output of the sequencer in one input and the signal from the synth in the other, so that it would only output anything if both inputs were true..

first of all, would this work at all? and secondly im not entirely sure of how an AND gate works, if both inputs are true, which of the inputs is allowed to go through? or are both? and if that is the case, would it make a difference to the output if the signal coming from the sequencer is added to the signal from the synth? is there a type of gate that when both inputs are true, it only lets one of the inputs through and uses the other input just for a control?

so many questions! sorry if its confusing, im having trouble putting what i am thinking into words, just trying to get my head around it.. if its possible it would be pretty useful, as you could use it with guitars or anything that has an output voltage..

i guess the basis of what i want to make is something that can interrupt the flow of a voltage at selectable equal increments..

anyway, any help would be greatly appreciated!

cheers
gus

Danno Gee Ray · Joined: Sep 25, 2005 Posts: 1075 Location: Telford, PA USA

Sorry to it took so long to get back to you Gus.

I think what you would need for your latest idea would be a VCA. Voltage Controled Amplifier. By controlling the VCA with a clock signal or in your case one of the outputs of the sequencer, you can turn on or turn off the signal being passed through the VCA.

Musically, Don't know how usefull that would be.