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lostinpurdy
Joined: Nov 16, 2007
Posts: 37
Location: Gig Harbor
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 Posted: Sat Dec 29, 2007 12:35 am Post subject:
Noob needs help
Subject description: building a diy sequencer with step memory |
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Hello, all and eveyall ! I have recently found interest into making musicall devices with electronics and have experimented with various 555 based designs, documented and made up, now I really would like to build myself a simple sequencer utilizing the 4017 IC. I want to keep the size and parts count as small as possible. I'm thinking of simple design where I set a step with one or two pots and push a button to store the information and move to the next step. Now I pretty much figured out the 4017 part where everything goes, etc. but I have absolutely no clue how to aproach the step memory section. Which type of chip do I use to store 10 steps of sequencer information? Any ideas, even schematics are highly appreciated!
Greetings, Patrick
PS: What would the CV output be? 1V/oct or HZ/V? If not HZ/V how can I modify the output to work with some of my old synths (Korg, Yamaha HZ/V type)? |
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Joel
Joined: Sep 12, 2006
Posts: 97
Location: London, UK
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| Posted: Sat Dec 29, 2007 5:44 am Post subject:
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Hi Patrick,
for a very simple sequencer try looking at something like the Baby 10 - this uses a 4017 but has a pot for each step. As far as I'm aware there isn't a logic chip you could use to store values for multiple steps, so you'd have to use a microchip-based solution - see the Arduino Punk Console for an example although that adds some extra bits you haven't mentioned, like a screen 
Good luck, keep us posted!! Joel
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fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
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Posted: Sat Dec 29, 2007 7:23 am Post subject:
Re: Noob needs help
Subject description: building a diy sequencer with step memory |
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| lostinpurdy wrote: | | PS: What would the CV output be? 1V/oct or HZ/V? If not HZ/V how can I modify the output to work with some of my old synths (Korg, Yamaha HZ/V type)? |
the output would be just a voltage. the 1V/oct or Hz/V describe actually the behavior of the VCO.
my baby10 sequencer has no quantizer, so it outputs a CV not quantized to steps according such a 1V/oct standard or whatever.
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matthias
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Big Boss at fonitronik
Tech Buddy at Random*Source |
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Clack
Joined: Aug 08, 2005
Posts: 438
Location: Walthamstow - london
Audio files: 5
G2 patch files: 1
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Posted: Sat Dec 29, 2007 11:33 am Post subject:
Re: Noob needs help
Subject description: building a diy sequencer with step memory |
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| lostinpurdy wrote: | | I'm thinking of simple design where I set a step with one or two pots and push a button to store the information and move to the next step. Now I pretty much figured out the 4017 part where everything goes, etc. but I have absolutely no clue how to aproach the step memory section. Which type of chip do I use to store 10 steps of sequencer information? Any ideas |
you can use a track and hold to store a voltage, I have no idea how accurate you can make it though. Reading on the SDIY list archives it says that most analog T&H/S&H's tend to droop after a bit ( they leak and the voltage drops ). it would be rather part heavy too as you would need a track and hold for each step.
the T&H lets the voltage through as normal when its logic input is high, then holds it when the logic goes low.
Been trying to do somthing similar recently but instead it would record the CV levels of a keyboard.
Here is what I cane up with - thanks to blue hell for reccomending G2 demo you can almost simulate most synth circuitry with it !
Part count is -
3 or's
1 AND
2 4017's
1 4016
a clock ( 555 ? )
4 track and hold circuits
some of the OR's may not be neccesary - the editor does not allow you to input 2 trig/gate signals into the same input - this would be a problem if they were operating at the same time - but in our case only 1 input of the OR is active at any one time
Cant go into depth how it works now but looking at this patch you should be able to work it out. Red part is controlls, blue/green is CV section and purple the gate section
To operate it -
When record/play button is on it plays the sequence, when it is off it is in record mode, set the pitch in 'CV level' then advance to the next step with 'step butt.' when you get to the 4th step avoid pressing advance as youll go back to the first step and overwrite it.
Probably not very elegant but I have only just started laying out circuits ! its one of those things that seems simple then gets more and more complicated - problems with this design is - T&H may not be too stable in real life, you need a T&H for every step, you cant go back and edit individual steps they all have to be written at once and they cant be edited on the fly, the step button may need to be deactivated when in playback mod - better option would be microcontroller or some other kind of A/D - D/A thing
In the end it is far easier to have 'mechanical memory' where there is a pot for each step
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