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 Forum index » DIY Hardware and Software » Musical Interfaces
From Scratch Step Sequenzer
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PeterF



Joined: Jul 03, 2010
Posts: 11
Location: Germany

PostPosted: Mon Jul 05, 2010 11:32 am    Post subject: From Scratch Step Sequenzer
Subject description: electrcial Specs and Ideas
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Hi Folks!
I got a lilltle problem, i am a bloody beginner when it comes to modular Synths and Electrical Musik ein general, i think i have no knowledge at all.
But i do have a good background in elektronics, programming, microcontrollers, music and music equipment.

Over the past weeks a read quite a lot on the subject and i think i got the whole thing figured out Wink

I decidet to build my own step Sequenzer, VCO and a noise generator to play around a bit, its a cheap way for me to get a first feel about the whole thing.

I decidet to build a 8 Step sequenzer for a start, based on a µC with a ADC and a DAC with 10 Bit resolution at both sides.
If that is a good idea or not i dont know but i want to make a "digital" step sequenzer.

It should however output a CV and here is a Problem.
What voltages do i need to put out to interface with regular modular Synths?

0 to +10 Volts?
0 to +15 Volts?
Or even Negative Voltages?

I was planning to add a modulation capeability to the CV out, simple Rect, Saw, Sine and Ramp. And a Soft change from one Step to the other, like fadeing from one Voltage to the other.

All that is perfectly within my electronic prowers Wink
I just dont know what size and Shape should the output signal be.

There are anny things i should consider before i start?
Anny dos and donts?
Things to put in?

Greetings,
Peter

P.s. Please go easy on my grammar and spelling, english is not my native language Wink
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Rykhaard



Joined: Sep 02, 2007
Posts: 1290
Location: Canada

PostPosted: Mon Jul 05, 2010 2:14 pm    Post subject: Re: From Scratch Step Sequenzer
Subject description: electrcial Specs and Ideas
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PeterF wrote:
Hi Folks!
I got a lilltle problem, i am a bloody beginner when it comes to modular Synths and Electrical Musik ein general, i think i have no knowledge at all.
But i do have a good background in elektronics, programming, microcontrollers, music and music equipment.

Over the past weeks a read quite a lot on the subject and i think i got the whole thing figured out Wink

I decidet to build my own step Sequenzer, VCO and a noise generator to play around a bit, its a cheap way for me to get a first feel about the whole thing.

I decidet to build a 8 Step sequenzer for a start, based on a µC with a ADC and a DAC with 10 Bit resolution at both sides.
If that is a good idea or not i dont know but i want to make a "digital" step sequenzer.

It should however output a CV and here is a Problem.
What voltages do i need to put out to interface with regular modular Synths?

0 to +10 Volts?
0 to +15 Volts?
Or even Negative Voltages?

I was planning to add a modulation capeability to the CV out, simple Rect, Saw, Sine and Ramp. And a Soft change from one Step to the other, like fadeing from one Voltage to the other.

All that is perfectly within my electronic prowers Wink
I just dont know what size and Shape should the output signal be.

There are anny things i should consider before i start?
Anny dos and donts?
Things to put in?

Greetings,
Peter

P.s. Please go easy on my grammar and spelling, english is not my native language Wink


Welcome to electro-music.com Peter! Smile Seeing the # of people that've read this message before I, I'm quite surprised that no-one else has answered you yet. scratch

Now - for the output voltage ... how are you determining on each of the 8 steps, what voltage that you would like? The answer to that, could very well be a portion of what amount of voltage coming out, that you would like.

If you wish to have discrete musical notes in a scale / etc., from the output, then 0 to +5V would be a good range.

If you'd like to use the 8 steps for sending Control Voltages to be used for things other than VCOs, then 0 to +10V is one of the used standards.

A couple of lesser standard voltage ranges, including LFO / VCLFO outs, include -5 to +5V and -10 to +10V.

Curious - since you're doing it digitally - what system are you considering doing it around? By chance - if PIC based, then I'm VERY interested, as I'd recently FINALLY ordered myself a Microchip PICKit 3 and am currently teaching myself that area. (Just about to do my 1st VCLFO with another chap's code, that I'm using to teach myself the related Assembly language. (I've programmed in various Basic languages for the last 28 years, on / off. I also know enough in electronics theory, to do some simple designs for things, of my own. Smile ))

As to your English - no problem here! I were able to understand everything that you typed / meant, with no troubles at all. Smile

Any more questions - fire them away. There's almost always someone here who's able to answer. Very Happy
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PeterF



Joined: Jul 03, 2010
Posts: 11
Location: Germany

PostPosted: Mon Jul 05, 2010 3:05 pm    Post subject: Re: From Scratch Step Sequenzer
Subject description: electrcial Specs and Ideas
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Sorry... hit the wrong button.
Last edited by PeterF on Mon Jul 05, 2010 3:08 pm; edited 1 time in total
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PeterF



Joined: Jul 03, 2010
Posts: 11
Location: Germany

PostPosted: Mon Jul 05, 2010 3:07 pm    Post subject: Re: From Scratch Step Sequenzer
Subject description: electrcial Specs and Ideas
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Rykhaard wrote:

Welcome to electro-music.com Peter! Smile


Thank you! ^^

Quote:

Seeing the # of people that've read this message before I, I'm quite surprised that no-one else has answered you yet. scratch


Must have been the Google Bot Wink

Quote:

Now - for the output voltage ... how are you determining on each of the 8 steps, what voltage that you would like? The answer to that, could very well be a portion of what amount of voltage coming out, that you would like.


Here is a quick Setup, missing all the Buttons, LEDs and Switches Wink

Posted Image, might have been reduced in size. Click Image to view fullscreen.

The Pots serve as Voltage deviders, the ADC in the µC reads the Value bewteen 0V and 5V in 1024 Steps.

At the given Step the µC Ready the Value of Channel 0 and outputs the Value to the external DAC.
The DAC then outputs a Voltage vom 0V to 5V corresponding to the value the µC dit send.

The DAC is buffered by a Op Amp with determines the Final output Voltage, The voltage can be whatever the OpAmp ist set to, but only in the 1024 Steps the setup is capeable of.

Quote:

If you wish to have discrete musical notes in a scale / etc., from the output, then 0 to +5V would be a good range.

If you'd like to use the 8 steps for sending Control Voltages to be used for things other than VCOs, then 0 to +10V is one of the used standards.


Thanks, that is what i wanted to hear Wink
The Sequencer alone should not output anny "Music" just a control Voltage to control a VCO or a something else that transforms that Voltage into a sound.
That is what i tought a Sequenzer should only do, if i am right.
Is that the correct Setup?

Quote:

A couple of lesser standard voltage ranges, including LFO / VCLFO outs, include -5 to +5V and -10 to +10V.


Mhm. that could be done with a OpAmp, since i get a 0 to 5V signal from the Controller i can level shift it.
But i think ill only but in a switchable 0to5 and 0to10 Output signal.

Quote:

Curious - since you're doing it digitally - what system are you considering doing it around? By chance - if PIC based, then I'm VERY interested, as I'd recently FINALLY ordered myself a Microchip PICKit 3 and am currently teaching myself that area.


Ill be using a Atmel AVR when the day comes i finally start soldering Wink
Ive done a couple of things over the last years with them, some quite big, so i think ill be able to manage it ;^^

I fear it might be a bit slow with only 20MHZ to do all the things i want but ill see. If its too slow i just have to omit some features.

Regards,
Peter
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PeterF



Joined: Jul 03, 2010
Posts: 11
Location: Germany

PostPosted: Mon Jul 05, 2010 3:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

I just remembered 2 additional questions.
I understand the Gates, the gate determines if a step is active or if the sequenzer for the duration of the step will output 0v.

Right?

I saw gate outputs on some sequencers, what to they do?
Do they output a pulse for X milli seconds when the gate is on or a fixed voltage the whole time?

Then there is the external Start and Trigger input.

The Start does start the sequence when the machine is in stop mode and runs the programed sequenze and stops again?

The trigger input is an override for the Internal clock?

Thanks in advance!
Peter
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JackRabbit



Joined: Aug 15, 2010
Posts: 8
Location: USA - Virginia

PostPosted: Fri Aug 20, 2010 10:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Essentially gate is note on off. I have been running into issues on my sequencer design where the notes all just sort of run together [no 0v rest period]. Trigger in is a pin on your clock [I assume a 555 chip]. If the internal clock rate is turned up too fast, it will override any external input, so keep this in mind. If it's turned up only slightly, I found that the steps get this neat little shuffle to them.
Nit sure about ext start stop. That's something I have yet to work out. Sorry :/
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max92



Joined: Aug 04, 2010
Posts: 17
Location: Sweden

PostPosted: Sun Sep 12, 2010 11:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

This will be my first post here to, and it might seem like i am trying to steal the thread and if so, moderators may feel free to branch it off! Smile

I have started to build a modular system with Oakley and YuSynth modules. Right now I have:
1x Oakley VCO
1X Oakley MidiDAC
1x Oakley VCA/ADSR
1x YuSynth Moog VCF

My plan is to build a simple VC-controlled sequencer. I have made a frontpanel in i paint (attached).
Basically it is one 8 steps, one row of CV/Gate and two rows of trig. It has a 1V/OCT in so it can as an 8-stepped arpeggiator. I had in mind of building it around three 4017 and one 555 as clock. What do you think of this? could it work? I could need some help in making a schematic for it.


Seq.png
 Description:
My sequncer front panel. Made as a 2U rack unit.
 Filesize:  11.13 KB
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This image has been reduced to fit the page. Click on it to enlarge.

Seq.png


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Skellz



Joined: Dec 31, 2008
Posts: 18
Location: Ireland

PostPosted: Tue Sep 14, 2010 3:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi max92

Here is foniks version of the baby10 sequencer http://www.modular.fonik.de/Page22.html

You should also have a look at the original baby10 there is a link for it on that page
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max92



Joined: Aug 04, 2010
Posts: 17
Location: Sweden

PostPosted: Tue Sep 14, 2010 4:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Skellz wrote:
Hi max92

Here is foniks version of the baby10 sequencer http://www.modular.fonik.de/Page22.html

You should also have a look at the original baby10 there is a link for it on that page


The article I had found, but not that link so thank you very much!
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