16 step CV Sequencer

[teej212]

I am looking for a diy sequencer like the ones on the super seeker zvex pedals - 16 steps necessary, glide would be nice, tap tempo not needed.

preferably a kit? tons of 8 steppers out there but not 16!

[R.G.]

Not too difficult.

Can you program PICs, Att, or Arduino? Otherwise, it's going to be a clot of hard logic and hard to deal with from the user standpoint.

[teej212]

yeah can work with arduino

[R.G.]

It's pretty simple in concept. Bunch of pots and LEDs. Each pot is connected to [here] by a cmos switch when it's activated. The activation signal for the cmos switch is a logic '1' out of the programmable thingie. The activation signal for the cmos switch also turns on the LED per pot.

[here] is a voltage follower that buffers the control voltage it gets. Good choices for [here] are a simple voltage follower for steps, and an R-C filter with variable R for setting the glide speed, which is what I think "glissando" or "gliss" is. You could also use a noninverting lowpass filter for this, but I'm guessing you want variable glide speed from nearly steps to slow glide.

If you don't have enough (i.e. 16) pins out of the Ardoo for turning on channels, use it to run either addressable latches or strobed shift registers. The CD4094 or 74HC4094 chips will do this, and can be cascaded to near-infinity. You get eight outputs per 4094.

[alanp]

Thing is, with 8 steps you only need a 4017, maybe a LM358, and that's about it as far as ICs go.

[mattoverse]

Thing is, with 8 steps you only need a 4017, maybe a LM358, and that's about it as far as ICs go.

I thought you could do 16 steps with 2x 4017?

[mth5044]

You definitely can, check the data sheet

[anotherjim]

You can cascade n 4017's...

Notice you can only use the first 9 outputs from the 1st counter(Q0-Q8. So you need 7 outputs from a second(Q0-Q6). Reset will be from the second counters Q7. The scheme shows an AND gate is required, but a diode gate will work to save adding another chip...

As it's CMOS, the resistor can be 100k.

[teej212]

can something like this be modified to output cv and have pots vary the level of cv?

http://www.bakatronics.com/shop/item.aspx?itemid=741

[mth5044]

It's hard to tell without a schematic or knowing what exactly that micro controller is doing. If you are looking for a CV controller, you can definitely go with the 4017. Do a google search for 4017 sequencer and synths, you'll get a handful. I'm sure there are a lot of similar projects that use arduino - a quick search of their forum shows a lot of similar projects.

[spyrusthevirus]

I'm also working out the same thing.
I figured I'd go with 4017, like people already said. They are cheap and can be cascaded to eternity and there are reset and count enable functions on them, which is helpful in musical applications. There is a project, "baby 10 sequencer" I believe, which is a fairly standard realisation of a CV sequencer, that should clear things up.
Each Qx from the 4017 goes to a potentiometer (to adjust the CV) and that goes to a summer circuit (using any standard opamp). You can implement glide functions by using capacitors on the CV outputs. If you want the glide to be universal for every step, you connect the cap between the summer input and the ground. However, if you want glide to be enabled/disabled for every step, you might be able to do it by connecting the caps right after every potentiometer...I might be wrong though, I have not tested that idea yet.
You will also need a clock to drive the sequencer. You can easily make one using a 555 or you can interface the whole thing to MIDI, using an arduino compatible board (or any other microcontroller), that is programmed as a midi to clock converter. I have written the basic code for that function, that also implements reset whenever the DAW sends a start signal. I could post it for you, if you need it.
The usual configurations of such a sequencer only output positive voltages though. You'd have to do some level shifting to get negative ones (and include a negative supply as well). It shouldn't be too hard though.

[FUZZZZzzzz]

http://www.synthrotek.com/products/discontinued-products/16-step-analog-sequencer/