MFOS 16 step rotary sequencer panel wiring and build log

[hallvard]

Sorry if this is already out there, but I couldn't find anything in my searches:

Has anyone drawn up a sketch for the wiring of this type of sequencer? I am making a version with the Thomas White type rotary design (slightly customized). I guess the changes from the MFOS design are not huge, but I thought I'd ask in any case.

If anyone is interested I have added the fpd file. All credit for the original design to Thomas White (naturalrhythmmusic.com) for the rotary layout and Ray Wilson of musicfromouterspace.com for the sequencer design. The fpd layout is made starting from a file I found at: http://www.electro-music.com/forum/topic-37292.html. I have customized the holes in some places and width of the panel, so go through everything if you would like to use this...

[ashleym]

It was me posting on the other link.

What are you not sure about? The wiring of the pots or the sockets etc?

[sduck]

Go here - http://www.musicfromouterspace.com/anal ... 6_2006.php

Everything you should need to know is there. There are no changes from this circuit with this panel design.

[hallvard]

Cheers for that file ashleym!

Yes, thanks sduck - I know everything is there at Ray's site, I was just wondering if anyone had bothered drawing the wiring for the new layout. I like to follow a sketch while doing the wiring as all my mistakes so far (I'm a beginner) have been from bad wiring. Even if it's just a rearrangement of the components, it could lead to me messing up.

In any case since I am waiting for my panel I have started to draw it up and will post it when it's finished. It'll look like a mess, but maybe someone else is curious at some point...

[sonicwarrior]

all my mistakes so far have been from bad wiring.

It might help to label the pots, jacks & switches on the solder side with a waterproof marker. E.g. 12C for 'Channel 12, coarse pot'.

[hallvard]

It might help to label the pots, jacks & switches on the solder side with a waterproof marker. E.g. 12C for 'Channel 12, coarse pot'.

Good tip - I'll make sure to do that.

Just finished my drawing (I think), but have to do some proofreading tomorrow. It looks messy but at least I have thought through the wiring a bit now so should be more prepared . I have one question though - how do I wire up the glide jack? Didn't immediately see that in Ray's drawing - is that something Thomas White added later?

EDIT:
Just read over the schematic at the MFOS site again and saw it now ... CV1 is the one influenced by glide/portamento. Fixed the drawing.

EDIT:
Oops - need to reverse the numbering and wiring of the pots... or just keep it anti-clockwise. Updated now in v3.

EDIT:
Diodes were wrong way around - fixed in v4.

[delayed]

Do you mean the 'portamento' pot? If so, it is on the panel wiring top left R51-3 /R51-1&2

[ashleym]

This will be too late in the day but I made up this sequencer with one set of pots and a range switch. So when I am doing pitch critical sequences rather than control voltage sequences, if you see what I mean, I switch the voltage range to 2.5V. This give plenty of resolution in the pots range. I also built Rays quantiser into the panel. This corrects the voltage for each step to a musical pitch.

Do you think having the step switches in a different place to their corresponding step pot works? I can't get my head round it working. I stuck to 2 rows of 8 pots. This matches my other modules as well.

I only offer this as food for thought and absolutely not a criticism. I look forward to your results!!

[hallvard]

Do you mean the 'portamento' pot? If so, it is on the panel wiring top left R51-3 /R51-1&2

No, I probably didn't explain very well but I meant the CV out jack affected by portamento. On the MFOS panel wiring drawing there are CV1-CV3, so I first assumed these were all just the same CV out, but looking at the circuit diagram and reading the text I saw that CV1 was affected by the portamento pot, so that would be the one to wire up the the glide output jack.

So when I am doing pitch critical sequences rather than control voltage sequences, if you see what I mean, I switch the voltage range to 2.5V. This give plenty of resolution in the pots range.

Nice idea! I saw some posts on this, probably yours, before I ordered the panel, but I decided I'd try this way first. I am also planning on building/buying a quantizer later. Any recommendations? Was thinking of getting the Doepfer A-156 quantizer and the A-199 reverb module so I'll get a small eurorack started as well.

Do you think having the step switches in a different place to their corresponding step pot works? I can't get my head round it working.

Maybe I don't understand your question, but as far as I can see the switches could be anywhere? They are just wired to the digital board and close/open the connection to the U5 output pins.

I only offer this as food for thought and absolutely not a criticism. I look forward to your results!!

Thanks for your comments and for showing interest! Even more fun to build stuff when someone cares .

[home_listening]

I finally got around to finishing my MFOS 16 stepper off, this was my first DIY project from a while ago now that somehow evaded completion. I'm a crappy woodworker, but it is at least solid. 54cm wide, Serge panel in the 2nd shot as a size comparison.





The documentation is second to none, it all ports easily to layouts other than the one provided.

[hallvard]

Cool! I like those sliders. Congrats on finishing. Yeah the documentation is definetely excellent. I think I'm pretty much set for soldering when my panel finally arrives (Fedex says "on vehicle for delivery" at the moment!).

[home_listening]

Thanks, I plan on using this mostly in audio frequency as a 'drawable' waveform oscillator. I've almost finished a reciprocal module which contains:

-A high speed 1/v oct oscillator to control the clocking
-1/v oct scaled slew, to smooth out the stepping effect
-A quantizer, can be used to condition the CV coming in when being used as an oscillator or to condition CV coming out when being used as a sequencer.

All this connects to the modular with a DB-25, connects to a module in my 4U.

[ashleym]

Maybe I don't understand your question, but as far as I can see the switches could be anywhere? They are just wired to the digital board and close/open the connection to the U5 output pins.

Yes they can be anywhere but I find it makes sense to me to have the switch next to the pot so I know exactly which step I am switching on and off. Look at the layout above for a good example.

[hallvard]

Aha, I get what you mean. I'll hopefully get used to it pretty quickly

[hallvard]

Got the panel from Schaeffer yesterday! A bit pricy but very happy with it. One thing to note is that 24 mm pots are too big, so need to use something like 16 mm for the inner circle (fine pots).



Hoping for some progress this weekend!

[sduck]

You could always drill out the holes so that the 24mm pots will fit.

[hallvard]

The shafts fit, but there's not enough room behind the panel for the pot bodies. At least not with the solder lugs towards the center. I'll probably need the 24 mm ones for something else later.

[hallvard]

Update on my build. Sorry if this is of no interest but I like these threads myself, so hopefully someone else will enjoy it . The boards are stuffed except for ICs (and the wall wart supply board is not started yet).





The worst of the wiring is done, but I am waiting for some smaller (16 mm alpha) pots for the fine tuning circle and for some 1/4" jack sockets. I had bought some LED holder clips, but I really didn't like using them so ended up first gluing a couple directly. That was kind of tiresome so I ended up holding the LEDs in place with double sided tape. It is really sticky so I think it'll hold. If not I'll just glue them in later.

Really looking forward to powering this up! Hurry up postmen around the world and get those shipments to Norway .

[hallvard]

Finished up the 16 step sequencer yesterday, and made a quick mock-up "case" for it today. Need to find something nice to put it in soon.

Pretty happy with the build as it is actually outputting voltages . I switched up the CBUS and RIN wires (going to the anode leads of the step LEDs and the rate LED) so the step and rate LEDs didnt work at first but now the step LEDs do after fixing that. The rate LED does not however, so I may need to change that. Also it seems like some of the steps are "slow" in that the voltage is changed slowly and on some "rounds" it jumps over it completely.... Makes it more random than I would like.

Anyways a few quirks are expected and then I'll have something to work on which is where I tend to learn stuff, so that's all good! Hoping for some help later unless this is a quick fix tomorrow after I get some sleep.

[ashleym]

Great job. Lovely neat wiring. Looking forward to hearing it/her/him in action. I like build threads too, this is the synth DIY forum and not just the PCB selling one.

Is that an ultimate in the background?

Did you get a little pin hole cut out next to the rotary switch to give it a better grip when you turn it, it's hard to tell from the photos? Or don't your switches have them?

[hallvard]

Thanks ashleym! Was getting worried I'd get banned for spamming to myself here

That is indeed the ultimate + expander in the background. Was my first real DIY build (after a noise toaster) and I was in a hurry to get it done so the wiring is a bit messier there, hehe. Works great now, though. I took my time with the wiring on this sequencer, so it turned out pretty well (of course messier than the picture up there which is only partially completed).

I didn't get a pin hole cut out for the rotary switches but I probably should have! So far it works ok, but it would probably feel sturdier with one. Did you do it with yours? Yours look great by the way! Had a look at electro-music. Do you have more pics on here?

Off to see what kinks I need to iron out

I have also started looking at getting a quantizer and some reverb module for my system. And maybe do the vari-clock add-on soon. Yeah I've got the bug bad. Looking forward to resting and playing with this as is for a while though!


EDIT:
Turns out the sequencer works perfectly (the basic stuff like stepping through the voltages and gate output). It was just some weird delay on my computer that messed up the timing somehow. A restart fixed it.