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MFOS 16 Step Analogue Sequencer (Now Integrated with Oakley)
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author MFOS 16 Step Analogue Sequencer (Now Integrated with Oakley)
eljay
I have a 'Pure' Oakley system of approximately 20 modules and am planning to extend it with an MFOS 16 step analogue sequencer (self build, 3 PCB variant to include the quantized vari-clock option). The MFOS website does say that all MFOS modules should work with +/- 15V supplies with none or minor modifications.

I am planning to use a spur from my Oakley PSU/Dizzy (I have about 150mA of spare capacity which should be more than sufficient for the approx. 40mA load). I am assuming this should just work but I would appreciate any feedback from anyone who has experience of doing this or advice that would be useful. For example, Tony uses Ferrite beads on every Oakley module (I assume to supress noise), do I need to put ferrite beads in series with the +/- supply lines?

Please note I am an electronics novice but have managed to successfully build all of my 20 Oakley modules largely due to Tony's excellent documentation and products, luckily they have pretty much all worked without error, but I do not have the electronics knowledge to know whether I need to make any modifications.

By the way I'm sure you will all join me in wishing Ray Wilson a speedy recovery from his current ill health.
Synthbuilder
There's no need to add any additional series inductance (via ferrites) to your power wires to the sequencer. The ferrite beads on every Oakley module are a little overkill really. They are there to stop radio frequency interference rather than any noise from connected modules.

So just connect your MFOS modules up to the Dizzy as you would any other module. Remember that Oakley modules separate the 0V supply to the module and panel. You may wish then to connect the ground lugs of all the sockets on the MFOS panel to pin 3 of the Oakley Dizzy power header and not to the module's own 0V connection. The module's 0V (GND) connection would be made to pin 2 on the Dizzy header.

Tony
Zensac
I have built the MFOS 16 step sequencer (Circular layout a la Thomas White) and it runs just fine on 15V alongside Oakley modules.

There's a lot of wirering to be done for the 16 step sequencer, so just be patient and methodical and I'm sure you'll have it up and running in no time.

Good luck!
eljay
I've finally finished my MFOS 16-step analogue sequencer build (with vari-clock option). It is mounted in one of my Oakley racks and is running happily off the Oakley modular PSU (I'm using a spur off the dizzy for each of the three MFOS boards.

I have one problem that I am hoping someone may be able to help with. The vari-clock option allows you to select a quantized step length value between 0 and 15 using a potentiometer to set the value.

Despite calibrating the Step Duration trimmer I am unable to select a step length of 1, it jumps straight from 0 to 2, all subsequent step intervals 3 to 15 can be selected without any problems. Does anyone know if this is an issue resulting from using a +/-15V supply instead of 12V and if so how I can fix it.

Many thanks in advance for any assistance provided.
eljay
After a bit of research (or in my case reading the documentation) I decided to check the clock rate of the vari-clock board as its speed is allegedly important to get right. I measured it and it was 72kHz not the 54Khz stated. I assumed this was probably due to using a +/-15v supply rather than +/-12v. Thankfully the documentation shows a 20k resistor to modify to alter the clock rate, I stuck a 47k trimmer in its place and adjusted until the clock rate was correct. Now everything appears to be working correctly using my Oakley PSU - hurrah.
beatnik
where these sequencer boards can be purchased ?
mumblinstevedubya
mumblinstevedubya
mumblinstevedubya
3rd time lucky!

Try Synthcube
eljay
The boards can be purchased from Soundtronics in the UK and are now back in stock.

I've attached the Schaeffer front panel layout that I designed for the quantised clock option, it requires an extra row of knobs compared with the other layouts I've seen. It is 5U high and 10U in width and I used 19mm moog style knobs throughout. The panel cost approx. £140 but was in my opinion worth it. I also mounted it on a pair of 5u rails to give it rigidity. The pot holes are spaced so that the pots can be mounted on standard vero-board to aid wiring etc.

Soundtronics also provide front panels but I wanted one that matched my existing Oakley panels.
beatnik
thanks for the links, lots of good stuff there
tvh
Thanks for the panel link!
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