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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
MFOS sequencer ext clock
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djrevmoon



Joined: May 05, 2009
Posts: 9
Location: almere

PostPosted: Mon Feb 27, 2012 5:18 am    Post subject: MFOS sequencer ext clock Reply with quote  Mark this post and the followings unread

Hi all,

I cant get the external clock input to work on my MFOS 16-step sequencer. If I short the input to ground, it will advance a step, but if I hook up an LFO (with a diode to cut out the neg part), it wont budge. R18 and R23 are the correct values, and the LFO gives a high enough voltage to trigger the clock. Any ideas?
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iopop3



Joined: May 28, 2010
Posts: 94
Location: Malmö, Sweden

PostPosted: Tue Feb 28, 2012 12:20 am    Post subject: Reply with quote  Mark this post and the followings unread

I think I read somewhere that the external clock needs to be near v+. An LFO would most likely put out a signal between +-5v. There used to be a schematic on how to adapt the input signal on the mfos site, cant seem to find it now.
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djrevmoon



Joined: May 05, 2009
Posts: 9
Location: almere

PostPosted: Tue Feb 28, 2012 3:44 am    Post subject: Reply with quote  Mark this post and the followings unread

iopop3 wrote:
I think I read somewhere that the external clock needs to be near v+. An LFO would most likely put out a signal between +-5v. There used to be a schematic on how to adapt the input signal on the mfos site, cant seem to find it now.


I'll check the output of the LFO, good call. Thanks!
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Juxwl



Joined: Nov 25, 2011
Posts: 6
Location: Iowa, USA

PostPosted: Sat May 12, 2012 10:17 am    Post subject: Reply with quote  Mark this post and the followings unread

I run my clock signal through a VCA and crank the gain up and it works great. The clock signal needs some pre amplification.
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djrevmoon



Joined: May 05, 2009
Posts: 9
Location: almere

PostPosted: Sat May 12, 2012 1:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

good idea, i'll try that.....
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NoizeToyz



Joined: Jan 09, 2010
Posts: 24
Location: Brighton
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PostPosted: Thu Aug 02, 2012 3:56 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey!
How did you get on with this? I also have a question about the voltage needs of the ext clock input of the 16 Step seq;

I use the little Doepfer MSY2 to drive the sequencer in my SH101 (which works great), however it doesn't seem to drive the MFOS 16 Step. I guess this is something to do with it not outputting a strong enough voltage?

The manual says that the MSY2 outputs "... a periodic TTL signal (0/+5V) representing the tempo" - do you think this needs to be boosted to -/+ 15v ?

http://www.doepfer.de/pdf/msy2_man.pdf

Anyone got a little circuit that could do this?

Thanks!
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NoizeToyz



Joined: Jan 09, 2010
Posts: 24
Location: Brighton
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PostPosted: Thu Aug 02, 2012 4:47 am    Post subject: Reply with quote  Mark this post and the followings unread

Just found this schematic on Ray Wilson's site - could this be the answer?
Seems to convert low voltage inputs (like line/instrument level) to gate (which I'm guessing is -/+12v

http://www.musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=OLDIESBUTGOODIES/CONTROLLERS/audiotogate.html&VPW=1430&VPH=649
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NoizeToyz



Joined: Jan 09, 2010
Posts: 24
Location: Brighton
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PostPosted: Thu Aug 02, 2012 7:21 am    Post subject: Reply with quote  Mark this post and the followings unread

Just had a reply from the man himself; Ray suggests this circuit to boost low voltage gates and clock sources.

http://www.musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=HOT_TIPS/gate_buffer.html&CATPARTNO=
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NoizeToyz



Joined: Jan 09, 2010
Posts: 24
Location: Brighton
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PostPosted: Thu Aug 02, 2012 10:51 am    Post subject:   Reply with quote  Mark this post and the followings unread

I just breadboarded that design above and can confirm it works for boosting the level between a Doepfer MSY2 (and the Doepfer A-190 Eurorack MIDI-CV Interface).

It also works with the Wogglebug LFO output (which it didn't before).
And I tested it with the square wave output of the Doepfer A-145 LFO - all good.

Nice.
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himijendrix



Joined: Apr 16, 2012
Posts: 18
Location: Germany

PostPosted: Thu Mar 19, 2015 10:00 am    Post subject: Reply with quote  Mark this post and the followings unread

A quick and simple solution I used on the clock input of my 16 Step Sequencer is just a N-Channel Mosfet and a Pulldown Resistor (~10k).
It will accept any Input Clock Signal that exceeds the treshhold voltage (typically 2-3V).

The Disadvantage (!):
It will only trigger the the step when voltage rises from LOW to HIGH. So you need a trigger input. If you apply a gate signal that lasts for one note, the sequencer will step after the note was played.

I'm wondering why Ray didn't design it more compatible. You should at least be able to trigger your MFOS Sequencer with your MFOS Synthesizers...


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