[sdiy] help getting VCO levels down to MN32XX BBD size

[David G. Dixon]

OK, Dan, I don't profess to understand this circuit (I haven't tried using
BBDs or PLLs yet), but I think I can offer some advice about your finicky
bias:

Don't try to set a bias by putting a trimmer between two rails.  Pretend you
can get the exact voltage you want with a divider (i.e., two specific
resistors), build that divider, and then put a small-value trimmer in
between.  Then the trimmer won't be too touchy.

For example, if you need 5.2V and your rails are 9V and 0V, then you need
two resistors in a ratio of 3.8/5.2.  22k/30k would work nicely.  Then, put
a 2k trimmer in between and take your bias from the tap.  The trimmer will
now have a range of 5V to 5.33V.  If it's a multi-turn trimmer, then you
should be able to find your magic bias point easily.
 

> for further refrence you could look at the MN3207 zombie chorus
> 
> 
> http://www.synthdiy.com/files/2007/zombie_chorus_mn3207_based.jpg
> --------------------------------------------
> check out various dan music at:
> 
> http://www.myspace.com/lossnyc
> 
> (updated monthly)
> 
> http://www.soundclick.com/lossnyc.htm
> 
> 
> 
> http://www.indie911.com/dan-snazelle
> 
> (or for techno) http://www.myspace.com/snazelle
> 
> ALSO check out Dan synth/Fx projects:
> 
> AUDIO ARK:
> 
> www.youtube.com/watch?v=TJRpvaOcUic
> 
> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
> 
> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
> 
> and soundtrack/design work:
> 
> NEW: check out Dan's sound design from the 1998 award winning film SAFARI
> by catherine chalmers
> 
> http://www.catherinechalmers.com/videos.cfm
> 
> 
> 
> 
> 
> 
> ----------------------------------------
> > Date: Sat, 12 Sep 2009 18:00:22 -0700
> > From: dixon at interchange.ubc.ca
> > Subject: RE: [sdiy] help getting VCO levels down to MN32XX BBD size
> > To: subjectivity at hotmail.com; guitaricon at verizon.net; synth-
> diy at dropmix.xs4all.nl
> >
> > All Ken Stone's module does to the synth level output is attenuate it by
> a
> > factor of 22 across a divider and send it to the effect, and then re-
> amplify
> > the signal from the effect by the same factor in a non-inverting opamp
> and
> > send it back into the synth. There are some ac coupling capacitors and a
> > few other bells and whistles, but basically its pretty simple. I don't
> know
> > why this wouldn't work for what you want to do.
> >
> > Also, I don't understand what you mean by "adding the proper bias". What
> is
> > this bias, and why do you need to add it? Does the flanger output have a
> dc
> > component (i.e., is it not centred about 0V)? Granted, I couldn't make
> > heads or tails out of your "back o' the napkin" schematic, so there's
> > probably something I'm missing.
> >
> >
> >> not sure if that will work stock as that is for using LINE with an
> effects
> >> chain. (i think that is why there is a 1m to ground)
> >>
> >> that is not my intention.
> >>
> >> i want to solder this up as a module for my modular
> >>
> >>
> >> also, I am interested in how I need to modify any filtering for a line
> >> level.
> >>
> >> the main issues i have had so far with trying to use a simple neg gain
> and
> >> offset opamp is that unless I add the proper Bias, it does not seem to
> >> work with the rest of the circuit.
> >>
> >> maybe I need to just keep trying things!
> >>
> >> thanks
> >>
> >>
> >>
> >> ----------------------------------------
> >>> From: guitaricon at verizon.net
> >>> To: synth-diy at dropmix.xs4all.nl
> >>> Subject: Re: [sdiy] help getting VCO levels down to MN32XX BBD size
> >>> Date: Sat, 12 Sep 2009 19:41:24 -0400
> >>>
> >>> Ken Stone's Stomp Box Adapter?
> >>>
> >>> http://www.cgs.synth.net/modules/cgs60_sba.html
> >>>
> >>>
> >>>
> >>> ----- Original Message -----
> >>> From: "Dan Snazelle"
> >>> To:
> >>> Sent: Saturday, September 12, 2009 7:19 PM
> >>> Subject: [sdiy] help getting VCO levels down to MN32XX BBD size
> >>>
> >>>
> >>>>
> >>>>
> >>>>
> >>>> i got a very basic flanger working
> >>>>
> >>>> http://electro-music.com/forum/phpbb-
> >> files/snazzy_simple_test_flanger_162.jpg
> >>>>
> >>>> however it only works with Guitar signals
> >>>>
> >>>> In order to get it to work with +/- 10 volts and +/- 5volt signals,
> >> what
> >>>> can I add to the front end??
> >>>>
> >>>> in most cases I would just level shift, etc But this signal needs to
> be
> >>>> TINY (lets say .50 volts peak to peak)
> >>>>
> >>>> so far I cant find anyone that does this without a compander.
> >>>>
> >>>> any ideas, schematics or links appreciated
> >>>>
> >>>>
> >>>> thanks so much
> >>>>
> >>>>
> >>>>
> >>>> --------------------------------------------
> >>>> check out various dan music at:
> >>>>
> >>>> http://www.myspace.com/lossnyc
> >>>>
> >>>> (updated monthly)
> >>>>
> >>>> http://www.soundclick.com/lossnyc.htm
> >>>>
> >>>>
> >>>>
> >>>> http://www.indie911.com/dan-snazelle
> >>>>
> >>>> (or for techno) http://www.myspace.com/snazelle
> >>>>
> >>>> ALSO check out Dan synth/Fx projects:
> >>>>
> >>>> AUDIO ARK:
> >>>>
> >>>> www.youtube.com/watch?v=TJRpvaOcUic
> >>>>
> >>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
> >>>>
> >>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
> >>>>
> >>>> and soundtrack/design work:
> >>>>
> >>>> NEW: check out Dan's sound design from the 1998 award winning film
> >> SAFARI
> >>>> by catherine chalmers
> >>>>
> >>>> http://www.catherinechalmers.com/videos.cfm
> >>>>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Synth-diy mailing list
> >>>> Synth-diy at dropmix.xs4all.nl
> >>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >>>
> >>> _______________________________________________
> >>> Synth-diy mailing list
> >>> Synth-diy at dropmix.xs4all.nl
> >>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >>
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at dropmix.xs4all.nl
> >> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >