[sdiy] Ken stone's synthacon filter

[Karl Ekdahl]

I do have the pulldowns and the 4066 is running from
GND0 to 9v so that should be fine, right? I used the
4066 and the SPST because i tried using the same parts
for everything, i'm using this technique troughout all
of my synthesizer, and it seems to work out fine...

I should probably measure all the resistor values (as
someone suggested, thanks) and see if i can find
anything. Is there any simple way to measure
capacitors with an multimeter that doesn't really do
that? I guess transistors are more or less just not
possible to measure while built in to a circuit...

thanks all

karl

 --- Peter Grenader <peter at buzzclick-music.com> skrev:

> This is (sort of) how Nyle Steiner did it.- but he
> used a rotary and no
> analog switch behind it.  I take it you're using the
> analog switch to back
> up the normal on (off) on switch you're using to
> drive it.    If you're not
> mixing setting up mixed modes you should be able to
> just use a NKK (C&K
> makes one, too)  three position mechanical toggle. 
> They are a little pricey
> (about $5 USD), but you won't need the 4066 and a
> bunch of voodoo that could
> come with that.
> 
> Speaking of which - what are you running the 4066
> from? Remember the 4066
> can't handle anything more than an 18 volt swing
> from its neg and pos rails,
> You have to step the power down to that part to +/-
> 9 volts max. And...I
> don't believe you can switch anything through that
> that exceeds that range,
> either, yes?  I think.
> 
> You can also consider a MAXIM analog switch - they
> will run on full VCC
> without problems.  There are a few other
> manufacturers who make full range
> switches.  But I go with MAX because their sample
> policy rules.
> 
> - P
> 
> Karl Ekdahl wrote:
> 
> > I found something very strange in my circuit; i
> use a
> > SPST switch and a 4066 + 4001 to select HP, BP or
> LP
> > mode. That is configured something like this (bad
> > ascii art coming up):
> > 
> > / o---o------------o HP (to 4066)
> > +9v ----o/ SPST |
> > o-o--------------o LP (to 4066)
> > | |    ___
> > | o---\   `.
> > |     | NOR >--o BP (to 4066)
> > o-----/___,´
> > 
> > 
> > and then delivered the signal through the 4066 to
> the
> > VCF. The thing is that starting of at the BP mode
> (no
> > switch active) works. But while switching to
> another
> > mode, there's a loud *click* and the circuit dies.
> > Switching back to BP mode and direct-injecting a
> > high-level signal into the circuit makes it run
> again.
> > Being in LP or HP mode and direct-injecting
> doesn't
> > give any results whatsoever. Funny thing is that
> it
> > also died while turning of my soldering iron and i
> > made it take in radio as well.
> > 
> > Any thoughts?
> > 
> > thanks
> > 
> > Karl
> > 
> > 
> > --- Magnus Danielson <cfmd at bredband.net> skrev:
> >> From: Karl Ekdahl <_nial_ at yahoo.com>
> >> Subject: RE: [sdiy] Ken stone's synthacon filter
> >> Date: Sat, 11 Sep 2004 19:42:35 +0200 (CEST)
> >> Message-ID:
> >>
> <20040911174235.75686.qmail at web52905.mail.yahoo.com>
> >> 
> >> Karl,
> >> 
> >>> No, no that's not what i mean. I do have a
> faulty
> >>> connection somewhere but i don't understand crap
> >> of
> >>> VCF theory so i need some directions to be able
> to
> >>> find the component(s) that are making trouble..
> >> 
> >> Almost any point you are going to sniff in the
> >> Synthacon filter requires a
> >> high-impedance probe, or else you are loading it
> to
> >> much.
> >> 
> >> The Synthacon filter works "backwards" to how
> normal
> >> filter works, so if you
> >> feel confused, you are probably not alone. It's
> >> really not that hard to explain
> >> with a bunch of math, but I spare you the
> >> derivations (this time).
> >> 
> >> Try insert signal at different places. Look at
> the
> >> feedback loops. Is there a
> >> high DC-component in there for instance? You
> could
> >> have a DC-leakage problem.
> >> Etc. etc. You might have forgoten a little link
> >> somewhere.
> >> 
> >> Cheers,
> >> Magnus - trying to do something without the
> >> schematic in hand
> >> 
> >>> /Karl
> >>> 
> >>> --- "James R. Coplin" <moog at qwest.net> skrev:
> >>>> The output on my Cyndustries version is really
> >> low
> >>>> as well. Must be a design
> >>>> thing.
> >>>> 
> >>>> James R. Coplin
> >>>> ***************
> >>>> If anyone asks of my whereabouts,
> >>>> simply tell them i've gone out the window
> >>>> for a spot of tea and am not
> >>>> expected back any time soon.
> >>>> ***************
> >>>> 
> >>>>> -----Original Message-----
> >>>>> From: owner-synth-diy at dropmix.xs4all.nl
> >>>> [mailto:owner-synth-
> >>>>> diy at dropmix.xs4all.nl] On Behalf Of Karl
> >> Ekdahl
> >>>>> Sent: Saturday, September 11, 2004 10:55 AM
> >>>>> To: synth-diy at dropmix.xs4all.nl
> >>>>> Subject: [sdiy] Ken stone's synthacon filter
> >>>>> 
> >>>>> Hi all, i'm having some trouble with Ken
> >> Stone's
> >>>>> synthacon..  The thing is that the output is
> >>>> really
> >>>>> low and noisy sometimes, and sometimes it's
> >> clean.
> >>>>> Apparently a bad part and/or cable, but if
> >> anyone
> >>>>> could supply me with any basic testpoints and
> >> what
> >>>>> reading i *should* get i might not have to
> >>>> completely
> >>>>> re-solder the whole unit...  I tried following
> >> the
> >>>>> schematic and measure different points with my
> >>>> scope,
> >>>>> but i get nothing at all (i have an old scope
> >> and
> >>>> no
> >>>>> probe). Any ideas anyone?
> >>>>> 
> >>>>> Karl
> >>>>> 
> >>>>> Höstrusk och grå moln - köp en resa till solen
> >> på
> >>>> Yahoo! Resor på adressen
> >>>>> http://se.docs.yahoo.com/travel/index.html
> >>>> 
> >>>> 
> >>>> 
> >>>> 
> >>>> 
> >>> 
> >>> Höstrusk och grå moln - köp en resa till solen
> på
> >> Yahoo! Resor på adressen
> >> http://se.docs.yahoo.com/travel/index.html
> >> 
> >> 
> > 
> > Höstrusk och grå moln - köp en resa till solen på
> Yahoo! Resor på adressen
> > http://se.docs.yahoo.com/travel/index.html
> > 
> 
>  

Höstrusk och grå moln - köp en resa till solen på Yahoo! Resor på adressen http://se.docs.yahoo.com/travel/index.html