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<DIV dir=ltr align=left><SPAN class=937463900-16122018><FONT color=#0000ff
size=2 face=Arial>Yes, but it's a little disconcerting that the DG444 (with four
switches) is cheaper than any of the single or dual switches in the DG family,
at least on Digikey. Also, I wonder why the DG445 is slightly more
expensive than the DG444, when the only difference is the logic
polarity.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=937463900-16122018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=937463900-16122018><FONT color=#0000ff
size=2 face=Arial>I'll probably go with two DG444s and one DG417 to get the
nine channels. It would be easier to do eight channels, but my
CV-to-trapezoid converter circuit is naturally geared to 2^n+1 channels.
To avoid channel nine would create complications in the CV circuit. This
was a perfect fit and very elegant with the multiplexers (DG408 and DG409) --
I'm really choked that they don't work well enough.</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Tom
Bugs<BR><B>Sent:</B> Saturday, December 15, 2018 2:58 AM<BR><B>To:</B>
synth-diy@synth-diy.org<BR><B>Subject:</B> Re: [sdiy] Help, I'm Desperate!
(Charge Injection with DG408)<BR></FONT><BR></DIV>
<DIV></DIV>
<P>For single switches try DG417/8/9 <BR>DG417 is SPST NC<BR>DG418 is SPST
NO<BR>DG419 is SPDT</P>
<P>Useful little chips.<BR></P>
<DIV class=moz-cite-prefix>On 14/12/2018 20:09, David G Dixon wrote:<BR></DIV>
<BLOCKQUOTE cite=mid:9040F25BCE0D4A408056B2024B7DEBB3@galvanox01
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<DIV dir=ltr align=left><SPAN class=780350520-14122018><FONT color=#0000ff
size=2 face=Arial>I never have problems with analog electronics. In
the case of this scanner, for example, I designed the analog part so that
there are plateaus in the control voltage when switching occurs, which
gives me about 200mV of slop in the CV for switching.
This circuit worked the very first time (even though I've rebuilt
it three times). The problem here was all digital.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=780350520-14122018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=780350520-14122018><FONT color=#0000ff
size=2 face=Arial>Later today, I'm ordering some DG444 and DG445, and also
some single SPST switches (don't know the DG number yet) and I'm going to
rebuild this thing Roman's way (with a few minor modifiations). The
analog part is perfect and won't have to change at all.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=780350520-14122018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=780350520-14122018><FONT color=#0000ff
size=2 face=Arial>On the digital side, I'm worried about the fact that the
LM3914 comparators do not have built-in hysteresis, and there is no way to
install it, so I'm worried that the comparators will oscillate. I'm
going to stick with LM339, fully rigged for hysteresis (about 10mV worth) as
this worked well. Does anyone here have any experience with
oscillating LM3914?</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Rutger Vlek [<A
class=moz-txt-link-freetext
href="mailto:rutgervlek@gmail.com">mailto:rutgervlek@gmail.com</A>]
<BR><B>Sent:</B> Friday, December 14, 2018 5:36 AM<BR><B>To:</B> David G
Dixon; SDIY List<BR><B>Subject:</B> Re: [sdiy] Help, I'm Desperate!
(Charge Injection with DG408)<BR></FONT><BR></DIV>
<DIV dir=ltr><SPAN style="FONT-FAMILY: Arial; COLOR: rgb(0,0,255)">| It
just shouldn't be this hard.</SPAN>
<DIV><BR></DIV>
<DIV>Ha, I totally agree! I once explored an approach to ring-modulation
using a single VCA and an inverting switch. It seemed like a nice,
cost-effective, approach (especially since I wanted to use a discrete VCA
that would be too bulky for another approach). After two prototypes of
this circuit, I simply gave up. In the analog domain it was simply too
difficult to trigger the switch exactly at the point where the VCA was
fully closed, due to circuit accuracy and noise. It was a hard lesson in
the reality of analog electronics. I went down the route of simply
duplicating the discrete circuit for the negative quadrants, and it works
extremely well albeit not super-linear, but that was a deliberate
choice.</DIV>
<DIV><BR></DIV>
<DIV>Regards,<BR></DIV>
<DIV><BR></DIV>
<DIV>Rutger</DIV>
<DIV><BR></DIV>
<DIV>
<DIV class=gmail_quote>
<DIV dir=ltr>Op wo 12 dec. 2018 om 03:56 schreef David G Dixon <<A
href="mailto:dixon@mail.ubc.ca"
moz-do-not-send="true">dixon@mail.ubc.ca</A>>:<BR></DIV>
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<DIV>
<DIV dir=ltr align=left><SPAN
style="FONT-FAMILY: Arial; COLOR: rgb(0,0,255)">It just shouldn't be
this hard.</SPAN><BR></DIV>
<DIV dir=ltr align=left><SPAN
class=gmail-m_-4428784525104293679608281300-12122018></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=gmail-m_-4428784525104293679608281300-12122018></SPAN> </DIV>
<DIV dir=ltr align=left>
<HR>
</DIV>
<DIV dir=ltr align=left><FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:<A href="mailto:synth-diy-bounces@synth-diy.org" target=_blank
moz-do-not-send="true">synth-diy-bounces@synth-diy.org</A>] <B>On Behalf
Of </B>Roman<BR><B>Sent:</B> Tuesday, December 11, 2018 1:20
PM<BR><B>To:</B> <A href="mailto:synth-diy@synth-diy.org" target=_blank
moz-do-not-send="true">synth-diy@synth-diy.org</A><BR><B>Subject:</B>
Re: [sdiy] Help, I'm Desperate! (Charge Injection with
DG408)<BR></FONT><BR></DIV>
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<DIV>I know it's too late, as the circuit at this stage has already
gone slightly different path, and I already gave up, but couldn't help
drawing this little schemo that explains my idea of using single
switches with that obsoleted chip. Switches should be DG444 or similar
(0=closed, 1=open), or replace diodes with NAND gates and use any
regular dirt cheap switch like 4066.<BR></DIV>
<DIV>There's no switching happening while VCA is open, provided that
VCA control triangles match the edges of LM3914 stages. The only
switched channels are the ones routed to muted VCA, so in theory there
should be no clicking audible.<BR></DIV>
<DIV>Basicaly this is just the circuit that makes this input switching
sequence:<BR></DIV>
<DIV>VCA-A:12233445566..<BR></DIV>
<DIV>VCA-B:11223344556...<BR></DIV>
<DIV>by creating one step overlap between stages. Only 6 inputs in
this example, but can be extended to any other number.<BR></DIV>
<DIV><A href="http://www.synthdiy.eu/files/scanner.png" target=_blank
moz-do-not-send="true">http://www.synthdiy.eu/files/scanner.png</A><BR></DIV>
<DIV><BR></DIV>
<DIV>IMHO switching active channel will always produce some clicking
for many reasons: not matched channels, difference between transistion
times H->L and L->H as Ingo said, break-before-make feature of
DG407, slow response of 4532, and who knows if not also charge
injection.<BR></DIV>
<DIV><BR></DIV>
<DIV>Roman<BR></DIV>
<DIV class=gmail-m_-4428784525104293679nh_extra>
<P>Dnia 11 grudnia 2018 18:24 Ingo Debus <<A
href="mailto:igg.debus@gmail.com" target=_blank
moz-do-not-send="true">igg.debus@gmail.com</A>> napisał(a):<BR></P>
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<DIV id=gmail-m_-4428784525104293679gwpdccd74d0>
<BLOCKQUOTE>
<DIV>Am 11.12.2018 um 08:10 schrieb David G Dixon <<A
href="mailto:dixon@mail.ubc.ca" target=_blank
moz-do-not-send="true">dixon@mail.ubc.ca</A>>:<BR></DIV>
<DIV><BR></DIV>
<DIV>There is now<BR></DIV>
<DIV>only one tiny problem: There is still an almost imperceptible
click when the<BR></DIV>
<DIV>CV crosses 0V (and the logic control voltage crosses 2.5V) in
the positive<BR></DIV>
<DIV>direction. This is when the logic switches from 011 to
100 (i.e., all three<BR></DIV>
<DIV>bits change). Interestingly, I don't hear the click at
all when the CV goes<BR></DIV>
<DIV>in the other direction (100 to 011).<BR></DIV></BLOCKQUOTE>
<DIV><BR></DIV>
<DIV>Couldn’t this still be caused by a very brief „forbidden state“
during the transition from 011 to 100? In your case, the forbidden
state would be 000 (MSBit changes slower that the other two) or 111
(MSBit changes faster). Probably just a difference between rising
and falling slope. Can you check with a scope?<BR></DIV>
<DIV><BR></DIV>
<DIV>Ingo<BR></DIV>
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