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<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 type="cite"
cite="mid:9040F25BCE0D4A408056B2024B7DEBB3@galvanox01">
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<div dir="ltr" align="left"><span class="780350520-14122018"><font
size="2" face="Arial" color="#0000ff">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
size="2" face="Arial" color="#0000ff">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
size="2" face="Arial" color="#0000ff">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>
<blockquote style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT:
5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px" dir="ltr">
<div dir="ltr" class="OutlookMessageHeader" lang="en-us"
align="left">
<hr tabindex="-1"> <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>
<blockquote style="BORDER-LEFT: rgb(204,204,204) 1px
solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class="gmail_quote">
<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>
<blockquote style="BORDER-LEFT: rgb(0,0,255) 2px
solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px;
MARGIN-RIGHT: 0px" dir="ltr">
<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>
<blockquote style="BORDER-LEFT: rgb(153,153,153)
2px solid; MARGIN: 0px; PADDING-LEFT: 8px"
class="gmail-m_-4428784525104293679nh_quote">
<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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