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<DIV><FONT face=Arial size=2>a) you need at least 2 volts more on the input side
than the output side for these types of regulators to work.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>b) you are trying to get cleaner *power* to the
VCO. This is not what the post is about. Rather, in a VCO design, there will be
a *reference voltage* (usually +5V) that either the integration cap is tied to,
or that the exponential current pair is referenced to. There are many stable +5V
reference chips to choose from, based on price/performance.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Paul S.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=guatis@gmail.com href="mailto:guatis@gmail.com">Benjamín Velasco</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=synth-diy@dropmix.xs4all.nl
href="mailto:synth-diy@dropmix.xs4all.nl">Synth DIY List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, April 10, 2006 12:00
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [sdiy] Voltage references in
VCO</DIV>
<DIV><BR></DIV>
<DIV>Hi list!!</DIV>
<DIV> A few days ago i started a topic about my LFOs affecting the
frequency of my VCOs. Searching the archives i discovered this a very
common problem. Someone here suggested to use on board voltage references in
the VCO rather than using massive decouple in all the other modules. This
makes sense to me because in my synth the only modules that need critically
good supply voltages are the VCOs. So i plan to use lm317/337 in each of my
VCOs. My question is if it is better to connect only the critical points of
the VCOs to the on board refences, or it is enough to use them for the whole
module? I use +-15V. Can i use the lm317/337 to get a cleaner +-15V from
the dirty +-15V or do I need higher voltage at the inputs of the regulators??
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