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<p>A good linear regulator will provide isolation from power supply
fluctuation, although you pay for it in reduced headroom. An LDO
(low dropout) regulator will get some headroom back. The 78xx
series is a very old design and may not be the best choice for
running a VCO. <br>
</p>
<p>--TimR<br>
</p>
<br>
<div class="moz-cite-prefix">On 6/6/2016 6:06 AM, bbob wrote:<br>
</div>
<blockquote
cite="mid:CABbX2d8EgWDju313YmUvT1uGeLSJ0KYWCdtdb2Qq7BrvjSCD3g@mail.gmail.com"
type="cite">
<div dir="ltr">The original spec is for nominal 15v (max 18v)
supplies. Nor clear why you'd drop to 12?
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Jun 6, 2016 at 6:58 AM, Tom
Wiltshire <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:tom@electricdruid.net" target="_blank">tom@electricdruid.net</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">If you
were designing with it now (which it looks like we could
realistically do) then you could run a +/-15V power
supply, with +12V for the VCOs. That'd give you the best
of all worlds - headroom and stability.<br>
<br>
On 6 Jun 2016, at 11:00, Florian Anwander <<a
moz-do-not-send="true"
href="mailto:fanwander@mnet-online.de"><a class="moz-txt-link-abbreviated" href="mailto:fanwander@mnet-online.de">fanwander@mnet-online.de</a></a>>
wrote:<br>
<br>
> You are right.<br>
><br>
> I got meanwhile also an answer from Dieter (english
translation by me):<br>
><br>
> "We use 10V for the CEM3340, in order to achieve an
even better stability (if the + 12V would vary slightly,
the internal 10V on the module still are stable). But we
had always problems, because obviously not all CEM3340
worked properly with 10V(even if the datasheet indicated
so).<br>
> In the last production series of the A-111-1, we
bridged 7810and operated the CEM3340 directly on 12V. The
A-100PSU2 was so stable that there were no problems here."<br>
><br>
> Florian<br>
><br>
> Am 06.06.2016 um 11:00 schrieb Vladimir Pantelic:<br>
>><br>
>><br>
>> On Jun 6, 2016 10:38 AM, "Florian Anwander" <<a
moz-do-not-send="true"
href="mailto:fanwander@mnet-online.de"><a class="moz-txt-link-abbreviated" href="mailto:fanwander@mnet-online.de">fanwander@mnet-online.de</a></a>
<mailto:<a moz-do-not-send="true"
href="mailto:fanwander@mnet-online.de">fanwander@mnet-online.de</a>>>
wrote:<br>
>> ><br>
>> > What might be the reason to run the 3340 at
a lower VCC?<br>
>><br>
>> I see a 7810 regulator on the PCB, so I'd guess
they wanted additional stabilization for the chip's supply
voltage<br>
>><br>
><br>
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<pre class="moz-signature" cols="72">--
--Tim Ressel
Circuit Abbey
<a class="moz-txt-link-abbreviated" href="mailto:timr@circuitabbey.com">timr@circuitabbey.com</a></pre>
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