[sdiy] CEM3340: VCC +10V vs +11V

[Tim Ressel]

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.

--TimR


On 6/6/2016 6:06 AM, bbob wrote:
> The original spec is for nominal 15v (max 18v) supplies.  Nor clear 
> why you'd drop to 12?
>
> On Mon, Jun 6, 2016 at 6:58 AM, Tom Wiltshire <tom at electricdruid.net 
> <mailto:tom at electricdruid.net>> wrote:
>
>     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.
>
>     On 6 Jun 2016, at 11:00, Florian Anwander
>     <fanwander at mnet-online.de <mailto:fanwander at mnet-online.de>> wrote:
>
>     > You are right.
>     >
>     > I got meanwhile also an answer from Dieter (english translation
>     by me):
>     >
>     > "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).
>     > 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."
>     >
>     > Florian
>     >
>     > Am 06.06.2016 um 11:00 schrieb Vladimir Pantelic:
>     >>
>     >>
>     >> On Jun 6, 2016 10:38 AM, "Florian Anwander"
>     <fanwander at mnet-online.de <mailto:fanwander at mnet-online.de>
>     <mailto:fanwander at mnet-online.de
>     <mailto:fanwander at mnet-online.de>>> wrote:
>     >> >
>     >> > What might be the reason to run the 3340 at a lower VCC?
>     >>
>     >> I see a 7810 regulator on the PCB, so I'd guess they wanted
>     additional stabilization for the chip's supply voltage
>     >>
>     >
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-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com

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