[time-nuts] HP Stories: An architectural view of the HP 5060/5061 and awkward oscillator adjustments.

[jimlux]

On 2/25/19 5:48 AM, Bob kb8tq wrote:
> Hi
> 
> Indeed there is both a minimum and a maximum working voltage for a properly derated electrolytic
> capacitor. We found that out in the middle of a design review when the customer’s team brought it
> up … (much to our surprise).
> 
> Bob
> 


The Cornell Dubilier app guide doesn't seem to mention it.
http://www.cde.com/resources/catalogs/AEappGUIDE.pdf

NAVSEA derating guidelines make no mention of it:
https://www.navsea.navy.mil/Portals/103/Documents/NSWC_Crane/SD-18/PDFs/Products/Capacitors/CapacitorsDeratingRevB.pdf

They're both appear to be focused on essentially setting a lower voltage 
as a thermal consideration, and not on a "giving you more margin to 
failure voltage".

https://www.illinoiscapacitor.com/pdf/Papers/reliability_of_capacitors_general.pdf

says you only get a max of twice rated life by derating.  Maybe that's 
because of the "reforming of the dielectric to a thinner layer"..

This is a compendium from 1981 of all sorts of capacitor information but 
doesn't seem to address derating.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810017835.pdf


https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003309.pdf 
has a lot of info on wet slug tantalums..




>> On Feb 25, 2019, at 1:48 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
>>
>> --------
>> In message <CADHrwpcdmyeguXoM69D2byW=DfKwMfi7_t-P=qYst7T7OO=EuA at mail.gmail.com>, Dana Whitlow writes:
>>
>>> This would seem to imply that purposely overrating a 'lyt is pretty pointless.
>>>
>>> Any comments on this notion?
>>
>> I've always wondered that myself, and found very little documentation or
>> wisdom available.
>>
>> As I understand it, even very brief voltage spikes must be kept under the
>> rated voltage, so overrating would buy some transient durability, but
>> other than that...
>>
>> -- 
>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>> FreeBSD committer       | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
>>
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