Hi Bob et al,
I don't understand the direction this question about the supercap has taken.
It's connected to pin 1 of the GPS receiver. It looks to be a UT+, so that's
the battery backup power. According to my UT+ manual the current draw on this
pin is between 5uA (at 2.5V) and 100uA (at 5V)? How many hours will a .022F
supercap keep at least 2.5V at that sort of discharge rate? Unless the cap has
gone bad, it seems more likely that Bob's comment about it doing a fast survey
and then doing a slower one in the background probably has merit. In fact, my
unit goes through its survey mode pretty quickly on power up. So do those
current/voltage figures imply several hours on the cap?
Bob
From: Bob Camp <[email protected]>
To: Discussion of precise time and frequency measurement <[email protected]>
Sent: Friday, October 31, 2014 9:22 PM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812A GPSDO system
Hi
I sort of doubt that a GPS aux supply is quite that low current. I have seen
some RTC’s that won’t last a month on a coin cell. My recollection is that the
Oncore backup is closer to that category than the “many years on a cap” group.
Bob
> On Oct 31, 2014, at 9:26 PM, Brooke Clarke <[email protected]> wrote:
>
> Hi Bob:
>
> When HP came out with the 300 series Rocky Mountain Basic computers they were
> fitted with a super cap to power the RTC.
> I will keep time for some months.
> http://www.prc68.com/I/HPIB.shtml#300
>
> Mail_Attachment --
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> http://www.prc68.com/I/DietNutrition.html
> Bob Camp wrote:
>> Hi
>>
>> The ultra cap is a pretty small one (physical small). You might be able to
>> find a larger (more farads) one that would fit in the same space. It’s not
>> going to help for a hours and hours sort of outage. It might get you from
>> dying in 15 minutes to dying in a half hour.
>>
>> Bob
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