Hi Bob:
AFAICR on the old 6-channel Motorola GPS boards there was an option for a backup battery. Without the backup battery if
there was any power interruption the memory would erase and you needed to do a cold start. Having the almanac and
ephemeris, even if from a year ago has the effect of greatly reducing start-up time. In this case the purpose of the
super cap is to prevent memory loss because of a power glitch not for long term power failure.
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
Well Q = CV. If delta V = 1 and C = 0.022 then Q = 0.022. That’s 22 ma for 1
second or 22 ua for 1,000 seconds. At 5 ua you would get to about an hour. If
the delta V is 2X that, the times would all double. If the current is 10X lower
than the spec (it might be …) then you could get out to around a day.
Bob
On Nov 1, 2014, at 12:38 AM, Bob Stewart <[email protected]> wrote:
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
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
