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 <b...@evoria.net> 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 <kb...@n1k.org> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > 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 <bro...@pacific.net> 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 -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
