On 2012-10-18, Thomas Laus <lau...@acm.org> wrote: > Ron: > > I am also using this same board and made a discovery a few years ago > that this backup battery discharges over a period of time, normally > less than a year and is not available when 'really' needing it. There > is a battery charging current available on Pin 3 of your Oncore that > can be used to charge a 1.5F 5.5V Gold Capacitor. I used the Digikey > part P11063-ND for mine. It will mount in the same loacation as the > coin cell. You will need to jumper out R2 (820K) and just connect the > high Farad capacitor between pins 1 & 3 on your Oncore. Watch the > polarity! The charging circuit in the Oncore is current limiting and > it will take about 12H for enough charge to hold the almanac between > powerups. When the capacitor is fully charged, the almanac stays for > about a month. > > You really can't do without a battery. Your almanac information and > current date and time is stored in the Oncore RAM. Your GPS location, > and other parameters get saved in Flash, but the Oncore will require > about 30-40 minutes to recover from a power outage before it can serve > up time again. > Correction!!!!!!
The battery backup charging current is on Pin 1 of the Oncore receiver instead of Pin 3. Pin 3 is tied to ground, but Pin 1 has a current limited 5V available. Tom -- Public Keys: PGP KeyID = 0x5F22FDC1 GnuPG KeyID = 0x620836CF _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
