On Mon, 25 Mar 1996, Lauw Lim Un Tung wrote:

> hi all,
> I want to backup SRAM6264 and RTC, but I fail to keep my data for a long
> time. After I checked, the battery voltage was drop below 2 volt in 2 days.
>
>  Vcc 5V -------|>|------------ to Vcc SRAM and RTC
>  (5,3V)       IN60     |              (4,7V)
>                        |
>           --- /\/\-----
>           |   1K       |
>           |----|>|-----
>           |   IN4148
>          ___
>           -  NiCd
>          ___ 3,6 V
>           -  60mAH
>           |
>           |
>          ___
>           -

Try another diode in series with your trickle charge resistor with the
cathode end pointing towards the positive end of the battery.

Page 46 of Feb 96 Circuit Cellar has a good article on this subject if
you can get it. Don...


Don McKenzie donmck@tbsa.com.au
DonTronics Tullamarine, Australia
http://www.labyrinth.net.au/~donmck

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