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10206Re: Battery Back up for RAM

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  • joshbensadon
    Jun 4, 2012
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      I honestly can't remember, but I think I got at least until the next day. Probably as the battery died, the current dropped when the battery got very low. Well, there's nothing for it but to hook up those old RAM chips and give it a try!

      Does anyone want to wager when the RAM will change? Might be a fun lottery game?

      --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@...> wrote:
      >
      > On 6/3/2012 10:29 PM, joshbensadon wrote:
      > > Hi Lee,
      > >
      > > Remember I told you I put in battery backup for my 2101's?
      > > I just didn't remember where the schematic was for this.
      > > Well, as I was going through my old ELF file, I found the schematic, it was right there in Joseph Weisbecker's article, part 2! PE Sep-1976, pg 39. Using a 9V Battery and a 5.6V Zener diode.
      > >
      > > So how long do you figure my memory would have stayed with a 9V Battery?
      >
      > Probably not all that long. If your 2101's draw 25ma each, that's 50ma.
      > A 9v battery's capacity is probably no more than 500 milliamp-hours,
      > which would support a 50ma load for 10 hours.
      >
      > Now if you used the 2101L it would be longer. And if you used the CMOS
      > 5101, the 9v battery would last almost its shelf life!
      >
      > --
      > Humanity is acquiring all the right technology for all the wrong reasons.
      > -- R. Buckminster Fuller
      > --
      > Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net
      >
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