quattro digest, Vol 1 #2998 - Radio Power w/battery disconnect

[Larry C Leung]

A diode would do the job, I still just wonder whether or not 9V is
sufficient to keep the logic circuits of the memories going. If so, it's
a $5 job.

LL - NY

On Fri, 22 Feb 2002 14:42:40 -0500 Huw Powell <audi at mediaone.net> writes:
>
>> Assuming that the cigarette lighter is non-switched, supplying the
>lighter with a power plug that has a 12 source in it would keep the
>radio memory. It would actually be interesting to see if the
>electronic memories (and clock and ECU memory) could be supported by
>something easier, say 9V or if needed, two 9V in parallel. If so, run
>to Radio Shack, buy one of those cigy lighter sockets and a couple of
>9V battery snaps and a couple of 9V batteries, wire the ground (cigy
>lighter shell half) of the 9V to negative of the 9V's, the center to
>the + side, voila!, non-volatile radio memory when you need to pull
>the battery. Total cost, about $5. Of course, the question is, will 9V
>hold the memory?
>>
>> Note, be careful if this is the set-up. Until the battery is
>disconnected, it will TRY to re-charge the 9V batteries at 12V. This
>may cause a problem for 9V batteries that can't be recharged. Too bad
>there aren't any small 12 batteries that have a little real current
>(photo batteries just don't have enough).
>
>Probably easier and cheaper to just buy one.  The "product" should
>have
>a diode in it to prevent the attempted 12v charge of the 9v battery.
>
>I picked one up, but all I have to worry about are radio station
>presets, so half the time I forget to use it anyway, and the other
>half
>I can't remember if it worked!
>
>--
>Huw Powell
>
>http://www.humanspeakers.com/audi/
>
>http://www.humanthoughts.org/