You may use either a:
CMOS switch set on or off by a pic pin from time to time
or a high impedance input divider( giga ohms) using a FET operational
amplifier conected all the time to the signal.
Vasile


David Dunn wrote:
>
> i have an unknown voltage that will vary from about 0 volts up to about 30, and i need to determine what that voltage
> is via a 16F877 pin.
>
> i know that i could just do a simple voltage divider, put that on a A/D pin and figure it up.
>
> what i'd like to do is find a way to get it without drawing current all the time.
>
> i'm wondering if there's not somethign i could do with a known RC circuit and the PiCBasic POT or RCTIME commands to
> determine what that voltage is .. with this setup i wouldn't be drawing current except when i execute one of those
> commands.
>
> i'll only need to check this voltage every 30 seconds or so.
>
> thanks for any ideas you may have !
>
> david dunn
>
> --
> http://www.piclist.com hint: To leave the PICList
> mailto:piclist-unsubscribe-request@mitvma.mit.edu

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads