Since what you are really looking for is the level of reflected light,
then you can simply use an LED to provide light and a [cds cell,
photodiode, LED, etc] to sense the amount of light returning.

Any sensor that outputs light and returns information on how much light
is returning should work.  The few mm sensor should work well, since the
light will travel much better and further inside the tube.

-Adam

Dave VanEe wrote:

>Hey,
>I'm still thinking about how to sense fuel levels in a fuel tank I'm
>building.  I'm leaning toward the idea of a clear shaft tapered at several
>lengths.  Can anyone suggest a cheap way of sensing the reflected light?
>The only cheap sensors I can find appear to have a sensing distance of only
>a few mm at best (I'd be using a ~12" shaft).  Am I looking at the wrong
>type of sensor for this purpose?
>
>Thanks,
>Dave
>
>--
>http://www.piclist.com#nomail Going offline? Don't AutoReply us!
>email listserv@mitvma.mit.edu with SET PICList DIGEST in the body
>
>
>
>
>

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body