Now apply this to a 7" tall column of gasoline (petrol for you UK'ers & EU
types) with 4 to 8 bit resolution of height (multiple sensors?), filter the
output to compensate for bouncing vehicles and vessels. DO that for $10 and
youu'll be able to retire soon.

Chris

>
> It's actually a pretty simple problem to detect a change in
> an IR light
> source; I'm working on a similar project now that uses a
> reflected beam.
>
> Pulse the beam with a square wave (a 555 timer will do this
> nicely), set up
> a receiver, high pass filter that signal to remove noise from local AC
> sources, then use some sort of switching IC (I'm using the ADG419) to
> demodulate the signal, low pass filter the output to remove
> harmonics and
> add a gain stage and offset stage to set the levels.  It
> could probably be
> even simpler than that for an on/off type switch, but just as
> an idea set,
> there you go!  My current design would work admirably for
> your usage, and it
> has six IC's at about $10 total price.

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