Jeff, you can make a homemade capacitive water level
indicator by connecting a vertical plastic tube from top
of tank to bottom of tank so the level in the tube is the
same as water level in tank.  The tube has 2 narrow strips
of foil running up the sides of the tube, forming a capacitor
of sorts. Water in the tube changes the dielectric constant
of the capacitor, which changes the total capacitance, which
can be read with external circuitry.

Somewhere in the last month I found a site that describes
exactly what you are doing, with a stamp.
I suspect it was somewhere at Tracy Allens site:
<http://www.emesystems.com/BS2index.htm>

I've been considering a similar thing, using a stamp to
monitor water level, battery voltages, and fridge functions
including inside and outside temperature, auto-relight if
the propane fridge goes out, and possibly "optimizing"
the flame size to always provide the optimum temperature
in the heater chamber for best performance.

I wish I could figure a good way to monitor the propane
level and display it....

I've got a 2 x 16 LCD panel,  keypad, BS2, and some
temperature sensing bits set aside for the task, I just
need to get another large project out of the way first.

Pmail me if you wanna talk about stamp stuff and
the possiblitiy for use in a Vanagon.
I'll probably add some burgler alarm features if I have
enough inputs and code space left over. Since the
stamp can output DTMF tones, it's even easy to add
an auto-dialer to summon help if your Westy is being
violated.....

Steve
EJ22 -> '86 Westy "Escape Pod"

--------------------------------------
>Hello,
>  Has anyone come up with a better water level sensor for the westy
>holding tank? I'm looking for something that will tell me how many
>gallons I have, not just that its "almost full", "in-between", or
>"empty". I'm thinking either a float-type resistance sender, like a fuel
>sender, or maybe a capacitance probe. It'll interface with a basic stamp
>and LCD screen, to take the place of the LED panel that's there now.
>
>While I'm working on that, I'm going to make a water level alarm that
>beeps outside the van when the water tank is full, so I can stop filling
>before filling it all the way up and having it leak out the filler tube.
>Anybody done that?
>
>Cheers,
>  Jeff