z axis feed back for under a dollar? - variable capactive-> freq-> mic

[Aztecphoenix]

OK, don't paint the strip with varnish, then might I suggest a strip of aluminium tape covered with a layer of packing tape but use varnish around the edge of the packing tape to seal it from the water, if laid out carefully it should be very accurate.

do this in both containers for a real time comparison

[User_Defined]

OK, don't paint the strip with varnish, then might I suggest a strip of aluminium tape covered with a layer of packing tape but use varnish around the edge of the packing tape to seal it from the water, if laid out carefully it should be very accurate.

do this in both containers for a real time comparison

Just tape some foil to the container wall... or laminate some foil or foil tape such that the edges of the metal are covered by the tape. You cant guarantee that the edges will be varnished, any bit of salt water touching that metal will cause a short, and varnishing thin flexible things is just asking for cracks and leaks.

Thin packing tape might work well, no bumps though! Personally I would go with something thicker and more consistent like kapton tape. It is made to be precise and is pretty rugged. Not to mention the polymer material might have a super high dielectric constant.

Oh I forgot to mention you should probably have the wire going inside the saltwater as earth/chasis ground. Also, get that wire to be as close as possible in the salt water to the strip. Aaaaaaand try to have the foil connection be as close as possible to the 555 chip to minimize stray capacitance to other objects.





-UD