Hi colleagues,

I want to build a water descaling device bcus our water here has a
hardness level about 25 German Grades. I have seen such commercial things,
but I do not understand:
there is one which has two output wires should be wound on the pipe.
However, the two wires aren't connected so this can produce only
electrical (no magnetic!) field. Such way - assuming it works - it will be
useless if the pipe is conducting. However, it is not said it may not be.
So I guess it is a hoax. This one has a NE555 and generates 5V, 1kHz.

I have read about another one, it produces magnetic field as there are
four coils on the pipe and it is supplied with a very-low frequency
modulated square wave (it is said the frequency changes between 1 to 12
kHz within 20 seconds). It seems for me more believable. I would do it, of
course with a PIC. Now the question:

does know anybody how much flux must be supplied? I. e. how many windings
the coil(s) must have, and how much current must be supplied. All the
providers say their device consumes practically nothing... Of course, it
would be nice to know from a proven source, whether this all works.

Thank you in advance
Imre