I found a site with a photo of the type of coil that i made
http://www.adermark.com/dowsing_rods...categoryid=197 although i did not put a weight on the end or a wooden handle.
And yes this knowledge has been around for a very very long time. There is a rock painting 20,000-30,000 years old in Western Australia showing this.
You can detect extremly long distances using this method.
I think my idea combined with geo's 555 circuit may be a basic start for this type of detection. This will allow some experimentation by members to calculate the distance to the target object. The second stage would be to add a discriminator to the circuit, but to do this i think we need to know more about the triboelectric effect of static electricity.
regards to all