P.I. Tuned Marker Locator

[Eric Foster]

Most PI experimenters have found that if there is an unused coil close to an operating PI, then a ringing waveform will appear on a scope connected to the first amplifier, that cannot be damped out. Even reels of hookup wire under the bench will re-radiate this ringing over quite a considerable distance.

About twenty years ago I wondered if this phenomenon could be put to good use and conducted some experiments which are outlined below. Two possible applications arose as a result of customer enquiries. Sometimes a piece of land needs to be marked out without using above ground stakes, or an object such as a buried pipe to have its course traced. Buried metal markers are sometimes used, and conventional metal detectors used to find them, but there is always the possibility of other metal objects being in the vicinity that can cause confusion. Objects on underwater wreck sites sometimes also need to be marked in a less visible way than using a buoy.

The range at which a tuned circuit could be detected was far in excess of normal metal targets and if the marker could be made small enough then it would be very effective in the above applications. Also, it has the distinct advantage of being completely passive, until excited by the transmitted waveform. The marker

 

[Sunny Jim]

That is a good idea Eric.

The utility people have been at the forefront of having a need for precision locates. It likely has some competition with the RFID products that can give data. No doubt there is a need out there that is perfect for this idea. Perhaps just a new type of proximity device?

A new animal door? Livestock counter? Bathroom pass?
How about a new back-up system for long-haul trucks?
Marina monitor? Embedded locates for construction for voids or future holes in concrete? Survey points?

Good luck and keep working those 'outside the box' ideas.

SJ