Why does the SDC2300 beat the more expensive Minelab PI detectors?
To explain this we need to know a little about how these detectors work. The coil transmits a magnetic field generated by a pulse of current, or a series of pulses. This magnetic field causes “Eddy Currents” to flow in any metal or mineralised object within reach of that field. When the detector stops the pulse train, we need to wait for the coil voltage to essentially fall to zero before we can use the coil as a receiver (an aerial), to pick up the tiny magnetic fields generated by the flow of eddy currents in any object within range. The electronics process these as a signal and gives us an audio output to alert us that there is a target within range.
The amount of time that the eddy currents flow before dissipating is generally known as the ‘decay time”. We can influence these targets and the decay time by using different sized coils. Small/shallow targets can have their decay time lengthened by switching to a smaller coil which has more turns of wire in it, and therefore will emit a stronger magnetic field, and in turn, the edddy currents generated in the target will be stronger, so the decay time will lengthen. We can cause a similar scenario by changing the detector settings or timings.
The “sample delay” (time needed to let the coil go to zero) needs to be shorter than the decay time, otherwise the target is not detectable. The SDC sample delay is so much faster that conventional PI detectors that it is able to detect nuggets and specimens that conventional PI detectors ignore due to the decay times of those targets. This is the MPF (Multi Period Fast) technology that Minelab have introduced into the SDC2300. Coupled with a “smooth” type of timing and an appropriate motion filter, the SDC can sample extremely quickly, yet still ignore the ground noise normally associated with a fast sample delay on a PI machine.
Due to the above the SDC2300 is capable of detecting nuggets and specimens that other PI detectors will not detect regardless of what settings or coil that detector utilises. These are not always small nuggets as some specimens that hold a considerable amount of gold may be completely ignored by the other PI’s because the gold is very fine and disseminated, whereas the SDC will easily recognise them. Couple that with the ability to basically ignore most ground, hotrocks and interference (EMI) and we have a brilliant little package that is easy to use, powerful, and suits beginners to a tee.