Fixed pulse delay vs. variable delay

[GeoMax]

What is the advantage to have a variable pulse delay functionality in a PI circuit? We assume that a fast PI coil, that can handle a minimum sample pulse delay of 10us, is connected to the circuit. If the sampling pulse delay is set to a fixed value of 10us in the circuit, we should be able to detect small gold nuggets as well as bigger iron objects. What is than the advantage to have a variable sample pulse delay functionality of e.g., 10 to 100us in the same circuit? Or is it to “tune out” trash like small iron junk, bottle caps or pull taps?

[Carl-NC]

I always set it to minimum unless hunting in salt water. There it may need to be increased for stability.

[Eddy71]

The point of setting high delay values - so that the fine gold does not interfere with the collection of heavy iron!