Generally speaking, a quicker sweep will find more substantial, further gold targets, but will usually skip compact shallow gold. A slower sweep will usually lose sensitivity on the deepest targets, but will see modest shallow gold simpler. The 2 principal coils are linked to an oscillator that generates a radio https://whenyouriseup.activeboard.com/t72455561/when-a-gold-detector-finds-more-than-gold/?page=1#lastPostAnchor