Description:
A Beat Balance Metal Detector made from discrete components.
Notes:
Various embodiments of the BB metal detector have been
published, and it has been widely described in the press as
a new genre. Instead of using a search and a reference
oscillator as with BFO, or Tx and Rx coils as with IB, it
uses two transmitters or search oscillators with IB-style
coil overlap. The frequencies of the two oscillators are
then mixed in similar fashion to BFO, to produce an audible
heterodyne. On the surface of it, this design would seem to
represent little more than a twinned BFO metal detector.
However, what makes it different above all else, and
significantly increases its range, is that each coil
modifies the frequency of the adjacent oscillator through
mutual coupling. This introduces the "balance" that is
present in an IB metal detector, and boosts sensitivity well
beyond that of BFO. Since the concept borrows from both BFO
and IB, I have given a nod to each of these by naming it a
Beat Balance Metal Detector, or BB for short. Happy hunting!
