Balancing circuit for a metal detector
AssigneeCarnes Company, Inc.
InventorJoseph S. Simon
Life of this patent
Estimating the term…
Abstract
A balancing circuit for a metal detector. The metal detector includes an oscillating power source, a transmit coil connected to the oscillating power source, first and second receive coils inductively coupled to the transmit coil, a first amplitude balancing circuit connected to the first receive coil, and a first phase balancing circuit connected to the first receive coil. The first phase balancing circuit includes a capacitor and a variable resistor.
Claims22
A metal detector, comprising:
- an oscillating power source;
- a transmit coil connected to the oscillating power source;
- first and second receive coils inductively coupled to the transmit coil;
- a first amplitude balancing circuit connected to one of the first receive coil and the second receive coil;
- and
- a first phase balancing circuit connected to one of the first receive coil and the second receive coil, the first phase balancing circuit including a first capacitor and a first variable resistor.
A method of balancing a metal detector having a transmit coil, first and second receive coils inductively coupled to the transmit coil, a differential circuit coupled to the first and second receive coils, a first amplitude balancing circuit coupled to one of the first receive coil and the second receive coil and including a first variable resistor, and a first phase balancing circuit coupled to one of the first receive coil and the second receive coil and including a capacitor and a second variable resistor, the method comprising:
- detecting a difference between a signal from the first receive coil and a signal from the second receive coil when there is no material in the metal detector;
- adjusting the first variable resistor to reduce the difference;
- adjusting the second variable resistor to reduce the difference;
- and
- repeating adjustment of the first and second variable resistors to reduce the difference.
A signal adjuster for an inductor, comprising:
- an amplitude adjuster configured to provide a resistance between a lead of the inductor and ground;
- and
- a phase adjuster configured to provide a capacitance and a variable resistance between a lead of the inductor and ground, the variable resistance configured to adjust a phase of a signal generated by the inductor.
Dependencies are inferred from the claim text.