Passive magnetic field detector

• US 10,725,192 B2
• Filed: 10/10/2018
• Issued: 07/28/2020
• Est. Priority Date: 10/10/2018
• Status: Active Grant

• Current Assignee: The Government Of The United States As Represented By The Secretary Of The Navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Camp, James Thomas
• Primary Examiner(s): Astacio-Oquendo, Giovanni
• Application Number:
  US16/155,934
• Publication Number:
  US 20200116888A1
• Time in Patent Office: 657 Days
• Field of Search: 324260, 324200, 324 7611
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence
• CPC Class Codes: G01R 33/028 Electrodynamic magnetometers
• CPC Class Codes: G01V 3/10 using induction coils
• CPC Class Codes: G08B 21/02 Alarms for ensuring the safety of persons
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold
• CPC Class Codes: G08B 3/10 using electric transmission; using electromagnetic transmission
• CPC Class Codes: G08B 5/36 using visible light sources

Abstract

A passive magnetic flux detector (PMFD) is provided for indicating an ambient magnetic field. The PMFD includes a coil, a rectifier, and an indicator. The indicator is either a light emitting diode (LED), a piezoelectric speaker or both.

Claims

1. A passive magnetic flux detector (PMFD) for indicating an ambient magnetic field, said PMFD comprising:

an inductor that receives an induced voltage caused by the magnetic field;

a rectifying circuit, comprising a diode and a capacitor, that rectifies said induced voltage from said inductor as a rectified voltage, said diode having a diode potential; and

an alarm indicator that signals in response to said rectified voltage of said rectifying circuit exceeding said diode potential.

2. The PMFD according to claim 1, wherein said ala indicator is a light emitting diode (LED).

3. The PMFD according to claim 1, wherein said alarm indicator is an acoustic speaker.

4. The PMFD according to claim 1, wherein said alarm indicator is a light emitting diode (LED) and an acoustic speaker.

5. The PMFD according to claim 1, wherein said diode has depletion capacitance for rectifying the magnetic field at high frequency.

6. The PMFD according to claim 1, wherein said capacitor has a cape lance of 100 nF.