JP2001264449A - Detector for metal buried in snow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for metal, particularly for metal buried in snow, capable of detection by detecting a change in an oscillating frequency caused by a change in permeability of a coil. SOLUTION: In this detector for metal, the coil is wound around a bar dust core 1 to make the coil oscillate, and a phenomenon where the oscillating frequency is changed by the change in the permeability of the coil when the metal approaches the dust core is used. The locator can detect the metal buried in snow up to 20 cm in depth when the metal is as much as a manhole cover.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The field of electromagnetism, radio wave engineering

[0002]

[Prior Art] Unknown

[0003]

When searching for a metal such as a manhole cover buried in snow in winter, it may be difficult to use only an index indicating a point on the drawing.

[0004]

Means for Solving the Problems The present invention has been devised in order to cope with the above-mentioned case.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wire loop is wound around a rod-shaped dust core,
A metal detector that utilizes the phenomenon that the oscillation frequency changes due to the change in the magnetic permeability of the wire when the metal approaches the dust core, oscillated by the wire.

[0006]

(Refer to the drawings) In the electric circuit shown in the drawing (a), the wire loop L1 wound around one dust core
, A transistor TR1, a resonance capacitor C1,
A wave oscillation circuit is formed by the feedback capacitor C2. The oscillation frequency band of the oscillation circuit shown in FIG.
It is a long wave band around Hz. This oscillation frequency is
It changes by bringing the metal closer to the dust core. This signal is amplified by the transistor TR2 and L3,
Tune to the resonance circuit by C3. Further, this signal is amplified by TR3, multiplied to the frequency range that can be received by the radio receiver, and tuned to the resonance circuit by L4 and C4. The signal is received by directly connecting to the antenna of the radio receiver shown in drawing (c), and the presence of the metal is detected as a change in sound by moving the dust core wire up and down on the metal. The power supply used a commercially available stabilized power supply kit. In my case, it was received by AM radio, but it is also possible to read the change in magnetic permeability as a numerical value by shaping the waveform through a limiter, FM detection and DC amplification. Also, with the development of highly directional sensors, the possibility of projecting the world of magnetic field lines onto a CRT can be considered.

[0007]

[Embodiment] The drawing shows the electric circuit of a metal detector buried under the snow that I devised.

[0008]

[Effect of the Invention] If the metal is the same size as a manhole cover, it can be detected up to a burial depth of about 20 cm in snow.

[Brief description of the drawings]

DESCRIPTION OF SYMBOLS 1 Dust core 2 3-core shielded wire 3 Battery 4 Stabilized power supply (kit made by SK Electronics) 5 Radio receiver (Matsushita Electric Model RF-U)
36) 6 antenna 7 TR1 to TR3; transistor 8 C1 to C4; capacitor 9 L1 to L4; coil

[Procedure amendment]

[Submission date] December 4, 2000 (200.12.
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

Fig. 1 Electric circuit of a metal detector buried in snow

Fig. 2 Schematic diagram of a metal detector buried in snow

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

Claims (2)

[Claims] 1. Metal detection by detecting a change in oscillation frequency due to a change in the magnetic permeability of a coil. 2. Detection of metal buried in snow