CN102508304B

CN102508304B - Hand-held metal detector

Info

Publication number: CN102508304B
Application number: CN 201110374726
Authority: CN
Inventors: 韩春龙
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-11-23
Filing date: 2011-11-23
Publication date: 2013-05-01
Anticipated expiration: 2031-11-23
Also published as: CN102508304A

Abstract

The invention relates to a hand-held metal detector. The hand-held metal detector consists of a 3V direct current power supply, a detection probe, a three-point capacitive resonance circuit, a resistance-capacitance amplification circuit, a voltage-doubling detection and filter circuit and a direct current amplification and detection indicating circuit. The hand-held metal detector can solve the problem of relatively simple metal detection in daily life, overcome defects and shortcomings of large metal detection instruments, solve the problem of detection of metal objects which are buried in a relatively shallow position in the daily life, such as metal pipes buried in a wall, and overcome common defects and shortcomings of complicated operation and high price of large metal detection instruments; and the hand-held metal detector is relatively simple in circuit and relatively low in manufacturing cost, so that the hand-held metal detector is quite suitable to be developed in batch as a common tool.

Description

Handheld metal detector

Technical field

The invention belongs to electronic technology, security technical field, relate to a kind of Handheld metal detector.

Background technology

The instrument kind that is used for specially surveying metal object is more, powerful large-scale metal detection equipment can be used for detecting 2m whether to keep the metals such as gun, dagger in interior human body, luggage, the parcel, and this class detection instrument is applicable to the public arenas such as airport, station, harbour, customs, public security, frontier defense luggage and articles or human body are fast and safely checked; Also be useful on survey hidden in wall electric wire, be embedded in underground water pipe or cable, even can be used in underground hunt for treasure or survey be imbedded in the underground metal that deeply reaches 5m.Their common feature is that detection range is far away, and result of detection is accurate.These metal detection equipment results of use are good, but the ubiquity price high, the problem such as be difficult to popularize.For solving the detection problem of relatively simple metal object, Handheld metal detector of the present invention can remedy defective and the deficiency of the existence of large-scale metal detection equipment.

Summary of the invention

Goal of the invention and beneficial effect: Handheld metal detector of the present invention, can solve the daily relatively simple metal detection problem that runs into, can remedy the shortcomings and deficiencies that large-scale metal detection equipment exists.The present invention can solve daily run into bury relatively shallow metal object detection problem, as: survey the metal pipe line of dark row in wall etc., remedy large-scale metal detection equipment ubiquity complicated operation, defective and the deficiency such as expensive.Fairly simple because of the circuit of Handheld metal detector, cost of manufacture is lower, be well suited for carrying out batch exploitation as a kind of common tool.

The circuit working principle: the major part of Handheld metal detector is an oscillatory circuit that is in critical conditions, when having metal object to approach detection probe (telefault L), survey the electromagnetic field that produces in the probe and will induce eddy current at tested metal object, the eddy current energy source is equivalent to increase in the circuit loss in the loss of oscillatory circuit itself.If when having metal object and detection probe very near, the loss in the circuit will further strengthen, the Q value of surveying probe reduces, and quit work so that be in the oscillatory circuit of threshold oscillation state, and then red light emitting diodes LED extinguishes in the control circuit.

Silicon triode BG1 and telefault L, capacitor C 1, C2 have consisted of a bikini oscillatory circuit in circuit.When the base stage of silicon triode BG1 in the oscillatory circuit has a positive signal, because the acting in opposition of triode makes the collector signal of silicon triode BG1 for negative.The signal polarity at the two ends of capacitor C 1, C2 all is upper just lower negative, signal is by the feedback of capacitor C 3, signal on the silicon triode BG1 base stage and original signal same-phase, because be positive feedback, so circuit can produce vibration, behind access potentiometer RP, will weaken the intensity of the positive feedback signal in the circuit, be used for the critical conditions of just starting of oscillation of regulating circuit.

The about 40KHz of the oscillation frequency of metal detector, oscillation frequency is mainly determined by telefault L, capacitor C 1, C2.Regulator potentiometer RP can control the size of feedback signal, and control circuit is in firm starting of oscillation state.Resistance R 1 is the biasing resistor of silicon triode BG1.Faint oscillator signal is delivered to silicon triode BG2 by coupling capacitance C4 and is carried out voltage amplification.Because of the signal amplitude after amplifying still smaller, so select two detector diode D1, D2 and two capacitor C 5, C6 to form two multiplication of voltage detecting circuits, DC voltage behind the detection filter makes silicon triode BG3 conducting, at this moment the collector of silicon triode BG3 is in low level, makes red light emitting diodes LED get electric lighting.

As the telefault L of metal detector during near metal object, be in the oscillatory circuit failure of oscillation immediately of vibration critical conditions, signal by coupling capacitance C4 will disappear, the base stage of silicon triode BG3 can not get forward voltage, and make silicon triode BG3 cut-off, red light emitting diodes LED is extinguished by lighting to become.

Technical scheme: Handheld metal detector, formed by 3V direct supply, detection probe and bikini electric capacity oscillatory circuit, rc-coupled amplification circuit, two multiplication of voltage detection filter circuits, direct current amplification and detection indicating circuit, it is characterized in that:

Survey probe and bikini electric capacity oscillatory circuit: by telefault L, oscillating capacitance C1, C2, capacitor C 3, silicon triode BG1 and biasing resistor R1, oscillator signal decay potentiometer RP and resistance R 2 form, two capacitor C 1, be connected on the end of potentiometer RP after the C2 serial connection, two capacitor C 1, the other end of C2 connects respectively the two ends of telefault L, one end of the upper termination capacitor C 3 of telefault L, the base stage of the other end of capacitor C 3 and silicon triode BG1, one end of resistance R 1 links to each other, the collector of the other end of resistance R 1 and silicon triode BG1 meets the anodal VCC of 3V direct supply, the emitter of silicon triode BG1 connects the other end of potentiometer RP and an end of lever arm and resistance R 2 thereof, the lower termination circuit ground GND of the other end of resistance R 2 and telefault L;

Rc-coupled amplification circuit: formed by coupling capacitance C4, silicon triode BG2, biasing resistor R3 and pull-up resistor R4, the emitter of the termination silicon triode BG1 of coupling capacitance C4, the base stage of another termination silicon triode BG2 of coupling capacitance C4 and the end of biasing resistor R3, the anodal VCC of another termination 3V direct supply of biasing resistor R3, the collector of silicon triode BG2 connects the end of pull-up resistor R4, the anodal VCC of another termination 3V direct supply of pull-up resistor R4, the emitter connection circuit ground GND of silicon triode BG2;

Two multiplication of voltage detection filter circuits: formed by coupling capacitance C5, detector diode D1, D2 and filter capacitor C6, the collector of silicon triode BG2 connects an end of capacitor C 5, the negative pole of another termination detector diode D1 of capacitor C 5 and the positive pole of detector diode D2, the negative pole of detector diode D2 connects the base stage of positive pole and the silicon triode BG3 of electrochemical capacitor C6, the negative pole connection circuit ground GND of the positive pole of detector diode D1 and electrochemical capacitor C6;

Direct current amplifies and surveys indicating circuit: be comprised of silicon triode BG3 and red light emitting diodes LED and dropping resistor R5, the base stage of silicon triode BG3 connects the negative pole of detector diode D2, the emitter connection circuit ground GND of silicon triode BG3, the collector of silicon triode BG3 connects red light emitting diodes LED negative pole, the end of the anodal connecting resistance R5 of red light emitting diodes LED, the anodal VCC of another termination 3V direct supply of resistance R 5.

Description of drawings

Accompanying drawing 1 is the circuit working schematic diagram of Handheld metal detector.

Accompanying drawing 2 is detection probe magnetic core and coil baffle plate synoptic diagram of making Handheld metal detector.

Embodiment

The below is accompanying drawing 1 and description of drawings to specifications, with the following Examples relative production technology of the present invention is further described and illustrates.

The selection of components and parts and making

1. be the sensitivity of raising electric circuit inspection and the stability of circuit working, the enlargement factor of silicon triode pipe BG1 should not be too large, and the β value preferably is controlled at 70～90;

2. capacitor C 1, the C2 in the bikini oscillator circuit requires preferably ceramic disc capacitor or select leaded multilayer ceramic capacitor of selection work stability, requires the capacity parameter of two capacitor C 1, C2 to equate;

3. the probe of the detection in the Handheld metal detector (telefault L) is a key element, and it is the telefault with the intermediate frequency magnetic core.￠ 10mm magnetic core is selected the antenna bar magnet in the transistor radio, intercept long 15mm, baffle plate with thick 2 the ￠ 20mm of bakelite paperboard of insulcrete or 1.5mm, respectively dig the concentric circle holes of a ￠ 10mm in the middle of the baffle plate, then be nested in the two ends of ￠ 10mm magnetic core with glue, the telefault magnetic core skeleton of making is seen shown in the Figure of description 2.Enameled wire with ￠ 0.29mm is flat around 300 circles at magnetic core skeleton higher slice, uses at last the resin glue sealing;

4. components and parts title and technical parameter

Component symbol	The components and parts title	Technical parameter	Quantity	Remarks
					BG1	Plastic packaging NPN type triode	2CS9014、β70～90	1
BG2、BG3	Plastic packaging NPN type triode	2CS9014、β≥180	2
					D1、D2	Detector diode	Glassivation 1N60	2
LED	Highlighted red light emitting diodes	￠5、LED	1	Survey indication
					L	Telefault	Φ	10 intermediate frequency magnetic cores, 300 circles	1	Or select finished product
RP	Potentiometer	5.1KΩ	1
					R1	Resistance	1/8W、680KΩ	1	Biasing resistor
R2	Resistance	1/8W、3.3KΩ	2	Negative feedback resistor
					R3	Resistance	1/8W、2MΩ	1	Biasing resistor
R4	Resistance	1/8W、6.8KΩ	1	Pull-up resistor
					R5	Resistance	1/8W、82Ω	1	Dropping resistor
C1、C2、C3	Electric capacity	Ceramic disc capacitor, 0.01 μ F	3	Oscillating capacitance
					C4、C5	Electric capacity	Electric capacity of the dacron, 0.22 μ F	2	Coupling capacitance
C6	Electrochemical capacitor	2.2 μ F/10V filter capacitor	1	Capacity is unsuitable large

Circuit production

Accompanying drawing 1 circuit working schematic diagram to specifications, carefully welding correctness and the welding quality of all components and parts in the check circuit are confirmed that this device welds can enter circuit debugging after errorless.

Circuit debugging

After connecting the 3V direct supply, the descending slow adjustment of the resistance of potentiometer RP is until red light emitting diodes LED lights.Then approach any one end face of surveying probe (telefault L) magnetic core with a metal object, at this moment red light emitting diodes LED will extinguish;

Adjust the sensitivity that potentiometer RP can change metal detector, the equal cisco unity malfunction of the excessive or too small circuit of the resistance of potentiometer RP.If the resistance of potentiometer RP is adjusted correctly, the detection range of surveying probe in the circuit can reach 30mm, and the detection probe on the circuit can detect metal object or the coin of placing under the carpet across carpet;

The detection probe of Handheld metal detector requires away from more than the circuit board element 55mm, and the circuit of metal detector can not use metal shell; The detection probe (telefault L) of metal detecting device can be guided to beyond the metal shell in case of necessity, and be managed to use nonmetallic materials will survey probe and fixed.

Claims

1. a Handheld metal detector is comprised of 3V direct supply, detection probe and bikini electric capacity oscillatory circuit, rc-coupled amplification circuit, two multiplication of voltage detection filter circuits, direct current amplification and detection indicating circuit, it is characterized in that:

Survey probe and bikini electric capacity oscillatory circuit by telefault L, capacitor C 1～C2, capacitor C 3, silicon triode BG1 and resistance R 1, potentiometer RP and resistance R 2 form, after being connected in series, two capacitor C 1～C2 are connected on the end of potentiometer RP, the other end of two capacitor C 1～C2 connects respectively the two ends of telefault L, one end of the upper termination capacitor C 3 of telefault L, the base stage of the other end of capacitor C 3 and silicon triode BG1, one end of resistance R 1 links to each other, the collector of the other end of resistance R 1 and silicon triode BG1 meets the anodal VCC of 3V direct supply, the emitter of silicon triode BG1 connects the other end of potentiometer RP and an end of lever arm and resistance R 2 thereof, the lower termination circuit ground GND of the other end of resistance R 2 and telefault L;

Rc-coupled amplification circuit is comprised of coupling capacitance C4, silicon triode BG2, biasing resistor R3 and pull-up resistor R4, the emitter of the termination silicon triode BG1 of coupling capacitance C4, the base stage of another termination silicon triode BG2 of coupling capacitance C4 and the end of biasing resistor R3, the anodal VCC of another termination 3V direct supply of biasing resistor R3, the collector of silicon triode BG2 connects the end of pull-up resistor R4, the anodal VCC of another termination 3V direct supply of pull-up resistor R4, the emitter connection circuit ground GND of silicon triode BG2;

Two multiplication of voltage detection filter circuits are comprised of coupling capacitance C5, detector diode D1～D2 and filter capacitor C6, the collector of silicon triode BG2 connects an end of capacitor C 5, the negative pole of another termination detector diode D1 of capacitor C 5 and the positive pole of detector diode D2, the negative pole of detector diode D2 connects the base stage of positive pole and the silicon triode BG3 of electrochemical capacitor C6, the negative pole connection circuit ground GND of the positive pole of detector diode D1 and electrochemical capacitor C6;

Direct current amplifies and surveys indicating circuit and is comprised of silicon triode BG3 and red light emitting diodes LED and dropping resistor R5, the base stage of silicon triode BG3 connects the negative pole of detector diode D2, the emitter connection circuit ground GND of silicon triode BG3, the collector of silicon triode BG3 connects red light emitting diodes LED negative pole, the end of the anodal connecting resistance R5 of red light emitting diodes LED, the anodal VCC of another termination 3V direct supply of resistance R 5.