CN103645374A

CN103645374A - Non-contact electricity measurement device

Info

Publication number: CN103645374A
Application number: CN201310739151.4A
Authority: CN
Inventors: 周芸
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-12-28
Filing date: 2013-12-28
Publication date: 2014-03-19

Abstract

The invention relates to a non-contact electricity measurement device which is characterized by comprising a 3V direct current power supply, an induction signal pickup and amplification circuit, a complementary type positive feedback oscillating circuit and a loudspeaker YS, wherein the induction signal pickup and amplification circuit consists of a metal induction chip TX, a junction type field effect transistor VT1 and a resistor R1; the complementary type positive feedback oscillating circuit consists of a resistor R2, an NPN type transistor VT2, a resistor R3, a PNP type transistor VT3, a capacitor C1, a resistor R4 and the loudspeaker YS. In order to overcome the defect that hazard-free induced electromotive force cannot be identified by a conventional test pencil, the invention provides the electricity measurement device which can identify dangerous electric shock voltage and also can identify hazard-free induced electromotive force or static electricity. The device can notify whether detected electric wires, electrical equipment and other electric devices are electrified through an acoustical signal under the condition of not contacting an electrified body, and the device is a practical testing tool for electricians and electronic technicists.

Description

Contactless survey electric installation

Technical field

The invention belongs to electronic technology and survey electrical domain, is about a kind of contactless survey electric installation.

Background technology

At present, on market, the structure of known test pencil is to be composed in series by examination electrical contact, current-limiting resistance, neon tube, metal spring and hand touched electrode.Test contact and tested live metal object contact, staff contact hand touched electrode forms loop, and when tested metal object has higher voltage relative to the earth, neon tube starter, represents that tested metal object is charged.But, there are in actual use the metal shell of a lot of consumers or hardware without to the adventurous electric shock voltage of human body, only the distributed capacitance induction by consumer metal part produces electromotive force (voltage), general test pencil can not be identified lower than the induction electromotive force below 80V, whether this leaks electricity to detection consumer and brings certain limitation, is easy to cause misjudgment.

In order to overcome existing test pencil on market, can not identify the deficiency without dangerous induction electromotive force, develop and a kind ofly can either identify adventurous electric shock voltage, the survey electric installation that also can identify non-hazardous induction electromotive force or static is particularly necessary.

Contactless survey electric installation can be the in the situation that of not contact electrification body, by voice signal, inform whether be detected electric wire, electrical equipment and other electric devices etc. charged, have the advantages such as test is rapid, use is safe, reliable, it is electrician, electronic technology personnel's a kind of practical testing tool.The cost of manufacture of contactless survey electric installation only needs several units, is well suited for factory and develops in batches.

Below describe contactless survey electric installation of the present invention related relevant technologies content in implementation process in detail.

Summary of the invention

Goal of the invention and beneficial effect: in order to overcome existing test pencil on market, can not identify the deficiency without dangerous induction electromotive force, develop and a kind ofly can either identify adventurous electric shock voltage, the survey electric installation that also can identify non-hazardous induction electromotive force or static is particularly necessary.Contactless survey electric installation can be the in the situation that of not contact electrification body, by voice signal, inform whether be detected electric wire, electrical equipment and other electric devices etc. charged, have the advantages such as test is rapid, use is safe, reliable, it is electrician, electronic technology personnel's a kind of practical testing tool.The cost of manufacture of contactless survey electric installation only needs several units, is well suited for factory and develops in batches.

Circuit working principle: it is comprised of sensor circuit and sound generating circuit two large divisions, wherein: junction field effect transistor VT1, utilizes its high input impedance and voltage amplification characteristic as induced signal, pick up and amplify.

NPN transistor VT2, PNP transistor VT3 are two opposite polarity transistors, the emitter junction of PNP transistor VT3 is the load of NPN transistor VT2, and NPN transistor VT2 provides base current for PNP transistor VT3, their work of working in coordination forms complementary type positive feedback oscillatory circuit under the positive feedback effect of capacitor C 1, resistance R 4.

When 3V direct supply is connected, if survey electric installation, not yet sense electrified body, because junction field effect transistor VT1 is in zero inclined to one side state, drain D and the resistance between source S of junction field effect transistor VT1 are less, the NPN transistor VT2 base stage being connected with drain D is in low level, NPN transistor VT2 because of without suitable bias current in cut-off state, the complementary type positive feedback oscillatory circuit being comprised of NPN transistor VT2 and PNP transistor VT3 etc. is not worked, and loudspeaker YS can sounding.Once survey electric installation, approach electrified body, the metal sensing chip TX being connected with junction field effect transistor VT1 grid G will sense faint electric field signal, resistance value between junction field effect transistor VT1 drain D, source S is increased, its dividing potential drop rises with respect to resistance R 1 thereupon, NPN transistor VT2 obtains suitable bias current and conducting, the complementary type positive feedback oscillatory circuit being comprised of NPN transistor VT2 and PNP transistor VT3 etc. is worked immediately, oscillating current, by loudspeaker YS, makes it to send " beep ... " sound.

The frequency of operation of complementary type positive feedback oscillatory circuit depends primarily on time constant T, and T=R2 * C1, therefore increase and decrease resistance R 2 resistances or capacitor C 1 capacity can change the tone of loudspeaker YS sounding.

Technical scheme: contactless survey electric installation, it comprises that 3V direct supply, induced signal pick up and amplifying circuit, complementary type positive feedback oscillatory circuit and loudspeaker YS, it is characterized in that:

Induced signal picks up and amplifying circuit: it is comprised of metal sensing chip TX, junction field effect transistor VT1 and resistance R 1, the grid G of junction field effect transistor VT1 meets metal sensing chip TX, the drain D of junction field effect transistor VT1 is by resistance R 1 connection circuit positive pole VCC, the source S connection circuit ground GND of junction field effect transistor VT1;

Complementary type positive feedback oscillatory circuit: it is by resistance R 2, NPN transistor VT2, resistance R 3, PNP transistor VT3, capacitor C 1 and resistance R 4 and loudspeaker YS form, one end of base stage connecting resistance R2 of NPN transistor VT2 and one end of capacitor C 1, the other end of resistance R 2 connects the drain D of junction field effect transistor VT1, the other end of capacitor C 1 connects the collector of PNP transistor VT3 by resistance R 4, the collector of NPN transistor VT2 connects one end of base stage and the resistance R 3 of PNP transistor VT3, the anodal VCC of other end connection circuit of resistance R 3, the emitter connection circuit ground GND of NPN transistor VT2, the anodal VCC of emitter connection circuit of PNP transistor VT3, the collector of PNP transistor VT3 is by loudspeaker YS connection circuit ground GND,

3V DC power anode is connected with circuit anode VCC, and 3V DC power cathode is connected with circuit ground GND.

Accompanying drawing explanation

Accompanying drawing is embodiment circuit working schematic diagram of contactless survey electric installation provided by the invention.

Embodiment

According to contactless survey electric installation circuit working schematic diagram shown in the drawings and accompanying drawing explanation, and according to annexation between components and parts in the each several part circuit described in summary of the invention, and the components and parts technical parameter described in embodiment requires and circuit production main points are implemented to realize the present invention, below in conjunction with embodiment, correlation technique of the present invention is further described.

The selection of components and parts and technical parameter thereof

Element number	Components and parts title	Model or technical indicator	Quantity	Remarks
					VT1	Junction field effect transistor	3DJ6 or 3DJ7	1	IDSS＜1mA
VT2	NPN transistor	2SC9013、β≥180	1	?
					VT3	PNP transistor	2SC9015、β≥160	1	?
R1	Metalfilmresistor	1/8W、4.7KΩ	1	Be used for regulating sensitivity
					R2	Metalfilmresistor	1/8W、47KΩ	1	?
R3	Metalfilmresistor	1/8W、6.8KΩ	1	?
					R4	Metalfilmresistor	1/8W、1.5KΩ	1	Positive feedback
C1	Electric capacity	0.047μF/40V	1	Positive feedback
					YS	D.sp.	8Ω、0.25W	1	?
DC	Direct supply	No. 5 dry cells	Two joints	?

Circuit production main points, circuit debugging and using method

Because of the circuit structure of contactless survey electric installation fairly simple, as long as the electronic devices and components performance of generally selecting is intact, and the components and parts annexation in accompanying drawing is welded to specifications, physical connection line and welding quality are after careful inspection is correct, and circuit of the present invention does not substantially need to carry out any debugging and can normally work;

Metal sensing chip TX makes of the copper sheet of size 20mm * 15mm, and requires the surface coverage one deck insulating material at metal sensing chip TX, to guarantee directly not touch charged object when surveying electricity;

Need to remind: because drain D and the source S of junction field effect transistor VT1 is symmetrical, so bipod can exchange use when actual welding;

Circuit debugging: in the environment away from electrified body, resistance R 1 can replace with 1 trimmer potentiometer, makes loudspeaker YS in critical sounding state, makes it obtain the best current sensitivity of surveying; The effective detection range of contactless survey electric installation is relevant with the resistance size of metal sensing chip size and resistance R 1.

If loudspeaker YS tone of sound is too overcast or point too, can be by suitably reducing or increasing resistance R 2 resistances or capacitor C 1 capacity is regulated;

If the volume of sensation loudspeaker YS is inadequate, can suitably increase the resistance of resistance R 4; But the resistance of resistance R 4 can not be too large, otherwise power consumption during circuit working can obviously increase, and makes circuit starting of oscillation difficulty;

The index that contactless survey electric installation is debugged: for the detection range >=0.5cm that surveys 36～100V AC and DC electrified body; For the detection range >=4cm that surveys alternating current 220V electrified body; 10KV ultra-high-tension power transmission line detection range >=60cm;

Due to detection range and the electrified body voltage height relation in direct ratio of induction type electricity measurer, so user, after obtaining certain empirical data, can estimate according to detection range the height of tested voltage.

Claims

1. a contactless survey electric installation, it comprises that 3V direct supply, induced signal pick up and amplifying circuit, complementary type positive feedback oscillatory circuit and loudspeaker YS, it is characterized in that:

Described induced signal picks up and amplifying circuit is comprised of metal sensing chip TX, junction field effect transistor VT1 and resistance R 1, the grid G of junction field effect transistor VT1 meets metal sensing chip TX, the drain D of junction field effect transistor VT1 is by resistance R 1 connection circuit positive pole VCC, the source S connection circuit ground GND of junction field effect transistor VT1;

Described complementary type positive feedback oscillatory circuit is by resistance R 2, NPN transistor VT2, resistance R 3, PNP transistor VT3, capacitor C 1 and resistance R 4 and loudspeaker YS form, one end of base stage connecting resistance R2 of NPN transistor VT2 and one end of capacitor C 1, the other end of resistance R 2 connects the drain D of junction field effect transistor VT1, the other end of capacitor C 1 connects the collector of PNP transistor VT3 by resistance R 4, the collector of NPN transistor VT2 connects one end of base stage and the resistance R 3 of PNP transistor VT3, the anodal VCC of other end connection circuit of resistance R 3, the emitter connection circuit ground GND of NPN transistor VT2, the anodal VCC of emitter connection circuit of PNP transistor VT3, the collector of PNP transistor VT3 is by loudspeaker YS connection circuit ground GND,

Described 3V DC power anode is connected with circuit anode VCC, and 3V DC power cathode is connected with circuit ground GND.