CN208314047U - A kind of point-and-shoot multimeter - Google Patents

Abstract

The utility model discloses a kind of point-and-shoot multimeters, including input port, divide dropping resistor, protect converter, A/D conversion circuit, main power source, LCD display, the electric connection of the input port and partial pressure dropping resistor, the partial pressure dropping resistor output end is connect with protection switch input, the protection converter output end is connect with A/D conversion circuit input terminal, and A/D conversion circuit output end is connect with protection switch input, the partial pressure dropping resistor output end is connect with A/D conversion circuit input terminal, the main power source output end is connect with A/D conversion circuit input terminal, the A/D conversion circuit output end is connect with LCD display input terminal, this point-and-shoot general-purpose watch circuit is reasonable, it is applied widely, it is powerful, according to the requirement of measurement, accomplish that measurement is accurate, surely It is fixed, no matter measure DC voltage, alternating voltage and resistance, electric current all can automatic identification measurement, measured value is shown on LCD.

Description

A kind of point-and-shoot multimeter

Technical field

The utility model relates to multimeter technical field, specially a kind of point-and-shoot multimeter.

Background technique

A kind of digital multimeter, multifunctional electronic measuring instrument, generally comprises the functions such as ampere meter, voltmeter, ohmmeter, Otherwise referred to as multimeter, multi-purpose meter, universal metre or avometer, digital multimeter have for Basic Troubleshooting just Portable device also has the device for being placed on workbench, and some resolution ratio can achieve seven, eight, and digital multimeter (DMM) is exactly The electronic instrument to be used in electric measurement, it can have many specific functions, but major function be exactly to voltage, resistance and Electric current measures, digital multimeter, as the multifunctional electronic measuring instrument of modernization, is mainly used for physics, electrical, electronics Etc. fields of measurement, existing patent CN205506898U a kind of digital multimeter is provided, repacking has lithium ion battery, electricity storage Greatly, overlength works, but the measurement measurement of this multimeter is unstable, and measurement accuracy is low, and does not have automatic identification and measure function, is This, it is proposed that a kind of point-and-shoot multimeter.

Summary of the invention

The purpose of this utility model is to provide a kind of point-and-shoot multimeters, to solve mentioned above in the background art ask Topic.

To achieve the above object, the utility model provides the following technical solutions: a kind of point-and-shoot multimeter, including input terminal Mouth, partial pressure dropping resistor, protection converter, A/D conversion circuit, main power source, LCD display, the input port and differential pressure drop The electric connection of piezoresistance, the partial pressure dropping resistor output end are connect with protection switch input, the protection converter Output end is connect with A/D conversion circuit input terminal, and A/D conversion circuit output end is connect with protection switch input, described Partial pressure dropping resistor output end is connect with A/D conversion circuit input terminal, the main power source output end and A/D conversion circuit input terminal Connection, the A/D conversion circuit output end are connect with LCD display input terminal.

Preferably, the A/D conversion circuit is electrically connected with backup power source.

Preferably, the A/D conversion circuit is electrically connected with pcb board.

Compared with prior art, the utility model has the beneficial effects that this point-and-shoot multimeter is by A/D conversion circuit, aobvious Show the high-power partial pressure dropping resistor of device, power supply, high resistant, input protection converter composition, it can be into resistance measurement, voltage measurement, electricity Flow measurement, this point-and-shoot general-purpose watch circuit is reasonable, applied widely, powerful, according to the requirement of measurement, accomplishes that measurement is quasi- Really, stablize, no matter measure DC voltage, alternating voltage and resistance, electric current all can automatic identification measurement, by measured value on LCD It shows.

Detailed description of the invention

Fig. 1 is the utility model total system figure structure schematic representation；

Fig. 2 is the utility model circuit output control figure schematic diagram.

In figure: 1, input port；2, dropping resistor is divided；3, converter is protected；4, A/D conversion circuit；5, main power source；6, LCD display.

Specific embodiment

The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without making creative work Every other embodiment obtained, fall within the protection scope of the utility model.

The utility model provides a kind of technical solution referring to FIG. 1-2: a kind of point-and-shoot multimeter, including input port 1, divide dropping resistor 2, protection converter 3, A/D conversion circuit 4, main power source 5, LCD display 6, the input port 1 with point The electric connection of pressure drop piezoresistance 2,2 output end of partial pressure dropping resistor are connect with protection 3 input terminal of converter, the protection 3 output end of converter is connect with 4 input terminal of A/D conversion circuit, and 4 output end of A/D conversion circuit and protection 3 input terminal of converter Connection, 2 output end of partial pressure dropping resistor are connect with 4 input terminal of A/D conversion circuit, and 5 output end of main power source and A/D turn The connection of 4 input terminal of circuit is changed, 4 output end of A/D conversion circuit is connect with 6 input terminal of LCD display.

The A/D conversion circuit 4 is electrically connected with backup power source, increases device charge capacity, lengthens working hours, avoid work Make unexpected terminal, device is caused to destroy.

The A/D conversion circuit 4 is electrically connected with pcb board, and pcb board has overload-resistant function, prevents device circuit board mistake It carries, prolongs the service life.

Working principle are as follows: resistance measurement state: input terminal VR is respectively by 50k*4(R16+R17+R18+R20), 900k (R15), three accesses of 10M (R10+R11) composition, static and not under input state, by the A1 foot output DC0.6v scanning of A/D Voltage (voltage can be set to DC 0.6V-1V and be ok, and principle is the same, described below by taking DC0.6V as an example), passes through respectively R15 (900K) and 50*4 (R16, R17, R18, R20) is input to 11 feet and 4 feet of SGM85742, A/DP20 foot output at this time High level makes the Y and Y3 of SGM85742, and X and X3 are connected, and A/D foot A5 input voltage is just substantially equal to the output voltage of A1 DC0.6V, the voltage is less than or equal to D0.6V at this time, and A/D determines the state for resistance mode, if there is resistance at the end VR and the end GND Access, the DC0.6V at the end A5 will change, and A/D is it is determined that will enter resistance measurement state at this time, and at this moment, A1 is just not In output DC0.6V scanning voltage, but resistance measurement voltage DC0.6V is provided by A2, since the A/D connection respectively switched is connected, According to the principle of resistance ratio mensuration, the measurement of resistance automatic range is realized, i.e., adjustable resistance starts to measure, because in the access The resistance of 50k*4 is (resistance plays the role of decompression) bigger than normal, then by low tension switch SGM85472 Lai open or closed and A/D chip Communication, so the resistance measurement of the circuit is if it is 2000, resistance measurement is just 2K/20K/200K/2M/20M, if it is 4000, resistance measurement 4k/40k/400K/4M/40M, 6000,8000,10000 etc. can also be changed to,

Voltage measurement: input terminal VR is respectively by 50k*4(R16+R17+R18+R20), 900k (R15), 10M (R10+R11) Three accesses composition, when having voltage input, and when the A1 foot greater than A/D exports DC0.6v scanning voltage, the A5 foot of A/D receives To the voltage for being greater than 0.6V, for A1 just not in the scanning voltage of output DC0.6V, A/D enters voltage measuring mode at this time, this When P20 export low level, the Y and Y3 of SGM85472, X and X3 are disconnected, and voltage would not flow to the A5 and A2 of A/D, only from A1 Input, into voltage measurement, even if input high pressure DC1000V or AC750V, by high resistant (R15=900K and R16+R17+R18+ R20=200k) decompression after, the voltage for flowing to SGM85472 is also very low, play the role of safety pressure protection, if inputted simultaneously AC and DC voltage, A/D with amplitude it is high do the standard determined, if the same amplitude, alternating voltage is preferential, in this way the circuit Can automatic identification DC voltage, the effect of alternating voltage, resistance, if measurement voltage be lower than DC scanning voltage, A/D again it is extensive Resistance measurement state is arrived again.

Current measurement: passing through coil-induced electric current, after resistance R6, R7, R9 partial pressure, is input to the end A3 of A/D, if There is signal input at the end A3 and A1, just measures by override of A3, shows on LCD after being calculated by A/D.

Color screen backlight control part: 14 feet of A/D are high frequency output foot, the frequency of about 10K or so, by diode multistage Voltage is raised to DC5V or so after multiplication of voltage, by A/D P23 and P24 control multimeter backlight and flashlight function, in the past I In the circuit of normal power supply DC1.5V*2 be all directly to carry out backlight and flashlight with the battery to power, when battery is in DC2.4v When, backlight is just very dim, still keeps super brightness using backlight when thoroughly solving battery low pressure after the circuit, is surveying During amount, if A/D is in measuring state, P24 just controls backlight unlatching, if not controlling foot P24 in measuring state and giving Certain delay time is given, low level is just exported and turns off backlight, just really accomplished economize on electricity after the circuits improvement, energy conservation, extended electricity The service life in pond.

It should be noted that, in this document, relational terms such as first and second and the like are used merely to a reality Body or operation are distinguished with another entity or operation, are deposited without necessarily requiring or implying between these entities or operation In any actual relationship or order or sequence.Moreover, the terms "include", "comprise" or its any other variant are intended to Non-exclusive inclusion, so that the process, method, article or equipment including a series of elements is not only wanted including those Element, but also including other elements that are not explicitly listed, or further include for this process, method, article or equipment Intrinsic element.

While there has been shown and described that the embodiments of the present invention, for the ordinary skill in the art, It is understood that these embodiments can be carried out with a variety of variations in the case where not departing from the principles of the present invention and spirit, repaired Change, replacement and variant, the scope of the utility model is defined by the appended claims and the equivalents thereof.

Claims (3)

1. a kind of point-and-shoot multimeter, including input port (1), partial pressure dropping resistor (2), protection converter (3), A/D conversion Circuit (4), main power source (5), LCD display (6), it is characterised in that: the input port (1) and partial pressure dropping resistor (2) It is electrically connected, partial pressure dropping resistor (2) output end is connect with protection converter (3) input terminal, the protection converter (3) Output end is connect with A/D conversion circuit (4) input terminal, and A/D conversion circuit (4) output end and protection converter (3) input terminal Connection, partial pressure dropping resistor (2) output end are connect with A/D conversion circuit (4) input terminal, main power source (5) output end It is connect with A/D conversion circuit (4) input terminal, A/D conversion circuit (4) output end is connect with LCD display (6) input terminal.

2. a kind of point-and-shoot multimeter according to claim 1, it is characterised in that: the A/D conversion circuit (4) electrically connects It is connected to backup power source.

3. a kind of point-and-shoot multimeter according to claim 1, it is characterised in that: the A/D conversion circuit (4) electrically connects It is connected to pcb board.