CN104515902B - Universal meter with high voltage alarm function - Google Patents
Universal meter with high voltage alarm function Download PDFInfo
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- CN104515902B CN104515902B CN201310453561.2A CN201310453561A CN104515902B CN 104515902 B CN104515902 B CN 104515902B CN 201310453561 A CN201310453561 A CN 201310453561A CN 104515902 B CN104515902 B CN 104515902B
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Abstract
The invention discloses the universal meter with high voltage alarm function, comprising：Digital electric meter, for the measurement pattern selected according to the user, electrical on the determinand is coupled feed-in by switch by input in a corresponding manner, pass through electronic switch input current potential corresponding to voltage divider acquirement, to be adapted to simultaneously feed-in after analog/digital converter processing, numerical value is calculated via controller, and the numerical value is shown by display device；Comparison circuit, for compared with the absolute value of the preset limit value, when the absolute value of the corresponding input current potential is bigger than the absolute value of the preset limit value, the absolute value of the corresponding input current potential to be produced into high pressure cue；Alarming device, the enable alarming device, reminds the user to pay attention to when the controller receives the high pressure cue of high logic level.The present invention selectable alarm mechanisms allow universal meter to be automatically reminded to user, avoid the damage of equipment, improve the security used.
Description
Technical field
It is particularly a kind of that there is high voltage warning (High Voltage Alarm) work(the present invention relates to a kind of digital electric meter
Universal meter (the Digital Multi-Meter of energy: DMM）.
Background technology
The measurement range of in general universal meter, by taking 4000 count product as an example, about between 400 millivolts
(mV) to 4000 volts, 40 micromicroamperes (μ A) to 4 amperes and 40 ohm (Ω) between 40 megohms (M Ω), its scope
Selection can be carried out with rotating disk or scope selection key, to the measurement pattern (measurement of voltage, electric current and resistance
Mode selection), can be carried out with rotating disk, and the selection of measurement range can with automatic (auto range) or manually
Mode is carried out.There are several different measurement patterns, such as DC voltage (DCV), alternating voltage (ACV), DC current (DCA)
And alternating current (ACA)-with direct current (DC) or exchange (AC) measures voltage and current.Recently have what some new developments came out
Digital electric meter adds the measurement pattern of electric capacity and frequency, and its measurement range can be that 4 how faraday (nF) is to 40 millifarads respectively
Draw (mF) and 4 hertz (Hz) to 40 megahertzs (MHz).When measurement frequency, there are some patterns to be used for measuring week
Phase (Duty Cycle), in addition, even if having selected ACV or ACA as measurement pattern, digital electric meter can also measure frequency simultaneously
Rate.The 4000V shelves of general ammeter, usual maximum can measure 1000V, have minority to measure 1500V.
As described above, in general universal meter also contains measurement resistance, electric capacity, the function of diode, some general-purpose electricity
Table has then additionally comprised frequency and duty cycle or the measurement function of temperature.User is by rotating the rotating disk on ammeter
(rotation knob) and button of arranging in pairs or groups select the range or function that it to be performed.Its principle is referred to as the U.S. is special
Disclosed by profit number the 8093516th, 6731102,7034517,6094045.When rotating disk rotates, and can drive related in ammeter
Mode switch, it is switched to corresponding position, by metal contact produce electrical connection, to produce corresponding survey
Loop is measured, this is the function of general universal meter (Multi-Meter) and the principle of its running.
Because the function of universal meter is numerous, for not being very extensive known user to electrical knowledge for one,
Or for the various unknown situations that may be faced in actual use, during measurement, user is to unknown electricity
Source or unknown determinand measure, and are possible to judge the electrical of determinand institute band by accident at the very start really.Along with if it makes
Mode is incorrect, after determinand is electrically coupled to the ammeter, has other affairs temporarily and continues ammeter
It is connected on unknown electrical determinand, if determinand now has a high voltage, and determinand connection is plant area or built
Thing power supply is built, caused by this situation, gently then causes instrument to burn, voltage instantaneous that is heavy then causing building or the power supply of plant area
Decline, in some instances it may even be possible to cause to jump electricity.In another example if a determinand is the voltage source (voltage of an exchange (AC)
Source), and user is not aware that, based on erroneous cognition or faulty operation, and ammeter is switched to the survey of DC voltage
File position is measured, to be measured to this signal source.Now measure be probably one level off to zero numerical value.If this, no
The value only measured be it is wrong (be mistaken for one level off to zero DC voltage), also user can be allowed to take for the determinand
There is no voltage (or voltage level off to zero), cause it to take for body contact and there will not be danger, but in fact this alternating voltage
Amplitude may be quite big, contactee can be allowed to have by the danger of electricity wound, or even jeopardize personal safety.
In another example capacitance measurement, because electric capacity electric discharge needs the release of one section of discharge time progress electric charge, in power system
Bulk capacitor used in (power system) generally requires longer discharge time, when power-supply system is just closed,
Capacitance charge is not bled off also completely, high voltage on electric capacity sometimes also be present., equally may be right if now going to measure capacitance
Instrument or ammeter cause damage, even cause Personal Risk.And bulky capacitor measurement is usually low input impedance in ammeter, when
There is high voltage in capacitor, and when time of measuring is too long, just easily cause the damage of ammeter, or even Personal Risk occurs.Example again
Such as, in ammeter, the input for measuring electric current is generally also Low ESR, if user, when measuring voltage, mistake will be measuring
Probe be inserted in measurement electric current slot on, when measuring between it is too long when, easily cause blown fuse, also easily cause ammeter
Damage.
The content of the invention
In view of this, the technical problem to be solved in the present invention is to provide a kind of general-purpose electricity with high voltage alarm function
Table, improve the security used.
In order to solve the above technical problems, the technical proposal of the invention is realized in this way：
A kind of universal meter with high voltage alarm function, in user with the input electrical couplings of the universal meter
During to determinand, if the absolute value for the current potential that the determinand has exceedes the absolute value of the preset limit value of the universal meter,
The universal meter can remind the user to pay attention to, the universal meter comprises at least：Digital electric meter, for being selected according to the user
Measurement pattern, in a corresponding manner switch will on the determinand it is electrical by input couple feed-in, pass through electronic cutting
Input current potential corresponding to voltage divider acquirement is closed, to be adapted to simultaneously feed-in after analog/digital converter processing, via controller
Numerical value is calculated, and the numerical value is shown by display device；And comparison circuit, for by this it is corresponding input current potential absolute value
It is bigger than the absolute value of the preset limit value in the absolute value of the corresponding input current potential compared with the absolute value of the preset limit value
When, high pressure cue is produced, the absolute value of default limit value is the exhausted of the full scale voltage value than the analog/digital converter
To being worth also big value；And alarming device, enable police when the controller receives the high pressure cue of high logic level
Showing device, the user is reminded to pay attention to.
Preferably, the comparison circuit comprises at least：Input node respective switch, according to user selection
Measurement pattern, allow controller to drive the input node respective switch in the comparison circuit to be done and switch, make corresponding input node
Respective switch turns on, to obtain the corresponding input current potential；Comparator, the input node respective switch is electrically coupled to obtain this
It is corresponding to input current potential to compare with the preset limit value；And logic gate, it is electrically coupled to the output of the comparator and produces height
Cue is pressed, when the absolute value of the corresponding input current potential is more than the absolute value of the preset limit value, the high pressure cue
For high logic level.
Preferably, the comparator comprises at least window type comparator, big in the absolute value of the corresponding input current potential
When the absolute value of the preset limit value, two output ends of the window type comparator at least one high logic level can be presented.
Preferably, the logic gate is logic sum gate, to receive the output of the comparator, and it is corresponding defeated at this
When entering the absolute value of current potential and being more than the absolute value of the preset limit value so that the output of the comparator at least one is that high logic is accurate
Position, and make the high pressure cue be high logic level.
Preferably, the universal meter further includes：Protection circuit, signal source circuit and frequency calculation circuit,
The controller selects appropriate divider resistance in the divider by the electronic switch, is suitable for the analog/digital turn to produce
The corresponding input current potential of parallel operation processing, it is resistance measurement pattern that the signal source circuit, which is used to the user select measurement pattern,
When capacitance measurement pattern or diode measurement pattern, be used as current source, with by the protection circuit and accordingly corresponding
The corresponding input current potential is produced in input node, the electronic switch, the signal source circuit, the comparison circuit, the analog/digital turn
Circuit, the controller and the frequency calculation circuit is changed to be made in integrated circuit form.
Preferably, the alarming device comprises at least visual alarm device, sense of hearing alarming device and tactile police
Showing device, wherein the visual alarm device are light-emitting device, and the sense of hearing alarming device is sound-producing device, and the tactile alerts device is
Shaking device.
Preferably, the visual alarm device comprises at least bulb and LED, and the sense of hearing alarming device comprises at least
Buzzer, the tactile alerts device comprise at least vibrating motor.
Another technical solution provided by the invention：A kind of universal meter with high voltage alarm function, in user
When being electrically coupled to determinand with the input of the universal meter, if the absolute value for the current potential that the determinand has exceedes the general-purpose
During the absolute value of the preset limit value of ammeter, the universal meter can remind the user to pay attention to, the universal meter comprises at least：Number
Word ammeter, for the measurement pattern selected according to the user, switch will be electrically logical on the determinand in a corresponding manner
Input coupling feed-in is crossed, controller is by electronic switch input current potential corresponding to voltage divider acquirement, to be adapted to simultaneously feed-in
After analog/digital converter processing, numerical value is calculated by controller, and the numerical value is shown by display device, the controller
Appropriate divider resistance is selected in the divider by electronic switch, is suitable for analog/digital converter processing to produce
The corresponding input current potential；And comparison circuit, for by the absolute of absolute value and the preset limit value of the corresponding input current potential
Value compares, and when the absolute value of the corresponding input current potential is bigger than the absolute value of the preset limit value, produces high pressure cue, writes from memory
The absolute value for recognizing limiting value is the also big value of the absolute value of the full scale voltage value than the analog/digital converter, and this is more electric
Road comprises at least input node respective switch, according to the measurement pattern of user selection, allows the controller to drive this more electric
Input node respective switch in road, which is done, to be switched, and is turned on corresponding input node respective switch, is electrically coupled to the partial pressure
Device obtains the corresponding input current potential to the electronic switch；And alarming device, the controller receive being somebody's turn to do for high logic level
Enable alarming device during high pressure cue, reminds the user to pay attention to.
Preferably, the comparison circuit further includes：Comparator, be electrically coupled to the input node respective switch with
The corresponding input current potential is obtained according to this with the preset limit value to compare；And logic gate, it is electrically coupled to the output of the comparator
And high pressure cue is produced, and when the absolute value of the corresponding input current potential is more than the absolute value of the preset limit value, the high pressure
Cue is high logic level.
Preferably, the comparator comprises at least window type comparator, big in the absolute value of the corresponding input current potential
When the absolute value of the preset limit value, two output ends of the window type comparator at least one high logic level can be presented.
Preferably, the logic gate is logic sum gate, to receive the output of the comparator, and it is corresponding defeated at this
When entering the absolute value of current potential and being more than the absolute value of the preset limit value so that the output of the comparator at least one is that high logic is accurate
Position, and make the high pressure cue be high logic level.
Preferably, the automatic warning ammeter further includes：Protection circuit, signal source circuit and frequency calculation electricity
Road, it is resistance measurement pattern that the signal source circuit, which is used to the user select measurement pattern, capacitance measurement pattern or diode are surveyed
During amount pattern, it is used as current source, it is corresponding defeated accordingly to produce this in corresponding input node by the protection circuit
Enter current potential, the electronic switch, the signal source circuit, the comparison circuit, the A/D conversion circuit, the controller and should
Frequency calculation circuit is made with the pattern of integrated circuit.
Preferably, the alarming device comprises at least visual alarm device, sense of hearing alarming device and tactile police
Showing device, wherein the visual alarm device are light-emitting device, and the sense of hearing alarming device is sound-producing device, and the tactile alerts device is
Shaking device.
Preferably, the visual alarm device comprises at least bulb and LED, and the sense of hearing alarming device comprises at least
Buzzer, the tactile alerts device comprise at least vibrating motor.
The technique effect that the present invention reaches is as follows：The present invention has the universal meter of high voltage alarm function, in measurement not
When knowing electrical object, an alarm function is provided in universal meter, measured value is wanted different from its gear when detecting
During voltage, it is possible to send warning to user immediately, to lift security when user measures, and this is also helpful
In the service life for extending ammeter.
Brief description of the drawings
Fig. 1 is the functional block diagram for the universal meter for having high voltage alarm function according to the present invention；
Fig. 2 is an embodiment of the universal meter for having high voltage alarm function according to the present invention, wherein display portion electricity
Lu Weijie circuit structure diagram；
Fig. 3 is that an embodiment of the universal meter for having high voltage alarm function according to the present invention is performing voltage measurement
When, signal partial pressure is performed with detecting the embodiment of dividing point current potential;
Fig. 4 A are that an embodiment of the universal meter for having high voltage alarm function according to the present invention is performing resistance measurement
When, the embodiment of detection determinand current potential；
Fig. 4 B are that an embodiment of the universal meter for having high voltage alarm function according to the present invention is performing capacitance measurement
When, the embodiment of detection determinand current potential；And
Fig. 4 C are that an embodiment of the universal meter for having high voltage alarm function according to the present invention is surveyed in execution diode
During amount, the embodiment of determinand current potential is detected.
【Symbol description】
First ~ the 4th input：INPUT1 ~ INPUT4
First ~ the 5th mode switch：MODE SWITCH1 ~ MODE SWITCH5
Earth terminal: COM
Divider resistance：Rd1~ Rd4
Voltage conversion resistance：Rt1 and Rt2
Node：n1~ n9
The resistance of voltage conversion circuit：R1~ R8
The resistance of voltage conversion circuit：D1, D2
Switch：SW1~SW11
First comparator：CMP1
Second comparator：CMP2
P-type metal-oxide half field effect transistor：PMOS1
First operational amplifier：OP1
Source resistance：Rs1
HV：High pressure cue
Resistance R*
Electric capacity C*
Diode：D*I
Fuse：F1 F2
100：Mode switch
200：Input
300：Protection circuit
400：Divider
500：Voltage conversion circuit
600：Analog/digital converter
700：Controller
800：Electronic switch
900：Signal source circuit
950：Display device
1000：Comparison circuit
1100：Alarming device
1105：Visual alarm device
1106：Sense of hearing alarming device
1107：Tactile alerts device
1150：Integrated circuit
1120：Frequency calculation circuit
1190：Liquid crystal display.
Embodiment
Here, the present invention will be described in detail with reference to follow-up specific embodiment, and these embodiments are used only to solve
The present invention is said, conversely, the present invention is not limited within the scope of these embodiments.
Explain that being used in universal meter according to a preferred embodiment of the invention (also has referred to as numeral electricity with Fig. 1 first
Table) in functional block diagram, user in mode switch 100 select its think the determinand to be measured it is electrical (or other
Physical property such as temperature etc.), by the electrical couplings of input 200 (or being connected to) in universal meter to determinand, now protect
Protection circuit 300 is to pass through one group of mode switch being selected in mode switch 100, and circuit turn-on is formed with input 200.Point
Depressor 400 and voltage conversion circuit 500, then it is the magnitude of voltage according to input, there is provided corresponding input voltage to analog/digital
Converter 600, it is then communicated to controller 700.After corresponding input voltage takes partial pressure, it is set to be no more than analog/digital conversion
The full scale of device 600 (full scale) magnitude of voltage, could so allow and be handled for analog/digital converter 600 and produce a numerical value.
To electronic switch 800 it is some passive device measurement patterns by the sense ends of signal source circuit 900 to protection circuit 300
Under corresponding input current potential, it, which is sent to analog/digital converter 600 and can also provide it, is converted into a numerical value.Then will
The numerical value is sent to display device 950, and the numerical value is read to be shown to user., can also if detecting abnormal voltage
OL (Over Limit) is shown on display device 950.Described above is the general-purpose electricity according to the preferred embodiment of the present invention
Function mode when table is used to measure determinand, and how to detect determinand at it and whether have and exceed universal meter of the present invention
When the chosen pattern to be measured gives tacit consent to extreme voltage values to be processed, its operation principles is as described in next section.
It is that dividing point (namely mode switch is detected with one group of comparison circuit 1000 in presently preferred embodiments of the present invention
In 100 output end) voltage swing, and benchmark current potential can be according to the full scale of analog/digital converter 600
(full scale) magnitude of voltage and stipulate, take a value also big compared with the full scale voltage value come as compare benchmark electricity
Position.If such as the full scale voltage value is 1 volt, the absolute value that benchmark current potential can be taken be it is big, such as 1.5 volts,
When the absolute value of the current potential of dividing point is more than 1.5 volts, then the output signal HV of comparison circuit 1000 becomes high potential, and this is high
Current potential causes controller 700 by the enable of alarming device 1100, to alert user, to let the user know that the voltage of now input
Value alreadys exceed the treatable limit of this system institute.And in the preferred embodiment of the present invention, this alarming device 1100 can be with
Include visual alarm device 1105, sense of hearing alarming device 1106 and tactile alerts device 1107.Visual alarm device 1105 can
Can include buzzer (BUZZER) etc. comprising the light-emitting device such as LED or conventional bulb, sense of hearing alarming device 1106 and can send out
Go out the device of sound, and tactile alerts device 1107 can include the device that the touch feelings such as vibrating motor obtain.Because this hair
The universal meter with high pressure alarm function of a bright preferred embodiment can be extremely short after contact measured thing time (less than
One millisecond) in, differentiate the determinand whether have exceed universal meter of the present invention it is chosen to measure pattern and give tacit consent to want
The maximum voltage value of processing, if so, then proposing various warnings to user immediately, and OL (Over are shown in display device
Limit).So have the universal meter of high pressure alarm function according to presently preferred embodiments of the present invention, on there will be no
The potentially danger of conventional digital ammeter.In Fig. 1, generally known universal meter (digital electric meter) can be included except comparing
Remaining all or part of component outside circuit 1000 and alarming device 1100, to be used to designed by Main Basiss universal meter
Measurement which electrically has depending on.And the preferred embodiment of the present invention is the more upper ratio outside known digital electric meter
Compared with circuit 1000 and alarming device 1100, to reach the alarm function of the invention to be accomplished.
It will be further described below with Fig. 2, circuit element (such as resistor, electric capacity shown by circuit diagram therein
The circuit element such as device and diode and device) and its connected mode be only intended to explain the present invention a preferred embodiment be used,
The modus operandi of the present invention is not limited to disclosed by this figure.
As shown in Figure 2,（The second inputs of first input end INPUT1/ INPUT2/COM corresponds to Fig. 1 input
200, R1 ~ R8/D1/D2/F1/F2 corresponds to Fig. 1 protection circuit 300, and wherein F1 and F2 is fuse, first mode switch
The mode switch of (MODE SWITCH1) ~ 5th (MODE SWITCH5) corresponds to Fig. 1 mode switch 100, Rd1 ~ Rd4
Fig. 1 divider 400 is corresponded to, Rt1 and Rt2 corresponds to Fig. 1 voltage conversion circuit 500.Wherein, voltage/frequency and duty
Cycle/ resistance/diode/electric capacity is then inputted using first input end INPUT1, current measurement（A）Use input jack
Two input INPUT2 are inputted, small current measurement（mA）Inputted using the 3rd input INPUT3, and temperature survey then makes
Inputted with the 4th input INPUT4.
To save the volume and cost of circuit, realizing the circuit of partial function can be formed with integrated circuit, in this reality
Apply in example, these circuits can include：Controller 700, analog/digital converter 600, electronic switch 800, signal source circuit
900th, comparison circuit 1000 and frequency calculation circuit 1120, can use same integrated circuit above（IC）1150 make, such as
The element that dotted line frame in Fig. 2 is included.
When an embodiment of the universal meter according to the present invention with high voltage alarm function is performing the voltage of determinand
During measurement, the measured signal on determinand is inputted by first input end INPUT1, and first mode switch MODE SWITCH 1 are arrived
5th mode switch MODE SWITCH 5 are to close (OFF), and voltage signal inputs via resistance R1.Due in general electricity
Pressure signal magnitude is well over 600 manageable scope of analog/digital converter, therefore input signal needs first to do partial pressure.
Typically in ammeter, the conventional dividing ratios of voltage measurement have 1/10,1/100,1/1000 and 1/10000, the electricity after partial pressure
Position must be less than the full scale of analog/digital converter 600（full scale）, otherwise will exceed measurable range, after it is changed
Numerical value will be shown as OL.
In voltage measuring mode, controller 700 can be by electronic switch 800, in the divider resistance Rd1- of divider 400
Select appropriate divider resistance to be connected to R1 in Rd4, to produce appropriate partial pressure potential in n2 nodes, further pass through electricity afterwards
The switching of sub switch 800, the current potential of n2 nodes is sent in analog/digital converter 600, to be converted into numerical value.With this hair
Partial circuit diagram in a bright embodiment is shown in Fig. 3, and above-mentioned action is described further.When execution voltage measurement
When, controller 700 can drive one in electronic switch 800 (comprising switch SW1-SW5), such as switch SW1 conductings (ON), this
When to node n2 obtain original signal 1/10 partial pressure, controller 700 can further drive switch SW5 conducting, now due to
The relation of resistance ratio, the current potential of n2 nodes are changed into the 1/10 of input signal.
For the example of above-mentioned measurement voltage, the mode typically operated is as follows：If analog/digital converter 600 is expired
Scale is 1V, and the measured signal inputted is 200V signal, at the beginning, the range set of measurement in lowest gear, this
When dividing ratios be 1/10, the n2 node potentials after this partial pressure are 20V, due to the full quarter more than analog/digital converter 600
Spend, the numerical value meeting OL after conversion, now controller 700 can drive the gear of measurement up to jump one grade, and now controller 700 also can
Control electronic switch 800 does and switched, and the switch SW5 that will connect R1 and Rd1 in Fig. 3 originally closes (OFF), and will connection R1 with
Rd2 switch SW4 conductings so that the dividing ratios of this gear are changed into 1/100, now input the current potential of analog/digital converter
2V is reduced into, current potential of the measured signal now inputted in corresponding input node n2 is 2V, still more than analog/digital conversion
The full scale of device 600, it is therefore necessary to up jump one grade again, now controller 700 can control electronic switch 800 to do again and switch, will
SW4 closes (OFF), and SW3 is turned on into (ON), by signal partial pressure is script 1/1000, produces 200mV signal, this
When the measured signal that inputs corresponding input node n2 current potential already below analog/digital converter 600 full scale, at this moment
This current potential is delivered to analog/digital converter 600 and changed by time, can just obtain a correct numerical value.General traditional ammeter
Although having this automatic tripping to select the function of appropriate divider resistance, most of all, its user must be voluntarily in electricity
It is DC voltage or alternating voltage to select the measurement pattern to be carried out on table with button or rotating disk.If user selects wrong measurement mould
Formula, for example, AC voltage profile is selected on ammeter to measure, but user is but unknown to measured determinand
A d. c. voltage signal with+200V in fact, then what measurement result was shown be probably one close to zero numerical value, and allow
User have ignored potential danger.Therefore if user thinks that the determinand does not have voltage and goes to touch, it is possible to electric
Wound.
The shortcomings that above tradition ammeter, it can't occur in the present invention, because being with one group of comparison circuit in the present invention
1000 detect dividing point (corresponding input node) n2-n8 signal magnitude (voltage quasi position), and itself and benchmark current potential are done
Compare.Benchmark current potential can be according to the electricity of the full scale (full scale) for the analog/digital converter 600 to be used
Pressure value and order, and take one group of value also bigger than the magnitude of voltage.For example, if the voltage of its full scale (full scale)
It is worth for 1V, then can uses two comparators, its comparison current potential is ordered in+1.5V and -1.5V respectively, if the current potential of dividing point is high
In+1.5V, or during less than -1.5V, in other words, if the current potential absolute value of dividing point (corresponding input node) is more than 1.5, compare
Compared with the output signal of circuit 1000, namely HV, high logic level (Logic High) can be changed into, the signal of this state delivers to control
After device 700, Fig. 2 is refer to, meeting enable (Enable) alarming device 1100, in other words, controller 700 is being High when HV signals
When, the sounding of sense of hearing alarming device 1106 can be driven, and light visual alarm device 1105.To be shown in one embodiment of the invention
In Fig. 3 part, when carrying out voltage measurement to reality, its mode acted is described further.When performing voltage measurement, control
Device 700 processed can transmit one group of benchmark current potential to comparison circuit 1000, and comparison current potential in this instance is+1.5V and -1.5V
(absolute value 1.5), in voltage measuring mode, controller 700 can turn on the respective switch SW6 in comparison circuit 1000
(ON), and make switch SW7 ~ SW11 close (OFF), if voltage possessed by determinand is+200V, in other words, input signal for+
200V DC voltage, but user misapplies AC voltage profile and measured, the numerical value now measured close to zero, due to
This does not have OL close to zero numerical value, therefore controller 700 can't drive gear up trip stop, and the scope of measurement can be parked in most
Low-grade location, the dividing ratios of lowest gear are 1/10, now corresponding dividing point（N2 nodes）For 20V DC voltage letter
Number, this current potential absolute value (20V) is due to the comparison current potential higher than+1.5V (absolute value 1.5), and now first comparator CMP1's is defeated
High can be changed into by going out, further such that HV signals are changed into High, HV signals send (in the 3rd figure) controller 700, controller back to
700 can drive the sounding of sense of hearing alarming device 1106, and light visual alarm device 1105, and/or allow tactile alerts device
1107 vibrations, therefore can reach the effect of warning.
In short, the preferred embodiment according to the present invention, comparison circuit 1000 are contained corresponding to corresponding input node
N2-n8 respective switch SW6-SW11, a window type comparator (including first comparator CMP1 and the second comparator CMP2) and
One logic sum gate (OR gate).Wherein first comparator CMP1 non-inverting input is electrically coupled to the second comparator CMP2
Inverting input, and first comparator CMP1 inverting input, then be fed into be measured so that this ammeter is chosen
Pattern give tacit consent to maximum voltage value to be processed (such as 1.5V) on the occasion of+1.5V, and the second comparator CMP2's is noninverting defeated
Enter end and be then fed into and be selected with this ammeter the pattern to be measured gives tacit consent to maximum voltage value to be processed (such as 1.5V)
Negative value -1.5V.When respective switch SW6-SW11 is transferred to the absolute value of the voltage of the input of window type comparator, than to be surveyed
The pattern of amount is given tacit consent to the absolute value also hour of ceiling voltage to be processed, and first comparator CMP1 and the second comparator CMP2 are
Can all be negative saturation, in other words, output can all be just low logic level (L), so logic sum gate OR two inputs are all low
Logic level (L), so logic sum gate OR output signal HV is exactly low logic level (L).
When the respective switch SW6-SW11 in comparison circuit is transferred to the absolute value of the voltage of the input of window type comparator,
Than the pattern to be measured give tacit consent to ceiling voltage to be processed absolute value it is also big when, first comparator CMP1 and second ratio
Compared with device CMP2, at least one can be positive saturation, and in other words, it is high logic level (H) to export at least one, thus logic or
At least one is high logic level (H) among door OR two inputs, so logic sum gate OR output signal HV is exactly high
Logic level (H).When HV is high logic level (H), Fig. 2 is refer to, controller 700 will enable sense of hearing alarming device 1106
And/or visual alarm device 1105 and/or tactile alerts device 1107, and OL is shown on liquid crystal display 1190, with
User is proposed to warn.
Illustrate below when determinand is passive device（Resistance/diode/electric capacity）When, one according to the present invention preferably implements
The ammeter of example, how is the mode that it is operated, so that having the ability to be selected to enter more than universal meter of the present invention in determinand current potential
When the pattern of row measurement gives tacit consent to extreme voltage values to be processed, warning can be sent to user automatically.Please continue to refer to Fig. 2,
When execution passive device（Resistance/diode/electric capacity）During measurement, determinand is inputted by first input end INPUT1, first mode
It is ON to switch (MODE SWITCH 1), and it is OFF that second mode, which is switched to the 5th mode switch (MODE SWITCH 2-5),.In quilt
In dynamic element measurement pattern, corresponding input node is n3 and n4, and node n3 is force ends, and node n4 is sense ends.Work as progress
During measurement, signal source circuit 900 can pass through thermistor（Positive Temperature Coefficient Resistor:
PTC）R3, applying a voltage or electric current to determinand, R2 is the resistance of protection body circuit, in the design of circuit, electricity
Stream does not flow through resistance R2, therefore the current potential of n4 nodes is equal to the current potential on determinand, and comparison circuit 1000 then passes through node
N4 detects the current potential of determinand, if detecting abnormal voltage, in other words, the absolute value of corresponding input node n4 potential value
More than 1.5, then HV signals can be changed into High, and now controller 700 can drive the sounding of sense of hearing alarming device 1106, and put photopic vision
Alarming device 1105, and/or allow tactile alerts device 1107 to shake, therefore can reach the effect of warning.
When according to the present invention have high voltage alarm function universal meter an embodiment perform determinand be resistance
Measurement when, Fig. 4 A are refer to, wherein the first operational amplifier OP1, p-type metal-oxide half field effect transistor PMOS1, source resistance
Rs1, these are all the somes of signal source circuit 900, and it forms a typical current source circuit, wherein, change source electrode electricity
Resistance Rs1 size can change the output size of current source, with response to different resistance measurement scopes.Current source flows through source electrode electricity
R3 and testing resistance R* is hindered, and a current potential is produced on testing resistance R*, n4 nodes are end of probe, and the current potential of n4 nodes is equal to
Current potential on determinand, in the present embodiment, namely the current potential of corresponding input node, this potential value are transmitted by electronic switch 800
To analog/digital converter 600, then the voltage value on determinand R* is can obtain, controller 700 is by voltage value divided by electric current
The size in source can converse determinand R* resistance value, the numerical value of electric current to be measured can be calculated by controller 700, then
This numerical value is sent to liquid crystal display 1190 again.The universal meter for the preferred embodiment according to the present invention is used to survey above
Measure function mode of determinand when be resistance, and whether determinand how is detected with exceeding universal meter quilt of the present invention at it
When the selected pattern to be measured gives tacit consent to extreme voltage values to be processed, its operation principles is as described below：In such a mode,
If adding+1V current potential in OP1 positive input terminal, the current potential of n10 nodes will be then because the characteristic of the negative recovery of OP1, will extremely connect
Closely+1V, if the current potential of n9 nodes is+3V and Rs1 resistance is 200K ohms, now the size of current of current source is 10uA.
Under normal measuring state, the current potential on determinand should be on the occasion of and the maximum current potential+1V that current source is not to be exceeded is minimum
It is then close to 0V.According to the universal meter of the preferred embodiment of the present invention, in resistance measurement pattern, controller 700 can drive
The switch in comparison circuit 1000 is made to switch, now the comparator in comparison circuit 1000 by detect n4 nodes current potential whether
It is abnormal, if the current potential that the current potential of n4 nodes is higher by current source is excessive, or it is excessive less than 0V, then it is considered as exception, represents now
The probe of input may touch the voltage of an exception, in other words, the now determinand R* of input institute electrical couplings
Electrically already exceed the chosen pattern to be measured of universal meter of the present invention and give tacit consent to maximum voltage value to be processed.Scheming
In 4A institutes illustrated example, compare current potential for+1.5V and -1.5V, if the current potential of n4 nodes changes speech higher than+1.5V or less than -1.5V
It, absolute value is more than 1.5, then HV signals can be changed into High, and now controller 700 can be according to the output signal of comparison circuit 1000
Start alarm mechanisms for high logic level.
When according to the present invention have high voltage alarm function universal meter an embodiment perform determinand be electric capacity
Measurement when, refer to Fig. 4 B, current source flows through resistance R3 and testing capacitance C*, and electric capacity current potential, can be by with the inflow of electric current
Gradually become big, this current potential is sent to analog/digital converter 600 via (in Fig. 2) electronic switch 800, the then basis of controller 700
Current potential can converse determinand C* capacitance to the variation relation of time, and then this numerical value is sent to liquid by controller 700 again
Crystal display 1190.Be above according to the present invention a preferred embodiment universal meter be used for measure when determinand is electric capacity
Function mode, and how to detect whether determinand has more than the chosen mould to be measured of universal meter of the present invention at it
When formula gives tacit consent to extreme voltage values to be processed, its operation principles is as described below：In such a mode, in capacitance measurement pattern,
Controller 700 can drive the switch in comparison circuit 1000 to do to switch, and now the comparator in comparison circuit 1000 will detect n4
Whether the current potential of node is abnormal, if the current potential that the current potential of n4 nodes is higher by current source is excessive, or it is excessive less than 0V, then it is considered as different
Often, the voltage of an exception may be touched by representing the probe of input now, in other words, now input institute electrical couplings
Determinand C* electrically already exceed universal meter of the present invention be selected the pattern to be measured give tacit consent to it is to be processed most
High-voltage value, the current potential that exception on a voltage source, or electric capacity be present may be touched by representing the probe of now input.
In Fig. 4 B institutes illustrated example, compare current potential for+1.5V and -1.5V, if the current potential of n4 nodes higher than+1.5V or less than -1.5V,
HV signals can be changed into High, and now controller 700 can start according to the output signal of comparison circuit 1000 for high logic level
Alarm mechanisms.
When according to the present invention have high voltage alarm function universal meter an embodiment perform determinand be two poles
During the measurement of pipe, Fig. 4 C are refer to, now signal source circuit 900 applies+1V voltage source to thermistor R3, if two poles
Pipe turns on, then the current potential of end of probe n4 nodes is+0.7V or so, if being not turned on, the current potential of n4 nodes is then+1V, n4 nodes
Current potential is sent to analog/digital converter 600 via electronic switch 800, then can try to achieve diode D* conducting current potential, this current potential
Normal measuring state also be on the occasion of.In diode measurement pattern, controller 700 can drive holding in comparison circuit 1000
Pass, which is done, to be switched, and now whether the comparator in comparison circuit 1000 is abnormal by the current potential for detecting corresponding input n4 nodes, if n4 is saved
The current potential that the current potential of point is higher by voltage source is excessive or excessive less than 0V, then is considered as exception, and the probe for representing now input can
The voltage of an exception can be touched.In other words, now the electrical of the diode D* of input institute electrical couplings alreadys exceed this
Invention universal meter is selected the pattern to be measured and gives tacit consent to maximum voltage value to be processed, in Fig. 4 C embodiment,
Compare current potential for+1.5V and -1.5V, if the current potential of n4 nodes higher than+1.5V or can be changed into High less than -1.5V, HV signals,
Now controller 700 can start alarm mechanisms according to the output signal of comparison circuit 1000 for high logic level.
When letter of the embodiment according to universal meter of the present invention with high voltage alarm function on determinand is performed
Number frequency or duty cycle measure when, refer to Fig. 2, measured signal is inputted by first input end INPUT1, second mode
Switch MODE SWITCH2 are ON, first mode switch MODE SWITCH1 and the 3rd mode switch MODE SWITCH3 to the 5th
Mode switch MODE SWITCH5 are OFF, and comparison circuit 1000 has in the current potential that this measurement pattern mainly detects resistance R5
It is without exception.Diode D1 and D2 is OFF, now due to no electric current on R5, n5 nodes and earth terminal when in general measures
Between there is no voltage difference, therefore its voltage is equal to 0V.When first input end INPUT1 inputs a very big positive voltage, two poles
Pipe D2 can produce collapse (break down), and diode D1 can also be turned on, and now resistance R5 meetings inflow current accordingly to input
N5 nodes produce a positive voltage；And when first input end INPUT1 inputs a very big negative voltage, diode D1 can be produced
Raw break down, diode D2 can also be turned on, and now resistance R6 can flow out electric current and accordingly to input n5 nodes generation one
Negative voltage.And in the preferred embodiment according to the present invention how under this measurement pattern, whether determinand is detected with super
Cross universal meter of the present invention and be selected the pattern to be measured when giving tacit consent to extreme voltage values to be processed, its operation principles is such as
It is lower described：In such a mode, under frequency or duty cycle measurement patterns, controller 700 can be driven in comparison circuit 1000
Switch do and switch, now whether the comparator in comparison circuit abnormal such as high by the current potential for detecting corresponding input node n5
In+1.5V or during less than -1.5V, in other words, when absolute value is more than 1.5, then it is considered as exception, now HV signals are changed into High, control
Device 700 processed can start alarming device 1100 according to the output signal of comparison circuit 1000 for high logic level.
When electricity of the embodiment according to universal meter of the present invention with high voltage alarm function on determinand is performed
During flow measurement, measured signal is inputted by the second input INPUT2, and the 3rd mode switch MODE SWITCH3 are ON, first mode
Switch MODE SWITCH1 and second mode switch MODE SWITCH2 and fourth mode switch MODE SWITCH4 and the 5th mould
Formula switch MODE SWITCH5 are OFF.R6 is protection IC resistance, and the n6 nodes being connected with R6 are end of probe, is also execution
Corresponding input node when current measurement.Current signal to be measured flows through fuse F1 and resistance Rt1, this electric current and in Rt1
On be converted into a voltage signal, this voltage is sent to electronic switch 800 by n6 nodes, then by electronic switch 800 by this
Current potential is sent to analog/digital converter 600, convertible to obtain the numerical value of this voltage, and this numerical value is sent to controller 700, control
Device 700 processed can converse voltage value divided by Rt1 size the numerical value of electric current to be measured, and this numerical value then is sent into liquid again
Crystal display 1190.It is that the universal meter of the preferred embodiment of the foundation present invention is used for the function mode for measuring electric current above,
And its how to detect determinand whether have exceed universal meter of the present invention be selected the pattern to be measured given tacit consent to
During extreme voltage values to be processed, its operation principles is as described below：In such a mode, controller 700 can drive comparison circuit
Switch in 1000, which is done, to be switched, and now the comparator in comparison circuit is by probe node n6, i.e. the voltage of this corresponding measurement pattern
Whether the current potential inputted on n6 nodes abnormal, for example, higher than the comparator in comparison circuit 1000 benchmark current potential (+
1.5V) or less than the comparator in comparison circuit 1000 benchmark current potential (- 1.5V) when, it is in other words, corresponding to input n6 sections
(default value is the comparison base of the comparator in comparison circuit 1000 when current potential absolute value on point is more than default value 1.5V
The absolute value of quasi- current potential), then it is considered as exception, when this situation occurs, were it not for abnormal big electric current is exactly user in electricity
Misapplied under stream mode, caused by the amount of taking away voltage, now HV signals are changed into High, and controller 700 can be according to comparison circuit 1000
Output signal starts alarming device 1100 for high logic level.
When an embodiment of the universal meter according to the present invention with high voltage alarm function is small on determinand is performed
During current measurement, measured signal is inputted by the 3rd input INPUT3, and fourth mode switch MODE SWITCH4 are ON, the first mould
Formula switch MODE SWITCH1 to the 3rd mode switch MODE SWITCH3 and the 5th mode switch MODE SWITCH5 be OFF.
R7 is protection IC resistance, and the n7 nodes being connected with R7 are end of probe, this also corresponding input for execution when current measurement
Node.Current signal to be measured flows through fuse F2 and resistance Rt2, this electric current and a voltage is converted on resistance Rt2
Signal, this voltage is sent to electronic switch 800 by n7 nodes, then this current potential is sent into simulation/number by electronic switch 800
Word converter 600, convertible to obtain the numerical value of this voltage, this numerical value is sent to controller 700, and controller 700 is by voltage value
Divided by Rt2 size, the numerical value of electric current to be measured can be calculated by controller 700, this numerical value is then sent to liquid crystal again
Display 1190.It is that the universal meter of the preferred embodiment of the foundation present invention is used for the function mode for measuring electric current above, and
Its how to detect determinand whether have exceed universal meter of the present invention be selected the pattern to be measured give tacit consent to want
During the extreme voltage values of processing, its operation principles is as described below：In such a mode, controller 700 can drive comparison circuit 1000
In switch do and switch, now whether the comparator in comparison circuit 1000 abnormal by the current potential for detecting n7 nodes, for example, higher than
The benchmark current potential (+1.5V) of comparator in comparison circuit 1000 or the comparison less than the comparator in comparison circuit 1000
During reference potential (- 1.5V), in other words, the corresponding current potential absolute value inputted on n7 nodes is more than (described silent during default value 1.5V
Recognize the absolute value that value is the benchmark current potential of the comparator in comparison circuit 1000), then it is considered as exception, this situation occurs
When, were it not for abnormal big electric current is exactly that user misapplies under current-mode, caused by the amount of taking away voltage, now HV signals
It is changed into High, controller 700 can be according to output signal enable (Enable) warning for high logic level of comparison circuit 1000
Device 1100.
When temperature of the embodiment according to universal meter of the present invention with high voltage alarm function on determinand is performed
During degree measurement, thermocouple（thermocouple）Both ends can be inserted in the 4th input INPUT4 and COM, now the 5th pattern is opened
It is ON to close MODE SWITCH5, and it is OFF that first mode, which switchs MODE SWITCH1 to fourth mode switch MODE SWITCH4,.R8
To protect IC resistance, the node n8 being connected with R8 is end of probe, and this is also to perform corresponding input section when current measurement
Point.Thermocouple variation with temperature, can produce a voltage signal, and this voltage is sent to electronic cutting by accordingly inputting n8 nodes
800 are closed, then this current potential is sent to by analog/digital converter 600 by electronic switch 800, can obtain the voltage on thermocouple
Value, this numerical value reach controller 700, and controller converts via tabling look-up, and can obtain the temperature of determinand.It is according to this hair above
The universal meter of a bright preferred embodiment is used for the function mode for measuring determinand temperature, and how to detect determinand at it
During whether with giving tacit consent to extreme voltage values to be processed more than the chosen pattern to be measured of universal meter of the present invention, its
Operation principles are as described below：Under temperature measurement mode, controller 700 can drive the switch in comparison circuit 1000 to do to switch,
Now whether the comparator in comparison circuit is abnormal by the current potential for detecting corresponding input n8 nodes, such as higher than comparison circuit 1000
In comparator benchmark current potential (+1.5V) or less than the comparator in comparison circuit 1000 benchmark current potential (-
When 1.5V), in other words, (default value is to compare when the corresponding current potential absolute value inputted on n8 nodes is more than default value 1.5V
Compared with the absolute value of the benchmark current potential of the comparator in circuit 1000), then it is considered as exception, moreover under general status on thermocouple
Current potential should be very low, typically not greater than 0.1V, if there is this unusual condition to occur, it is likely to which user's imprudence is by heat
The conductive contact of galvanic couple is to voltage source.Now HV signals are changed into High, and controller 700 can be believed according to the output of comparison circuit 1000
Number for high logic level and enable (Enable) alarming device 1100.
Embodiment provided above covers the measurement function of general universal meter, can apply the preferable reality of the present invention
Example is applied, no matter and enabling universal meter that can there is high voltage automatic alarming function under which kind of measurement pattern.Also therefore only
If ammeter may be caused to damage, or dangerous situation can send the warning of various approach to user, so may be used
Promote security during measurement, and extend the service life of ammeter.
The foregoing is only a preferred embodiment of the present invention, is not intended to limit the scope of the present invention.
Claims (10)
1. a kind of universal meter with high voltage alarm function, is electrically coupled in user with the input of the universal meter
, should if the absolute value for the current potential that the determinand has exceedes the absolute value of the preset limit value of the universal meter during determinand
Universal meter can remind the user to pay attention to, it is characterised in that the universal meter comprises at least：
Digital electric meter, has first input end, the second input, the 3rd input and the 4th input, first mode switch,
Second mode switch, the 3rd mode switch, fourth mode switch and the 5th mode switch, for according to the user
The measurement pattern of selection, switch will be electrical by input coupling feed-in on the determinand in a corresponding manner, passes through electricity
Sub switch input current potential corresponding to voltage divider acquirement, to be adapted to simultaneously feed-in after analog/digital converter processing, via control
Numerical value is calculated in device processed, and shows the numerical value by display device, and the measurement pattern includes voltage measuring mode, resistance measurement mould
It is formula, diode measurement pattern, capacitance measurement pattern, frequency measurement pattern, work period measurement pattern, current measurement pattern, small
Current measurement pattern and temperature measurement mode；And
Comparison circuit, for by this it is corresponding input current potential absolute value compared with the absolute value of the preset limit value, it is corresponding at this
Input current potential absolute value it is bigger than the absolute value of the preset limit value when, produce high pressure cue, default limit value it is absolute
It is worth for the also big value of the absolute value of the full scale voltage value than the analog/digital converter；And
Alarming device, enable alarming device when the controller receives the high pressure cue of high logic level, reminding should
User pays attention to；
When user selection resistance measurement pattern, diode measurement pattern or capacitance measurement pattern a period of time, on the determinand
It is electrical inputted by first input end, and first mode switch for open, second mode switch, the 3rd pattern switching
Device, fourth mode switch and the 5th mode switch are to close；
It is electrical by the on the determinand when the user selects frequency measurement pattern or work period measurement pattern for the moment
One input is inputted, and second mode switch is opens, first mode switch, the 3rd mode switch, fourth mode are cut
Parallel operation and the 5th mode switch are to close；
When the user selects current measurement pattern, electrical on the determinand is inputted by the second input, and the 3rd mould
For formula switch to open, first mode switch, second mode switch, fourth mode switch and the 5th mode switch are equal
To close；
When the user selects small current measurement pattern, electrical on the determinand is inputted by the 3rd input, and the 4th
Mode switch is opens, first mode switch, second mode switch, the 3rd mode switch and the 5th mode switch
It is to close；
When the user selects temperature measurement mode, electrical on the determinand is inputted by the 4th input, and the 5th mould
For formula switch to open, first mode switch, second mode switch, the 3rd mode switch and fourth mode switch are equal
To close.
2. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that the comparison circuit
Comprise at least：
Input node respective switch, according to the measurement pattern of user selection, controller is allowed to drive defeated in the comparison circuit
Ingress respective switch, which is done, to be switched, and turns on corresponding input node respective switch, to obtain the corresponding input current potential；
Comparator, be electrically coupled to the input node respective switch with obtain this it is corresponding input current potential with the preset limit value ratio
Compared with；And
Logic gate, it is electrically coupled to the output of the comparator and produces high pressure cue, in the absolute of the corresponding input current potential
When value is more than the absolute value of the preset limit value, the high pressure cue is high logic level.
3. the universal meter according to claim 2 with high voltage alarm function, it is characterised in that the comparator is extremely
Window type comparator is included less, when the absolute value of the corresponding input current potential is more than the absolute value of the preset limit value, the window type ratio
Compared with device two output ends at least one high logic level can be presented.
4. the universal meter according to claim 2 with high voltage alarm function, it is characterised in that the logic gate is
Logic sum gate, to receive the output of the comparator, and it is more than the preset limit value in the absolute value of the corresponding input current potential
During absolute value so that the output of the comparator at least one is high logic level, and makes the high pressure cue accurate for high logic
Position.
5. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that in voltage measurement mould
Formula, the controller are selected appropriate divider resistance to be produced in corresponding input node and divided by the electronic switch in the divider
The corresponding input current potential of pressure, the partial pressure, which accordingly inputs current potential, must be less than the full scale of the analog/digital converter in terms of by controller
Calculation draws the numerical value, if the partial pressure accordingly inputs the full scale that current potential remains above the analog/digital converter, the controller enable
The alarming device.
6. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that wherein surveyed in resistance
Amount pattern, diode measurement pattern or capacitance measurement pattern for the moment, a signal source circuit by one first thermistor to this
Determinand applies a voltage or electric current, and corresponding input current potential is produced in corresponding input node, comes by the comparison circuit
The corresponding input current potential of the determinand is detected, it is bigger than the absolute value of the preset limit value in the absolute value of the corresponding input current potential
When, the controller enable alarming device.
7. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that wherein surveyed in frequency
For the moment, a frequency calculation circuit detects the determinand by one second thermistor for amount pattern or work period measurement pattern,
And second thermistor is electrically connected with the first diode and the second diode, first diode and the second diode are back-to-back
It is connected in series.
8. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that wherein surveyed in electric current
During amount pattern, the electric current of the determinand produces corresponding input electricity via one 0.05 ohm of resistor in corresponding input node
Position, if the corresponding input current potential is higher than full scale of the analog/digital converter, the controller enable alarming device, wherein
The voltage conversion circuit is one 0.05 ohm of resistor.
9. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that wherein in low current
During measurement pattern, the electric current of the determinand produces corresponding input electricity via one 50 ohm of resistor in corresponding input node
Position, if the corresponding input current potential is higher than the full scale of the analog/digital converter, the controller meeting enable alarming device.
10. the universal meter according to claim 1 with high voltage alarm function, it is characterised in that wherein in temperature
During measurement pattern, the determinand produces a corresponding input current potential via a thermocouple variation with temperature, if the corresponding input
Current potential is higher than the full scale of the analog/digital converter, the controller enable alarming device.
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| CN201310453561.2A CN104515902B (en) | 2013-09-29 | 2013-09-29 | Universal meter with high voltage alarm function |
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| CN107402325B (en) * | 2016-05-19 | 2020-01-24 | 錞镱科技股份有限公司 | Electric meter device with light flashing function |
| TWI640777B (en) * | 2017-08-04 | 2018-11-11 | 錞鐿科技股份有限公司 | Electric meter apparatus with light-blinking function |
| CN108828285A (en) * | 2018-08-22 | 2018-11-16 | 深圳市迈斯泰克电子有限公司 | Automatic alarm device and multimeter |
| CN111426864A (en) * | 2020-04-18 | 2020-07-17 | 无锡意美浩科技有限公司 | Universal meter with high-voltage warning function |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5202682A (en) * | 1989-07-13 | 1993-04-13 | Curtis Instruments, Inc. | Data encodement and reading method and apparatus |
| CN2280913Y (en) * | 1996-10-10 | 1998-05-06 | 珠海中胜科技有限公司 | Digital Universal meter with speech prompting alarming function |
| CN2840056Y (en) * | 2005-11-21 | 2006-11-22 | 郭文信 | The multimeter alarm protecting apparatus |
| CN201133916Y (en) * | 2007-01-30 | 2008-10-15 | 王悦 | Multimeter provided with alarming function data collection card |
| CN101650380B (en) * | 2008-08-15 | 2012-11-28 | 承永资讯科技股份有限公司 | Intelligent measuring device automatically selecting measuring functions |
| CN101846698B (en) * | 2009-03-26 | 2012-01-18 | 周筠杰 | Topology structure and method used for multi-function measurement |
| CN201555921U (en) * | 2009-11-09 | 2010-08-18 | 金成实 | Alarm device for testing circuit on-off of digital multimeter |
| CN202421268U (en) * | 2011-11-25 | 2012-09-05 | 漳州市东方智能仪表有限公司 | Overload indication and alarm circuit for digital multimeter |
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