CN104122011B - Thermometric instrument checking signal generator - Google Patents

Abstract

A kind of thermometric instrument checking signal generator, it is to utilize digital multimeter transformation to form, its concrete remodeling method is: select four Semi-digital circuit testers with independent on and off switch, utilize the 9V battery in digital multimeter, a 10K fixed resistance is increased in digital multimeter, the adjustable resistance of one 300 Ω, the double-pole multithrow switch of one 3, described fixed resistance, the 9V battery strings of adjustable resistance and digital versatile is unified into loop, the two ends of described adjustable resistance connect COM end and the mV measurement end of digital multimeter respectively, the internal resistance of circuit tester is also in parallel with adjustable resistance simultaneously, described double-pole multithrow switch is connected in parallel on one end of adjustable resistance.Present configuration is simple, novel in design, only digital multimeter need to be changed a little, on the premise of not affecting its original function can conveniently with the circuit tester Replacement value about ten thousand yuan of hundreds of unit and carry in-convenience in use tester, its most alternative resistance box and electron potentiometer.

Description

Thermometric instrument checking signal generator

Technical field

The present invention relates to chemical technology field, be specifically related to a kind of thermometric instrument checking signal generator.

Background technology

In commercial production, particularly in chemical process, Thermal Meter is applied widely.Producing During, instrument can occur various fault, so it is frequently necessary to Thermal Meter particularly temperature Instrument is calibrated.To temperature once, secondary meter calibration and during simulation general we need to carry resistance Case and electron potentiometer or process checking gauge are to common tools such as on-the-spot, circuit testers to be carried. At work, these reference instruments are the most valuable but also are inconvenient to carry.Due to valuable (on the most thousand of Ten thousand or several ten thousand) use at the scene very inconvenient.

Digital multimeter is one of the most standing instrument of instrument attendant, four hundreds of circles of Semi-digital circuit tester The most available.Only digital multimeter need to be changed a little, can be square on the premise of not affecting its original function The most efficiently with the circuit tester Replacement value about ten thousand yuan of hundreds of unit and carry in-convenience in use tester Device.

Summary of the invention

The technical problem to be solved is that providing a kind of constitutes simply, good in economic efficiency temperature Instrument check signal generator.

The technical problem to be solved realizes by the following technical solutions:

A kind of thermometric instrument checking signal generator, it is to utilize digital multimeter transformation to form, and it is concrete Remodeling method is:

Select four Semi-digital circuit testers with independent on and off switch, utilize the 9V battery in digital multimeter, 10K fixed resistance, adjustable resistance of 300 Ω, one 3 double are increased in digital multimeter Cutter multithrow switch, the 9V battery strings of described fixed resistance, adjustable resistance and digital versatile is unified into loop, institute The two ends stating adjustable resistance connect COM end and mV measurement end, the simultaneously internal resistance of circuit tester of digital multimeter respectively Also in parallel with adjustable resistance, described double-pole multithrow switch is connected in parallel on one end of adjustable resistance.

Described fixed resistance is contained in digital multimeter inner chamber space, adjustable resistance, little double-pole multithrow switch Install at digital multimeter lateral opening hole.

The manufacturing firm of digital multimeter also can throw double-pole (3) switch more and be retrofitted in circuit tester itself On rotary switch, so use more convenient.

Using method:

1) double-pole multithrow switch is when 1, can send mV signal: double-pole multithrow switch puts 1, numeral ten thousand With table 200mV shelves, regulation adjustable resistance to digital multimeter mV value reading is the mV value needing to send, number Word circuit tester two test pencil i.e. exports required mV signal；

Double-pole multithrow switch position of double-pole multithrow switch when 1 is: a-b end is connected, and e-f end is connected Logical, remaining disconnects；

2) double-pole multithrow switch is when 3, can use as resistance box: double-pole multithrow switch puts 3, number Word circuit tester is the electricity needing to send with 200 or 2K Ω shelves, regulation adjustable resistance to circuit tester resistance value reading Resistance, circuit tester two test pencil i.e. exports required mV signal；

Double-pole multithrow switch is when 3, and double-pole multithrow switch position is: c-d end is connected, and g-h end is connected Logical, remaining disconnects；

3) double-pole multithrow switch is when 2, and digital multimeter recovers former use function；

Double-pole multithrow switch is when 2, and the position of double-pole multithrow switch K is: b-c end is connected, f-g end Being connected, remaining disconnects.

The invention has the beneficial effects as follows: present configuration is simple, novel in design, only need to be to digital multimeter Change a little, can conveniently replace with the circuit tester of hundreds of unit on the premise of not affecting its original function Cost value about ten thousand yuan and carry in-convenience in use tester, its most alternative resistance box and electricity Electronic potentiometer.

Accompanying drawing explanation

Fig. 1 is the embodiment of the present invention 1 general connection diagram；

Fig. 2 is the embodiment of the present invention 1 double-pole multithrow switch circuit diagram when 1；

Fig. 3 is the embodiment of the present invention 1 double-pole multithrow switch circuit diagram when 3；

Fig. 4 is the embodiment of the present invention 2 general connection diagram；

Fig. 5 is circuit diagram after the embodiment of the present invention 2 digital multimeter power-off.

Detailed description of the invention

For the technological means making the present invention realize, creation characteristic, reach purpose and effect and be readily apparent from Solve, below in conjunction with being specifically illustrating, the present invention is expanded on further.

Embodiment 1

As it is shown in figure 1, a kind of thermometric instrument checking signal generator, its be utilize digital multimeter transformation and Becoming, its concrete remodeling method is:

Select four Semi-digital circuit testers with independent on and off switch, utilize the 9V battery in digital multimeter E, increase in digital multimeter 10K fixed resistance R0, the adjustable resistance RT of 300 Ω, one The 9V battery E of double-pole multithrow switch K, fixed resistance R0, adjustable resistance RT and the digital versatile of 3 is connected into Loop, the two ends of adjustable resistance RT meet COM end (A end) and mV measurement end (B end) of digital multimeter respectively, The internal resistance RB of circuit tester is also in parallel with adjustable resistance RT simultaneously, and double-pole multithrow switch K is connected in parallel on adjustable resistance RT One end.

Fixed resistance R0 is contained in digital multimeter inner chamber space, adjustable resistance RT, little double-pole multithrow switch K Install at digital multimeter lateral opening hole.

The manufacturing firm of digital multimeter also can throw double-pole (3) switch more and be retrofitted in circuit tester itself On rotary switch, so use more convenient.

Using method:

1) double-pole multithrow switch K is when 1, can send mV signal: double-pole multithrow switch K puts 1, numeral Circuit tester 200mV shelves, regulation adjustable resistance RT to digital multimeter mV value reading is the mV needing to send Value, digital multimeter two test pencil i.e. exports required mV signal；

Double-pole multithrow switch K is when 1, and the position of double-pole multithrow switch K is: a-b end is connected, e-f end Being connected, remaining disconnects；

2) double-pole multithrow switch K is when 3, can use as resistance box: double-pole multithrow switch K puts 3, Digital multimeter 200 or 2K Ω shelves, regulation adjustable resistance RT send to circuit tester resistance value reading for needs Resistance value, circuit tester two test pencil i.e. exports required mV signal；

Double-pole multithrow switch K is when 3, and double-pole multithrow switch K position is: c-d end is connected, g-h end phase Connection, remaining disconnects；

3) double-pole multithrow switch K is when 2, and digital multimeter recovers former use function；

Double-pole multithrow switch K is when 2, and the position of double-pole multithrow switch K is: b-c end is connected, f-g end Being connected, remaining disconnects.

Operation principle:

E=9VRO=10KRT=300 Ω

Double-pole multithrow switch K, when 1, opens circuit tester power supply, such as Fig. 2: RO, RT and circuit tester battery E Being connected into loop, RT two ends meet circuit tester COM and mV respectively and measure end simultaneously.

As RT=0 Ω, loop current:

I1=9 ÷ 10000=0.0009 (A)=0.9 (mA)

As RT=300 Ω, loop current:

I2=9 ÷ 10300=0.00087 (A) ≈ 0.87 (mA)

E1=RT × I1=0 × 0.9=0 (mV)

E2=RT × I2=300 × 0.87 ≈ 260 (mV)

By can be calculated: by regulation RT, A, B two ends exportable 0～the potential value of 260mV, its precision Being exactly the precision of circuit tester mV shelves, the precision of general four Semi-digital circuit testers is up to 0.1 to 0.05 grade.(number Word circuit tester internal resistance is on mV output nothing impact).

Double-pole multithrow switch K when 3, circuit such as Fig. 3: (RT be connected in parallel on circuit tester COM and Ω measure end, The internal resistance of circuit tester simultaneously also with RT connecing.)

First open circuit tester on and off switch, put 200 or 2K Ω shelves, regulate RT, make the resistance readings of table for needing Resistance value to be exported, closes circuit tester power supply, and the circuit tester after repacking is exactly adjustable resistor, numeral Circuit tester internal resistance general 20K Ω to hundreds of K Ω, calculates as a example by circuit tester internal resistance 50K Ω:

Circuit tester reading is 50 Ω then A, B two ends resistance:

R=50 × 50000 ÷ (50+50000)=49.95 (Ω)

Relative error is: $\frac{50-49.95}{50}\×100\%=0.1\%$

Circuit tester reading is 150 Ω then A, B two ends resistance:

R=150 × 50000/ (150+50000)=149.55 (Ω)

Relative error is: $\frac{150-149.55}{150}\×100\%=0.3\%$

Circuit tester reading is 300 Ω then A, B two ends resistance:

R=300 × 50000 ÷ (300+50000)=298.21 (Ω)

Relative error is: $\frac{300-298.21}{300}\×100\%=0.60\%$

As selected circuit tester internal resistance larger, precision can be higher.

Circuit tester internal resistance is that 100K Ω is, internal resistance impact is up to 0.3%.

Calculating by 50K Ω, consider further that the resistance grade precision of circuit tester, its available accuracy is higher than 1.0%, output Resistance 0～300 Ω.

Embodiment 2

In order to reach higher precision (four Semi-digital circuit tester resistance grade precision 0.4 to 0.2 grade), can be by figure Carry out shown in 4 reequiping:

The on and off switch of digital multimeter is DPDT K0, and general Zhi Yong mono-tunnel, another road can be used Reequiping, i port connects digital multimeter COM socket, and j port connects digital multimeter circuit board COM end. I.e. digital multimeter circuit board COM end to COM socket is connected and disconnect, be connected on respectively on a, b, with double-pole Double-throw K0 is connected together.

After transformation, operational approach is identical with embodiment 1, operates constant, when after circuit tester power-off, and circuit As it is shown in figure 5, its precision is exactly the precision of circuit tester Ω shelves, the precision of general four Semi-digital circuit testers is 0.2 grade.

By calculating: first measure circuit tester internal resistance, then by 50 Ω or 10 Ω mono-grade, calculate correction value, Precision is improved by revising.

By actually used, substantially meet adjustment temperature secondary meter and in-site modeling temperature primary instrument letter Number requirement, easy to use, respond well.

The ultimate principle of the present invention and principal character and advantages of the present invention have more than been shown and described.One's own profession Skilled person will appreciate that of industry, the present invention is not restricted to the described embodiments, above-described embodiment and explanation The principle that the present invention is simply described described in book, without departing from the spirit and scope of the present invention, The present invention also has various changes and modifications, and these changes and improvements both fall within claimed invention model In enclosing.Claimed scope is defined by appending claims and equivalent thereof.

Claims (2)

1. a thermometric instrument checking signal generator, it is characterised in that: it is to utilize digital multimeter to change Making and form, its concrete remodeling method is:

Select four Semi-digital circuit testers with independent on and off switch, utilize the 9V battery in digital multimeter, 10K fixed resistance, adjustable resistance of 300 Ω, one 3 double are increased in digital multimeter Cutter multithrow switch；

The 9V battery strings of described fixed resistance, adjustable resistance and digital multimeter is unified into loop, described adjustable The two ends of resistance connect the COM end of digital multimeter respectively and mV measures end, the internal resistance of circuit tester simultaneously also with can Adjusting resistor coupled in parallel, described double-pole multithrow switch is connected in parallel on one end of adjustable resistance；

The using method of described thermometric instrument checking signal generator is as follows:

(1) double-pole multithrow switch is when 1, the 9V electricity of fixed resistance, adjustable resistance and digital multimeter Pond is connected into loop, and the two ends of described adjustable resistance connect COM end and the mV measurement end of digital multimeter respectively, Sending mV signal: double-pole multithrow switch puts 1, digital multimeter 200mV shelves, regulation adjustable resistance is extremely Digital multimeter mV value reading is the mV value needing to send, and digital multimeter two test pencil i.e. exports required mV letter Number；

Double-pole multithrow switch position of double-pole multithrow switch when 1 is: a-b end is connected, and e-f end is connected Logical, remaining disconnects；

(2) double-pole multithrow switch is when 3, and the internal resistance of circuit tester is in parallel with adjustable resistance, described adjustable The two ends of resistance connect COM end and the mV measurement end of digital multimeter respectively, use as resistance box: double-pole is many Throw switch puts 3, first opens circuit tester on and off switch, puts 200 or 2K Ω shelves, regulates adjustable resistance, makes The resistance readings of table is the resistance value needing output, closes circuit tester power supply, and the circuit tester after repacking is exactly Adjustable resistor；

Double-pole multithrow switch is when 3, and double-pole multithrow switch position is: c-d end is connected, and g-h end is connected Logical, remaining disconnects；

(3) double-pole multithrow switch is when 2, and digital multimeter recovers former use function；

Double-pole multithrow switch is when 2, and the position of double-pole multithrow switch K is: b-c end is connected, f-g end Being connected, remaining disconnects.

Thermometric instrument checking signal generator the most according to claim 1, it is characterised in that: described Fixed resistance is contained in digital multimeter inner chamber space, and adjustable resistance, double-pole multithrow switch are in digital versatile Table lateral opening hole is installed.