CN205809184U - Simple pulse polarity tester - Google Patents

Abstract

The utility model provides a simple pulse polarity tester, which includes a power supply circuit, a high and low level judging circuit, a diode network circuit and a display circuit, and is characterized in that the high and low level judging circuit is connected to the diode network circuit, and the diode network circuit is connected to the display The circuit, the high and low level judging circuit, the diode network circuit and the display circuit are respectively connected with the power supply circuit; the high and low level judging circuit includes an integrated chip DM7400N and a triode; the display circuit includes a digital tube. The utility model not only has simple structure and low production cost, but also has reliable performance, convenient use and wide application range.

Description

Simple Pulse Polarity Tester

technical field

The utility model relates to a pulse polarity tester, in particular to a simple pulse polarity tester.

Background technique

In digital circuit scientific research experiments or electronic maintenance and other occasions, pulse polarity testers are often required. Most of the polarity pulse testing devices on the market are logic test pens. Most of these logic test pens have complex circuit structures, and the high and low levels are displayed by the color of the LED light. The disadvantages of these logic test pens are that they are less intuitive and more expensive, the damaged circuit devices are not easy to repair, and the service life is not long, which brings a lot of inconvenience to users.

Contents of the invention

The purpose of this utility model is to realize the determination of the high and low level state of the circuit by means of digital logic circuit control. According to different needs, it can be measured at any test point of the circuit or system, and the circuit can be completed without affecting the test circuit. High and low level logic state judgment.

The utility model is realized in this way, it comprises a power supply circuit, a high and low level judging circuit, a diode network circuit and a display circuit, and is characterized in that the high and low level judging circuit is connected to the diode network circuit, the diode network circuit is connected to the display circuit, and the high and low level judging circuit Circuit, diode network circuit and display circuit are respectively connected to the power supply circuit; the high and low level judging circuit includes an integrated chip DM7400N and a triode, and the integrated chip DM7400N is used to realize the judgment of high and low levels, and different signal outputs are provided as the triode according to the judgment results. The trigger control signal; the display circuit includes digital tubes for displaying test results.

The utility model also includes a probe connected with the high and low level judging circuit, the probe is used to contact the test point in the circuit to be tested, and transmits the pulse signal of the test point to the high and low level judging circuit.

The power source of the power circuit comes from the circuit under test or other power module accessories, and provides the positive 5V voltage required by the normal operation of the utility model.

The diode network circuit uses the unidirectional conductivity of the diode to control the display of different fields of the digital tube.

Preferably, the power circuit includes a clamp for a power cord, a clamp for a power ground wire, and a power switch, which are convenient for connecting the positive and negative poles of the power supply of the circuit under test or the positive and negative poles of other power accessories.

Preferably, the display circuit further includes an LED light for indicating the power-on state.

The beneficial effects of the utility model are: the simple and reliable hardware circuit is adopted, not only the performance is stable, but also the production cost is low; the universal integrated chip DM7400N design is adopted, the chip is replaceable, easy to maintain, and the product has good versatility; Simple panel design, easy to operate, and set the power on display function.

Description of drawings

Fig. 1 is a schematic block diagram of the utility model.

Fig. 2 is a circuit diagram of the utility model.

Fig. 3 is a schematic diagram of the external design of the utility model.

Fig. 4 is the pin diagram of the used integrated chip DM7400N of the utility model.

In the figure, 1. Probe, 2. Power circuit, 3. High and low level judgment circuit, 4. Diode network circuit, 5. Display circuit, 21. Power cord clamp, 22. Power ground wire clamp, 23. Power switch, 51. Nixie tube, 52. LED light.

detailed description

As shown in Fig. 1, Fig. 2 and Fig. 3, the utility model is realized in this way, and it comprises probe 1, power supply circuit 2, high and low level judging circuit 3, diode network circuit 4 and display circuit 5, wherein power supply circuit 2 It includes a power cord clamp 21, a power ground wire clamp 22 and a power switch 23; the high and low level judgment circuit 3 includes an integrated chip DM7400N and a triode 9013; the display circuit 5 includes a digital tube 51 and an LED light 52. The power terminal and ground terminal of the integrated chip DM7400N are respectively connected to the power circuit 2 and the ground (not shown in Figure 2), and the two input terminals of one of the NAND gates of the integrated chip DM7400N are connected to the probe 1. The NAND gate The output terminal is connected to the transistor 9013. The specific connection relationship of each component is shown in Figure 2.

When it is necessary to know the pulse polarity of a certain circuit test point, first connect the power cord clamp 21 and the power ground wire clamp 22 of the power supply circuit 2 of the present utility model to the positive and negative terminals of the circuit under test or other power module accessories respectively, Turn off the power switch 23, when the power is turned on, the LED light 52 is lighted, indicating that the circuit starts to work. Then touch the probe 1 to the test point of the circuit. If a positive pulse comes, the nixie tube 51 will be lighted up through the resistance R ₁ , R ₂ , R ₈ branch and the resistance diode R ₆ D ₄ , R ₇ D ₅ branch. Sections b, c, e, f and g, at this time, because the high level becomes low level after passing through the chip DM7400N, the triode 9013 is cut off, the output is low level, the diodes D ₁ , D ₂ and D ₃ are cut off, and the digital tube 51 The d section of the digital tube 51 will not be lit, and the digital tube 51 displays "H" to indicate a high level; when a negative pulse is detected, the low level becomes a high level after passing through the integrated chip DM7400N, and the output of the triode 9013 is high. level, diodes D ₁ , D ₂ and D ₃ are turned on, lighting segments d, e and f of digital tube 51, while other branches are blocked at this time, segments b, c and g of digital tube 51 will not be When it is on, the nixie tube 51 displays "L" to indicate that the low level is read. Section a of the nixie tube 51 is not connected to the circuit, no matter how the polarity of the circuit test point is, it will not be lit.

It can be seen from Figure 3 that this design scheme is very convenient to use. There are three terminals for external wiring, which are respectively connected to the power cord clamp 21, the power ground wire clamp 22 and the probe 1, the power cord clamp 21, the power supply The ground clamp 22 is used to connect the positive and negative poles of the power supply of the circuit under test or the positive and negative poles of other power supply accessories. The probe 1 can be easily connected to a test point in the circuit under test. The simple design provides a power switch 23 with an LED light 52 as a power indicator. Compared with other instruments (such as a multimeter), it has the advantage of higher cost performance.

As shown in Figure 4, because the integrated chip DM7400N contains four independent unit NAND gate circuits, and each unit NAND gate circuit has two input terminals, only two input terminals of one of the NAND gate circuits are used in this design. Connect probe 1 together to form a NOT gate circuit. When the NAND gate in use is damaged, the other three NAND gates can be replaced, and it is generally unnecessary to replace the integrated chip DM7400N.

Claims (5)

1. A simple pulse polarity tester comprising a power supply circuit, a high and low level judging circuit, a diode network circuit and a display circuit, characterized in that: the high and low level judging circuit is connected to the diode network circuit, and the diode network circuit is connected to the display circuit, The high and low level judging circuit, the diode network circuit and the display circuit are respectively connected with the power supply circuit; the high and low level judging circuit includes an integrated chip DM7400N and a triode; the display circuit includes a digital tube. 2. The simple pulse polarity tester according to claim 1, further comprising a probe connected to the high and low level judging circuit. 3. The simple pulse polarity tester according to claim 1, characterized in that: the power source of the power circuit comes from the circuit under test or other power module accessories. 4. The simple pulse polarity tester according to claim 1, characterized in that: said power circuit includes a power cord clamp, a power ground wire clamp and a power switch. 5. The simple pulse polarity tester according to claim 1, characterized in that: said display circuit further includes an LED light.