CN205787001U - Multi-functional transistor checker - Google Patents

Abstract

The utility model relates to a multifunctional transistor tester. The tester is provided with a transistor measurement platform, a transistor measurement port, a liquid crystal screen, a switch, a current adjustment knob, a voltage adjustment knob, a frequency adjustment knob, measurement storage and selection buttons, and an oscilloscope output. Port, signal communication port, SD card port and function knob, the tester has two microprocessor main chips, D/A conversion and control circuit, current source circuit, voltage source circuit, measurement circuit, drive circuit, liquid crystal display circuit , SD card storage circuit and digital control frequency source circuit. The tester adopts a high-performance microprocessor, which can realize the functions of accurate measurement and display of various parameters of transistor characteristics, and at the same time, it can carry out signal communication and storage of measurement information, and is easy to expand. It is suitable for measurement and teaching experiments of electronic circuit, physics and other courses in schools at all levels.

Description

Multifunctional Transistor Tester

technical field

The utility model relates to a multifunctional transistor tester, which belongs to the field of electronic technology application and experimental application.

Background technique

Transistor testing is to use tools to measure and display transistor parameters and input and output characteristic curves. At present, analog transistor graph instruments are widely used in laboratories, which have high cost, large volume, large power consumption, and cannot store data for testing Compare and analyze. Although some foreign high-precision, digital transistor testers are gradually being developed to replace the analog transistor graphs, they are all expensive and have complicated functions. The design of the utility model is a transistor tester with low power consumption and high performance based on the MSP430F479 microprocessor.

Existing measuring instruments generally can only measure the output characteristics of transistors. However, the various components of the utility model are mostly realized by integrated digital chips, which are relatively easy to manufacture and low in cost, and are easy to use. In addition to measuring and observing the output characteristic curve of the transistor, the frequency characteristic of the transistor can also be measured, and it has a convenient liquid crystal Display and a variety of output and storage functions, the input and output characteristic measurement and frequency characteristic measurement parts of the system are each controlled by a microprocessor. It can also cooperate with ordinary oscilloscopes and computers that are common to people. This tester can basically meet the requirements of general researchers.

Utility model content

Aiming at the deficiencies of existing experiments and testing instruments, the multifunctional transistor tester designed by the utility model combines microprocessors, liquid crystal screens, SD card storage, current sources, voltage sources, frequency sources and other circuits, and has multiple signal The output method and operation control method can complete the measurement, display, analysis, storage and other functions of various characteristic parameters of the transistor, and at the same time, it is small in size, high in precision and low in power consumption.

This multifunctional transistor tester is equipped with transistor measurement platform, transistor measurement port, LCD screen, switch, current adjustment knob, voltage adjustment knob, frequency adjustment knob, measurement storage and selection buttons, oscilloscope output port, signal communication port, SD card Port and function knob, the tester has two microprocessor main chips, D/A conversion and control circuit, current source circuit, voltage source circuit, measurement circuit, drive circuit, liquid crystal display circuit, SD card storage circuit and numerical control frequency source circuit.

The microprocessor main chip 1, D/A conversion and control circuit, current source and voltage source circuit, the transistor under test, and the measurement circuit in the tester are connected in sequence, and the measurement circuit is connected to the microprocessor main chip 1; SD The card storage circuit is connected with the microprocessor main chip 1, the microprocessor main chip 2, the numerical control frequency source circuit, and the transistor under test are connected sequentially; and each microprocessor main chip, driving circuit, and liquid crystal display circuit are connected sequentially.

The two microprocessor main chips used in this test ceremony are MSP430F479 produced by TI. It is an ultra-low-power microprocessor based on a true orthogonal 16-bit RISCCPU core, with 16 single-cycle fully addressable 16-bit registers, 3 different clock signals, 6 operating modes, The power consumption current is very small, and it can be placed in power-saving mode, which can be woken up by interrupt to reduce power consumption as much as possible. MSP430F479 has powerful computing performance, including precision hardware multiplier, 60KB FLASH, 2KB RAM, 12-bit high-precision A/D converter, high-precision comparator and other common resources on-chip. The debugging of the system code can be completed through the on-chip JTAG debugging interface, and the development environment is convenient and efficient.

The liquid crystal drive and display circuit of this tester adopts a 128×64 liquid crystal display with a low voltage, low power consumption, a Chinese character library, and a ST7920 controller. It has multiple interface modes of 4/8-bit parallel, 2-wire or 3-wire serial. Its module interface mode is flexible, and the operation instructions are simple and convenient. It can complete graphic display and display 8×4 lines of 16×16 dot matrix. Chinese characters can constitute a complete human-computer interaction graphic interface. At the same time, the measurement storage and selection buttons of the tester adopt membrane buttons.

Description of drawings

Figure 1 is the appearance of the tester, where 1 is the transistor measurement platform, 2 is the transistor measurement port, 3 is the LCD screen, 4 is the switch, 5 is the current adjustment knob, 6 is the voltage adjustment knob, 7 is the frequency adjustment knob, 8 are measurement storage and selection buttons, 9 is an oscilloscope output port, 10 is a signal communication port, 11 is an SD card port, and 12 is a function knob.

Figure 2 is a schematic diagram of the system circuit.

Figure 3 is a circuit diagram of the voltage acquisition.

Figure 4 is a circuit diagram of the SD card interface.

detailed description

In conjunction with the accompanying drawings, the work and circuit conditions of the multifunctional transistor tester will be described in detail below.

In the actual measurement, the tester needs to send the voltage signals of the three electrodes of the transistor to the A/D converter. The transistors with pin arrangement are used for measurement. The measurement circuit of the transistor under test adopts the common emitter connection form. In the voltage signal acquisition circuit, DA-OUT is output by 3 pieces of D/A converters, and then through the proportional amplification of the pre-stage op amp and The analog voltage signal output by the post-stage power amplifier controls the voltage or current signal of the base, collector and emitter of the transistor respectively, and the test conditions are established by the changing voltage or current signal provided by the base and collector. The voltage signals obtained from the three electrodes are sent to the A/D converter for analog/digital conversion through the voltage follower composed of LM358 operational amplifier.

The D/A converter of the utility model adopts a 32-channel high-speed chip MAX5631 produced by MAXIM Company of the United States, which contains a 16-bit DAC, a timing controller with an internal clock, an on-chip RAM and 32 channels of sampling and holding amplifier. The DAC circuit is composed of two parts. MAX5631 can provide a maximum resolution of 200μV and high-precision conversion of 0.015% FSR. Its output voltage range is -4.5V to 9.2V, and it has the characteristics of operating temperature range and flexible serial interface, and does not need to configure external gain and offset. Set circuit, suitable for occasions dealing with a large amount of analog data output.

In the measurement, the output characteristic of the transistor is the relationship between the voltage Uce between the collector and the emitter of the transistor and the collector current at a certain base current. When the tester is in use, combine the current adjustment knob and the voltage adjustment knob, and each current corresponds to an output characteristic curve. By displaying the curves corresponding to multiple currents at the same time, a group of output characteristic curves can be obtained. The current source is connected to the base of the transistor, and the voltage source is connected to the emitter and collector terminals. The current source generates a gradually increasing base current under the control of the main microprocessor chip 1 , and the corresponding voltage source can also generate a gradually increasing collector junction voltage Uce. When measuring the input characteristics of the transistor, Uce should be fixed to a certain value first, and then the base current should be gradually increased from 0.

When measuring the output frequency characteristics of the transistor, the numerical control frequency source generates an AC signal with a gradually increasing frequency under the control of the microprocessor chip 2. The AC signal is connected to the supplementary measurement transistor, and combined with the function knob, the signal can be connected to the oscilloscope channel. Features such as AC magnification and frequency phase can be measured by zooming in on the oscilloscope.

The numerical control frequency source of the utility model adopts DDS chip AD9852, AD9852 can produce highly stable frequency, phase, amplitude variable sine and cosine output, AD9852 provides a frequency resolution of 48 bits, and the phase is quantized to 14 bits, ensuring extremely High frequency resolution and phase resolution, with wide bandwidth, short frequency conversion time, high frequency resolution, continuous output phase and so on.

The SD card of the present utility model works in SPI mode, and its SPI interface utilizes CS, SCLK, DATA IN, DATAOUT of the SD card to communicate with MSP430F479, wherein DATA IN and DATA OUT are the input and output signal lines of data, and CS is the SD chip The chip select signal line, during the entire SPI operation, CS must remain active low, and SCLK is the clock signal provided by the external controller.

The signal communication between the utility model and the PC uses the RS232 communication protocol for data transmission. In actual use, combined with the function selection knob, current, voltage and frequency adjustment knob, multiple transistors under different currents, voltages and frequencies can be realized. A characteristic measurement and output. At the same time, combined with the function selection knob and RS232 signal communication port, it can better complete the display and analysis of transistor characteristics.

The tester adopts a high-performance microprocessor, which can realize the functions of accurate measurement and display of various parameters of transistor characteristics, and at the same time, it can carry out signal communication and storage of measurement information, and is easy to expand. It is suitable for measurement and teaching experiments of electronic circuit, physics and other courses in schools at all levels.

Claims (3)

1. A multifunctional transistor tester, characterized in that: the tester is provided with a transistor measurement platform (1), a transistor measurement port (2), a liquid crystal screen (3), a switch (4), and a current adjustment knob (5) , voltage adjustment knob (6), frequency adjustment knob (7), measurement storage and selection buttons (8), oscilloscope output port (9), signal communication port (10), SD card port (11) and function knob (12) ; There are two microprocessor main chips in the tester, D/A conversion and control circuit, current source circuit, voltage source circuit, measurement circuit, drive circuit, liquid crystal display circuit, SD card storage circuit and digital frequency source circuit; Microprocessor main chip 1, D/A conversion and control circuit, current source and voltage source circuit, measured transistor, and measurement circuit are connected sequentially, and the measurement circuit is connected to microprocessor main chip 1; SD card storage circuit and microcomputer The processor main chip 1 is connected, the microprocessor main chip 2, the numerical control frequency source circuit, and the transistor under test are connected sequentially; and each microprocessor main chip, driving circuit, and liquid crystal display circuit are connected sequentially. 2. The multifunctional transistor tester according to claim 1 is characterized in that: the two microprocessor main chips adopted in its tester are MSP430F479 produced by TI Company. 3. multifunctional transistor tester according to claim 1, is characterized in that: its drive and liquid crystal display circuit adopt low voltage, low power consumption band Chinese font library, adopt the 128 * 64 liquid crystal display of ST7920 controller; Its measurement The storage and selection keys adopt membrane keys.