Cattle and horse experiments in the industrial training center
1. Purpose of the experiment:
1) Know the three-terminal electronic switch circuit composed of triode and MOS tube; know the relay and photoelectric isolation method of signal isolation.
2) Know the Schmitt trigger and master a waveform transformation method.
3) Implement a pulse waveform generator.
2. Experimental resources
HBE hardware basic circuit experiment box, oscilloscope, multimeter
Optocoupler isolated MOS tube switch module, NE555 chip
- Experimental task
- Know the triode or MOS tube to form a three-terminal electronic switch circuit; know the relay and photoelectric isolation method of signal isolation.
Module Features:
1. With optocoupler isolation, the control signal is isolated from the power supply of the controlled equipment, which greatly improves the anti-interference.
2. Compatible with MCU and Arduino light control board, 3V or 5V signal
3. High level start, low level stop, PWM speed regulation
4. Widely used to control the start and stop of motors, solenoid valves and other tributary equipment
5. Various specifications of MOS tubes are available for selection, for example: FR120N: 100V 9.4A
6. The signal input side can solder terminals or pins by itself, compatible with breadboards
7. The output can be soldered to the terminal or directly to the wire
8. The module size is 23mm X 16mm. There are two 2mm diameter screw holes with a spacing of 8mm.
Recognize the picture and measure the function of [optocoupler isolation NMOS switch circuit]:
In the figure, the left signal terminal uses DC5V switching signal, and the right load terminal uses 5~30V DC power supply (such as DC5V or 12V)
【*】Using an LED light plus a suitable current limiting resistor as the load, use a dual-channel oscilloscope to observe and record the waveforms of the optocoupler pin 3 and load terminal H2 pin 2 when the IO signal is switched on and off.
[*] Input the 0-5VTTL square wave signal source at the signal terminal, adjust the square wave frequency from small to large, and use a dual-channel oscilloscope to observe whether the input and output signals can be synchronized to estimate the switching speed of the module circuit.
【*】Analyze the optocoupler and NMOS functions by combining the above waveforms and level peak-to-peak values.
- Experimental process and records
1 Know the triode or MOS tube to form a three-terminal electronic switch circuit; know the relay and photoelectric isolation method of signal isolation.
Experimental steps:
1. With the LED light plus a suitable current-limiting resistor as the load, use a dual-channel oscilloscope to observe and record the waveforms of the optocoupler pin 3 and load terminal H2 pin 2 when the IO signal is switched on and off.
2. Input the 0-5VTTL square wave signal source at the signal terminal, adjust the square wave frequency from small to large, and use a dual-channel oscilloscope to observe whether the input and output signals can be synchronized to estimate the switching speed of the module circuit.
3. Combining the above waveforms and peak-to-peak levels to analyze the optocoupler and NMOS functions.
Experimental results:
Result analysis:
As shown in the figure, the output port waveform changes with the input waveform, but there is a certain phase difference. When the input frequency increases to a certain level (110MHz), the input terminal will no longer be able to receive signals.
Experience summary
1. Learning knowledge points: Learned and mastered the basic knowledge and basic principles of electronic switches and signal isolation , recognized and learned the basic functions of optocoupler-isolated MOS tube switch modules, and carried out practical operations. Learned some anti-shake methods of circuit switches.
2. Scalability: multiple measurements should be made to reduce errors
3. Humanities: Realized the importance of team order. In the face of limited experimental equipment and a large demand in a short period of time, good communication can reduce a lot of time costs. At the same time, when facing the fine operation of multi-stage multi-person cooperation, it is very necessary to maintain a high degree of patience and efficient communication.
4. Memory: When the knowledge is not mastered, timely consultation and observation can greatly establish a preliminary cognition and promote the mastery of knowledge. At the same time, in the face of various technologies, getting started directly and learning in operation may be the fastest way to learn