April 9, 2021
April 9, 2021
April 10, 2021
COVID-19 has precluded a large number of undergraduate students from entering the lab and gaining hands-on experience for theoretical concepts taught in online classes. This has affected the conceptual understanding of the topics and degraded student motivation. We developed a Do-It-Yourself (DIY) compose-able virtual hardware board (located in a lab remotely) to enable remote learning for courses such as analog circuit design. The board consists of remotely selectable hardware components such as transistors, logic gates (combinational and sequential), and passive (e.g., resistors and capacitors) components using multiplexers controlled through myDAQ (a commercially available hardware that interfaces with the board). These components can be composed on a breadboard to create the desired circuit (such as common source amplifier with specified gain) remotely by sending commands to the myDAQ by a software interface for virtual experiments. The output of the board can be digitized and sent to the student's PC for visualization. The proposed setup can be time-shared with multiple students and can also be easily replicated. This framework is modular (i.e., other components like an extra breadboard with new designs can be added) and is also useful in the longer-term by allowing the students to personalize their learning.
Board design: The design of the whole system consists of two parts--board and controller. In the board design, we created simple common-source and differential amplifier circuits. In order to help students learn the effect of load and biasing points, two different loads were set up using different loading resistors. Various bias voltages are accomplished by using voltage dividers so that the MOSFETs can work in two different areas of operation. Each of the bias and load settings is user selectable. To switch between various circuit configurations, analog switches are utilized. In addition, the multiplexers are used to decode the digital control signal from the controller to actual signals that control the analog switches. The values of the resistors in the load are set to provide a proper gain and the resistor in the voltage dividers are fine-tuned using potentiometers. The complete circuits are created first and the analog switches are added later. Due to the relatively low on-resistance, the added analog switches have minimal effect on the pre-designed circuit. In the controller design, LabVIEW has been chosen as a programming language and myDAQ has been chosen as a cheap alternative to costly instruments. A user interface has been designed by using this hardware and software to control the circuit and read the resulting output signal through a computer. The functionality of the board has been validated experimentally.
Conclusions: We developed a modular, remote reconfigurable, and reproducible hardware board to help students conduct their experiments remotely. The board has been validated for multiple amplifier circuits.
Xiong, Y., & Porter, S., & Ghosh, S. (2021, April), A Reconfigurable and Modular Hardware for Remote Learning of Analog Circuit Design Paper presented at Middle Atlantic ASEE Section Spring 2021 Conference, Virtual . https://peer.asee.org/36281
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