Socially Useful Productive Work. A Talking Weighing Scale for the Visually Impaired!

 Making something which is socially useful is always desirable. In my ecosystem, I don't care if I can have a car navigate the roads autonomously, using machine learning. What I care about is a weighing scale that can speak out the weight using a suitable hardware and software. Here is a project we did for helping the visually impaired students pursue science in a meaningful way. Hopefully, it will be adopted by NCERT and scaled for widespread use.

 

Electronics Design Workshop - A Hands-on Course

 This semester (January to May 2022), I am teaching a course titled 'Electronics Design Workshop' to 4th semester students of ECE at NSUT. Incidentally, I had designed the syllabus for this course 2 years ago. Although it was offered for the first time last year, I did not have an opportunity to teach it. Now, I do.

The weekly schedule consists of 2 hours of lectures and 4 hours of laboratory session. Although, while the online classes are on, we do not have the luxury of face to face laboratory experience. 

Here is the syllabus:

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Learning Objectives:

1. To be able to visualize a system/product in terms of hardware and software building blocks using a project based learning approach.
2. Learn useful mechanical and electronic fabrication processes.
3. Learn necessary skills to build useful and standalone system/project with enclosures
4. Learn necessary skills to create print and electronic documentation for the system/project
5. Build, test and document a useful power supply before the mid term.
6. Build, test and document a useful project/system.
7. Learn various debugging tools and techniques.

Unit 1: Electronic component familiarization, Understanding electronic system design flow - visualization of system requirements, time planning using Gantt chart, schematic design and PCB layout, circuit fabrication, soldering and testing, heat sink and cooling for critical components, system wiring, building system enclosure, system testing and debugging, documentation. Documentation using Google docs, Overleaf. Documentation from firmware - Doxygen. Version control tools for documentation as well as firmware release management - GIT and GitHub. Familiarization and use of basic measurement instruments - DSO including various triggering modes, 1X and 10X probes, DMM (including CAT I, CAT II, CAT III, and CAT IV type of DMMs), LCR bridge, Signal and function generator. Logic analyzer or MSO. Bench power supply (with 4-wire output)

 Unit 2: Circuit prototyping using (a) breadboard, (b) Zero PCB (c) ‘Manhattan’ style and (d) custom PCB. Schematic design and PCB layout using EagleCAD. Gerber creation and 3D visualization for fitting. Single, double and multilayer PCBs. Single and double sided PCB prototype fabrication in the lab. Soldering using soldering iron/station. Soldering using a temperature controlled reflow oven. Automated circuit assembly and soldering using pick and place machines.

Unit 3: Electronic circuit building blocks including common sensors.  Arduino programming and use. Getting acquainted with the Arduino IDE and Basic Sketch structure. Digital Input and output. Measuring time and events. PWM. Serial communication. Analog input. Interrupts programming. 

Unit 4: Power sources and power supply regulator design. Linear and switching power supply. Transformerless power supply. Zener regulator, op-amp based regulator. 723 IC regulator. 3-terminal IC regulators. LDO and micropower regulators. Buck, Boost and Buck-boost switching regulators. Short circuit and over-voltage protection. Wireless power supply. USB-PD. Battery types and characteristics. Battery charging for lead-acid and lithium type batteries. 

Unit 5: Mechanical fabrication processes - 3-axis CNC, 3D printing, mini lathe, drilling, Laser cutting, Laser engraving etc.. 3D printing technology - FDM, SLS and SLA. 3-axis CNC operation. 2D file designing for drilling, cutting,  milling, Laser Cutting and engraving using Flatcam, Inkspace, OpenBSP. 3D file designing using Sketchup, FreeCAD, Prusa Slicer.

 

Suggested Reading:

1. The Art of Electronics. 3rd edition. Paul Horowitz and Winfield Hill. Cambridge University Press. ISBN: 9780521809269 
2. Practical Electronics for Inventors. 4th edition. Paul Sherz and Simon Monk. McGraw Hill. ISBN-13: 978-1259587542 
3. Encyclopedia of Electronic Components (Volume 1, 2 and 3). Charles Platt. Shroff Publishers. ISBN-13: 978-9352131945, 978-9352131952, 978-9352133703
4. Building Scientific Apparatus. 4th edition. John H. Moore, Christopher C. Davis, Michael A. Coplan and Sandra C. Greer. Cambridge University Press. ISBN-13: 978-0521878586
5. Programming Arduino: Getting Started With Sketches. 2nd edition. Simon Monk. McGraw Hill. ISBN-13: 978-1259641633
6. Debugging. David J. Agans. Amacom. ISBN: 0814474578
7. Make Your Own PCBs with EAGLE: From Schematic Designs to Finished Boards. Simon Monk and Duncan Amos. McGraw Hill Education. ISBN-13 : 978-1260019193.
8. Pro GIT. 2nd edition. Scott Chacon and Ben Straub. Apress. ISBN-13 : 978-1484200773

Laboratory Activities:

Basically, build a stand alone mini-project using Arduino (or any other microcontroller of your choice), some sensors, displays etc. The mini project should have its own power supply or battery power source. The mini-project should be properly enclosed in lab designed and fabricated enclosure which could be 3D printed or made using CNC machining. The mini-project would have a mandatory documentation report.

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For majority of students who join ECE these days, it's not their first choice. If they could, they would have liked to join some CS course. However, I want to assure them that (a) it's all very much crowded in the CS stream (b) there is no dearth of programming opportunities in ECE subjects (c) at the end of the day,  a computer program needs real hardware to run, even if it's in the cloud. YOU can be that engineer who will build that piece of hardware! 

What do I expect you to build? Well, there are a kazillion things you could build. Here is a sample example. It's an AVR microcontroller based circuit, with it's very own custom designed and 3D printed enclosure. It works in two modes - in one of the modes, it displays the ambient temperature on the single seven segment display (by serially printing the three digit temperature in degrees Celsius) and in the other mode, it generates a random number between 0 and F. In the first mode, it can also be used to generate Morse code by pressing the switch or attaching and pressing Morse key to the Aux connector. You will hear the sound of the Morse code on the buzzer that you can see towards the top of the gadget, next to the red seven segment display.

The black blob next to the Aux connector is the temperature sensor (LM35). If you don't see any microcontroller, don't be alarmed. It's on the other side of the PCB, it's a SMD component - Tiny44. The power to the system is from a USB charger or USB power bank, you see that blue cable?

I am very excited to start the classes from tomorrow. Although, I wish we would get over with this third wave quickly and back to normal, face to face classes, so that my students can get real hands-on experience of building useful electronic circuits and systems.