Project 3: H-bridge #

Build an H-bridge motor controller

The third project is to build a motor controller to meet the following requirements:

• It consists of a PCB with connectors for a motor, plus power and control lines.
• It also accepts power from a 2.1 x 5.5 mm plug from a 12 V wall adapter.
• It has a power LED that lights up when motor power is available.
• It can make a DC motor spin in both directions.
• The motor current traces can handle 12 V and 5 A continuously without melting (see notes on PCB ampacity)
• It can be controlled by logic signals from a KB2040.

Here is a graphical version of those first two bullet points about connectors.

Due date for prototype: Monday, October 21, 11:59 PM

To get started building your prototype H-bridge, review the Low Power/high power and the H-bridge(http://andnowforelectronics.com/notes/h-bridges/) pages, including their mini-lecture videos on BJT and MOSFET transistors. After that, if you’re stuck, consult the H-bridge testing demo video. Note that this video is not intended to give you step-by-step building or testing instructions, but rather to give you a feel for the kind of approach you might take to building and testing this circuit. If your H-bridge prototype isn’t working by the deadline for this prototype, don’t worry! Just submit to Canvas a photo of what you have, working or not.

Due date for functional breadboard H-bridge and PCB submission: Monday, October 28, 11:59 PM

When your PCB design is ready, you should submit it to the fabricator, OSH Park. It will cost you around $10. (If this cost is a hardship, please let Kristen or Brandon know, and we will cover the cost by ordering it for you, no questions asked.) After you submit it, take a screenshot of your order confirmation and upload it to the Project 3 PCB assignment on Canvas (proof that you submitted your project on time). Also, take a screenshot of your PCB design in KiCad and upload that as well (it would be a good idea to save this screenshot for your portfolio).

For this final submission to Canvas, you will also need to submit evidence that your H-bridge circuit is functional. So, once you do get your breadboard H-bridge working, take a video that shows it making the motor spin in both directions, controlled by a KB2040. You’ll need that video for your P3 final Canvas submission.

Project 2: Simple game #

Build a simple game

The next project is to use the basic electrical components we’ve covered in class with some mechanical fabrication to make a game that is at least mildly entertaining. The point here is NOT making the best game ever, but to set some goals for testing out your electromechanical skills. For your circuit for this project, use your breadboard. No PCBs needed.

This is a solo project, but we’ll be brainstorming in groups.

You should bring your game to class on Wednesday, October 9th to share with your brainstorming group.

Due date (for game documentation submission): Wednesday, October 9th, 11:59PM

To keep things simple, there are a few required constraints. Your game should:

• Use the DC gearmotor in your kit
• Use at least one transistor
• Require user interaction of some sort (e.g., pushing a button, pressing a key, interacting with a physical component)
• Fit inside a cube 20 cm on a side
• Be fabricated without 3D printing, except for a motor hub if needed (talk to an instructor if you have a particular reason you need to violate this constraint.)

The point of the constraints is to keep your game simple enough that you can complete it in 1.5 weeks.

In addition to planning to meet these constraints, you should also pick one learning goal for yourself for this project. Open-ended projects offer you an opportunity to bend the curriculum into the direction of your interests or to explore a potential new area of interest.

Here are some example learning goals:

• Get more comfortable with cordless drills and at least one other hand tool.
• Test my system to failure, then rebuild it stronger.
• Use only recycled/found materials.
• Complete my project 24 hours early.
• Model, predict and subsequently measure at least one mechanical property of my project.
• Use the laser cutter (which I have never used before).
• Make at least one part out of steel.
• Turn a part on a lathe at Bray.
• Spend at least 1/3 of my effort on the aesthetics of the project.

Project 1: Power supply #

Build a breadboard power supply

The first project is to build a power supply that meets the following requirements:

• It consists of a PCB that plugs directly into a breadboard.
• It accepts power from a 2.1 x 5.5 mm plug from a 12 V wall adapter.
• It emits 12 V, 5 V, and 3.3 V (at the same time).

Due date (for Printed Circuit Board submission): Friday, September 27, 6:00PM

When your design is ready, you should submit it to the fabricator, OSH Park. It will cost you around $10. After you submit it, take a screenshot of your order confirmation and upload it to the Project 1 PCB assignment on Canvas. That will serve as proof that you submitted your project on time. If this cost is a hardship, please email your KiCad files to Brandon or Kristen, and we will order it for you.

More details for Project 1 #

First of all, we’re not trying to build anything revolutionary in this project. None of you have ever made a PCB before, so the point is to make something fairly simple to get comfortable with the process. If you search Amazon for “breadboard power supply”, you’ll see that you can buy various versions of things like this, though none with a 12 V passthrough, so far as we’re aware.

Here’s what a typical one of these things looks like.

The image below shows the mechanical constraints for the PCB. You can make a board of whatever dimensions you want, but it needs to plug into the breadboard, so you probably want to make sure that the pins line up with the holes in the breadboard, as shown below. You can get by with 4 pins, but 8 will make the board stay in place a little more securely. Regardless of how many pins you use, make sure that each rail has only matching pins, i. e. don’t accidentally connect 5 V to GND.

The dimension between the outer pins is estimated at 1.9 inches. It would be a really good idea to verify that dimension on your breadboard. Sometimes the breadboards are a little wider or narrower.

You can rely on the rest of the dimensions being quite accurate.

In your project kit, you’ll find all the components you’ll need to build a prototype of your power supply on a breadboard. You build the prototype and make sure that you’ve got the wiring right. Then, make the PCB with the same connections. Finally, when your PCB arrives in the mail, you can reuse the prototype components on your PCB.

Important note: the pins on the 5V and 3.3V regulators are not in the same order!

Check the datasheets for the components to see which pin is the input pin, which is the output pin, and which should connect to ground.

If you feel like you understand this project pretty well, or if you’ve made a basic circuitboard before, you could try adding additional features. Look at the open source Ant breadboard power supply for inspiration. The schematics are available if you’re curious about the details.

P1 prototype: what you should do before class #5 (before Wed., 9/18) #

1. Read and try to make sense of the website notes on voltage regulation. Pay special attention to the circuit diagram showing the L7805C voltage regulator.
2. Try your best to make a breadboard circuit so that 12 V goes into your circuit and 5 V and 3.3 V come out. To get started, see the schematic on the Voltage Regulators web page. You’ll need to use your 5V and 3.3V voltage regulator components.
3. Install Kicad, version 7.0.11 for the most bug-free experience.
4. Watch Brandon and Kristen’s Kicad demo videos
5. Read as much of chapter 2 from the Practical Electronics textbook as you can.

Project 0: Motor hub #

Create a secure motor attachment

Later this semester, Projects 2 and 4 will require using a motor to actuate some part of an interactive game, and Projects 5 and 6 will involve motor-driven wheels. So in Project 0, you’ll building some knowledge about how to attach a part securely to a motor.

Your task in Project 0 is to design and build a motor hub that meets the following requirements:

• It fits on and attaches to your DC motor shaft
  

• It includes a 3 mm hole located 15 mm from the central axis of your DC motor shaft (you’ll insert a paper clip with a weighted string into this hole)
  

• It stays attached securely enough to handle the amount of torque (load applied to hub) that stalls the motor when it is operating at 12 V
  

Your motor hub can be shaped like a spool, lever arm, or anything; the details are up to you.

Submit to Canvas (1) a photo of your motor hub and (2) a brief video (max 90 seconds) demonstrating that your motor hub meets the requirements above.

Bring your hub to lab on your designated due date. We hope to compile everyone’s results into a histogram showing the range of torques applied before the hubs either (a) slip on their motor shaft or (b) successfully stall the motor.

Due dates are staggered for Project 0 to spread out the demand on fabrication tools at Nolop and Bray. Your hub is due at the start of lab time on the date listed for your weekly lab day.

Prior Student Examples