Projects

Projects #

Project #2: Build an H-bridge motor controller #

The second project is to build a motor controller with the following characteristics:

  • 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.
  • It can be controlled by logic signals from a Feather (but later, not as part of what you submit for P2).

Due date for prototype: Tuesday, October 6, 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 PCB submission: Tuesday, October 13, 11:59 PM

When your 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 help, no questions asked.) After you submit it, take a screenshot of your order confirmation and upload it to the Project 2 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).

Project #1: Build a breadboard power supply #

The first project is to build a power supply with the following characteristics:

  • 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 PCB submission): Thursday, September 22, 11:59 PM

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.

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.

breadboard power supply

The image below shows the rough 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 follow the pin location dimensions shown below. You don’t have to have pins where all of the 8 red dots are– you could get by with just 4, but 8 will make the board stay in place a little more securely.

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 two 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.

P1 prototype: what you should do before class #3 (before Tues., 9/13) #

  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 comes out, as shown on the website diagram. You’ll need to use your 5V voltage regulator component.
  3. Install Kicad.
  4. Watch the Kicad demo videos, a total of 5 minutes, 59 seconds for the first two demo videos
  5. If you can absorb material from books efficiently, read as much of chapter 2 from the Practical Electronics textbook as you can.

Project #0: Power an LED with “wall” power through our DC power supply. Control it with a push button. #

The getting-started “project” is really more of a warm-up activity, and we’ll do it together in class. The goal is to create a circuit on your breadboard that powers an LED with power from the wall, directed through your kit’s DC power supply. This circuit should have the following characteristics:

  • It is implemented on a breadboard.
  • It accepts power from a 2.1 x 5.5 mm plug from a 12 V wall adapter.
  • It turns on an LED when a push button is pressed.

Due date (for submitting a photo of your circuit to Canvas): Thursday, September 8, 11:59 PM