Category Archives: Circuits & Electronics

Small AC-DC converter

One of my goals recently has been to make a small (no transformers) application-specific AC-DC converter. Here are the specs I need to meet:

  • Iout > 15 mA (DC)
  • 3.0 V < Vout < 32.0 V (DC)

The reason I was planning for these specs is because I am testing my converter with a solid state relay (SSR) that is driven by a DC input of 3 V, 15 mA minimum, and connects an AC load of up to 240 V, 10 A maximum. I am trying to keep the power consumption of my circuit down, so that means I need to try to keep both the voltage and current as low as possible. Here are some of the paths I may try to take: Continue reading Small AC-DC converter

Senior Capstone Project – Frequency Synthesizer

It looks like our capstone project will be changing. Instead of doing the Assistive Technology project, we will be designing a frequency synthesizer for someone’s project at Wulfsberg Electronics in Prescott, AZ. It looks like it will be a very complex project, and may include some of the following:

  • Designing a VCO.
  • Update an existing PLL chip to with step sizes that are selectable for 8.33 kHz, 12.5 kHz, and 25 kHz steps.
  • Design the control loop filter for the PLL.
  • Design / select a buffer amplifier.
  • Layout the PCB for the design.
  • Testing for all of the above.

We probably won’t do all of the items listed above, but the project will be challenging and fun! I will update this post from time to time.

Update:
View this web page for more info on this project: mike-thomson.com/school/Wulfsberg/

Senior Capstone Project – Assistive Technology

Today we are finally getting our project assignments for EE 486 (our Electrical Engineering senior capstone project.) We were supposed to get them last week, but one of the project sponsors (who was actually sponsoring 3 of the available projects) backed out. This meant that three teams got the projects they picked, and the other three teams (including mine) were stuck to choose from only two remaining projects. Since then, another project has popped up, and I think we are going to get the project that we originally wanted.

The project we want, and will probably get, is with the College of Education (COE) and the Institute for Human Development (IHD) here at Northern Arizona University (NAU.) The projet will consist of Assistive Technology and Audio-Video systems for classrooms. We have some ideas already of the mini-projects that we might include in this, but we will be having a brainstorming meeting with some faculty and students to determine what kinds of technological needs may be present in the classrooms.

In the next couple of weeks, and over the course of the next 9 months, this topic will be updated quite a bit with the progress we will be making.

Junkyard Generator – update

My group and I have finished our junkyard generator. Here is an overview of what we did (click on the images below to go to bigger versions of them):

The frame was initially made out of steel. Sherman did a good job with this (I will try to get a picture of it to put here.) We quickly discovered that the magnets in the generator had too much of an attraction to the frame and made spinning the axle very difficult. Chad then made the frame out of wood. Continue reading Junkyard Generator – update

Junkyard Generator

I am taking an electromagnetics course this semester, and our first project is getting into groups and making a human-powered generator that can light a bulb. It is actually a pretty fun project. We have to use “junk” that we find, and can spend no more than $10/person in the group. There are 5 people in our group, so I don’t think the money specification limits us very much. So far it looks like we will spend a total of $5 (for the entire group, not per person.)

Here are some interesting and useful tidbits we have learned so far: Continue reading Junkyard Generator