Jay(son) Bunnell

My current upcoming project is a layout engine for Typst (a Latex alternative) that uses a nodegraph system to resolve the positions of a circuit relative to ground. This enables typsetters to define circuits similar to a Netlist, the common representation of SPICE simulators. The intuition this brings to typsetting provides a pretty clear advantage to someone like me, who often typsets projects for fun.

It uses nodes with fixed definitions (i.e. Ground as (0,0)) and traverses a graph of all of their connections. Because each component has a defined size and orientation, all the nodes can be calculated from here. The minimum size of the circuit gets calculated based on this node graph, giving a reasonable start to a layout. Width, height, and style changes can be done arbtrarily based on input parameters, and because the whole thing is within a block level element and drawn as an SVG, it an be resized for any use-case.

You can view the details of drawing a circuit in the image description on the right.

An Open-Source 3D printer based on the Lulzbot TAZ6 capable of extruding biomaterials. We designed it to use the TAZ6's original motor, and did some clever tricks to convince the TAZ that it was interfacing with a regular plastic nozzle. A huge benefit of this is that future updates of Marlin, the TAZ's firmware, are fully compatible with our printer.

This project required writing loads of GCode by hand, and learning a great deal about what REPRAP-style printers do. All of the modifications to typical slicer settings (Cura) are documented along with the printer, and are currently held by Utah Tech University. Contact Dave Christensen for access to the design files.

My major contribution (besides programming and designing our test prints) was the temperature regulation system, which provides a convenient user-interface to a set of 140CFM fans embedded in the table. Air filtered through hepa filters in the side of the central enclosure (see image) gets exchanged in the printing area, allowing the temperature inside to remain stable. All of the formulations designed for this printer so-far are meant to print at room temperature, and the printer being enclosed is a huge source of heat.

A KiCad-10-designed regulator that can buck or boost 12V all the way up to 100V and all the way down to 1V, with minimal ripples (under 330mA and 80mV). It uses two LM555 timer chips from Texas Instruments to allow for independent control of frequency and pulse-width, and its updated schematic uses closed-loop voltage control to change the pulse-width to hit a target output voltage.

The components in the schematic are rated for 2 Amps at 25 degrees, which allows the energy transfer capacitor C5 to withstand transients from switching. I would happily build this again, but would likely decide on a larger footprint board with no surface-mount components. The SMD MOSFET used required a heatsink, and still had issues with temperature due to its size. Through-hole MOSFETS in parallel would be satisfactory for a converter like this one, especially running as slow as 50kHz.

The UI/UX, control system, power distribution, and microcontroller brain for a dual BLDC motor modified pedalboat were handled by myself and a Mechatronics engineer, Jacob Galindo. This was my first project using currents above milliamps, and was a huge success due to several late nights and some creative problem solving. I think designing a circuitboard for this project would have saved me a huge amount of time and patience soldering, as all of the components had to be individually soldered to a protoboard embedded in the waterproof controls box.

The system is controlled by feedback from two potentiometers, each controlling the thrust provided by one motor. A Gyroscope chip measures boat heading, relaying that information back to the drivers of the craft. The speed controllers for the motors also measured temperature and spin rate, which were useful to provide backward.

If I were implementing this sort of control now, I would calculate a heading based on the two inputs and correct the thrust of the motors based on the difference from the true heading, measured by our gyroscope chip. This would have provided additional consistency and made the user experience a lot more streamlined for new users of the boat. After competing, several team members drove the boats with their families (mine included) to give them a taste of what hands-on engineering meant for students at Utah Tech.

I post here often, especially about whatever's interesting in the moment. My posts are never written by generative AI.

If you're reaching out for a business inquiry, please mention it in the subject. If you're not reaching out for business, I'm happy to be friends!

I have switched to using Codeberg as my main development platform. It is similar to Github or Gitlab, if you're familiar with either of those. This site is hosted on Codeberg.