Custom circuit boards designed alongside the machines they run, so the electronics, harnessing and enclosure fit together and can be built, tested and serviced.
Treadmill display: from wires in headers to a real board
A commercial treadmill display had gone into production as an early Arduino-based prototype, with wires pushed into header pins, and had stayed that way for years. The goal was to keep its look and fix everything behind it. This was done during my years as a product developer at a Connecticut contract manufacturer.
The new circuit was proven on a breadboard first, then laid out as a dedicated circuit board. The new display added static and reverse polarity protection, an efficient switching regulator and a low-battery warning. It ran much longer on a battery charge and cut assembly work substantially. Test code checked that every LED was addressed correctly, and the assemblers were trained to program and troubleshoot the boards.
Before: the Arduino-based display (right). After: the new board (left).
The circuit proven on a breadboard.
The new board.
Same look from the front.
Vending machine control boards
Modular control boards for a robotic vending machine, designed as part of a collaborative project.
The boards were made in the first months of the chip shortage, and rolling shortages forced about four revisions before manufacturing. Communication runs over RS-485 so it could integrate with existing hardware. Three modular control boards were made, some serving double duty across configurations, with one firmware (written by a collaborator) for every satellite board to check its address and carry out its tasks. Every input and output is static and short-circuit protected.
One of the modular control boards.
Industrial controller for a food-waste liquefier
For a food-waste liquefier, an existing prototype machine was refurbished and evolved: better function, a clearer operator interface, and an overall better design. I did the controls wiring, the circuit board, and the graphic and operator interface design. Others handled the sheet metal and the PLC and Linux programming.
The controller uses a Linux small board computer and shows every normal operating parameter in one view, with an indicator LED on every digital input and output and socketed wear parts for quick field repairs. About 120 hand-wired screw terminals became a handful of plug-in connectors, and controls and harness assembly dropped from about 30 hours to about 3, by my estimate.
Built for a rotary weld positioner and handheld roller: it runs a stepper motor at adjustable speed, with an optional step-back function that has adjustable timing, to give welds a consistent “stack of dimes” look. Inputs are static protected and current limited, and it uses an off-the-shelf stepper driver chip. The design was later built into a reverse osmosis water system to adjust its waste and recirculation flows.