In 2005, I won my first SBIR award. At the time I was finishing a postdoc at Lawrence Livermore National Laboratory, and the award let me chase an idea I’d been chewing on: the repetitive injection of plasma into a flux conserver. It was a small system, a small budget, and a small team — really just me and whoever I could convince to help.
We built everything from first principles. Capacitor banks, control systems, timing electronics — all of it designed and machined ourselves. We even tried turning the domes for our own spark gaps on a lathe. It didn’t always work. But that was the point: figure out what the physics actually needed, then build exactly that, with whatever tools and materials got us there fastest.
I’ll write more about that first system and what came of it in a future post. This one is about what happened next — the long evolution from that first plasma injection experiment to a capacitor bank we designed, almost a decade later, for a research organization on the East Coast.
Phase II, and the Home Depot era
Our first Phase II SBIR came with a budget that, in hindsight, was tiny for what we were trying to do. We needed a full set of capabilities — fiber-optic control systems, charging relays, switching, buswork, diagnostics — and we needed it on a shoestring. So we built it that way.
The charging relays were modified lower-voltage relays we adapted ourselves. Most of the small components came from Digikey. A lot of the rest came from Home Depot. The frame of the bank itself was made from wood.
That wasn’t a stopgap. It was a design philosophy that stuck. If we didn’t need to weld an aluminum support structure, and 2x4s would do the job, we used 2x4s. Every choice on that project asked the same questions: How do we cut the cost of this part? How do we cut the cost of assembly? And — the one that mattered most in the long run — what happens when the customer wants to reconfigure the bank next year?
We answered that last question by building everything to be modular from the start. Capacitors, switches, buswork, dump — each a discrete, swappable sub-assembly rather than a single fused design. It made the first banks cheaper to build and easier to change. It also turned out to be the design principle that shaped nearly everything we’ve built since.
Those early banks became the intellectual foundation of the company. More on that in the coming weeks.
A decade later: same principles, a different level of rigor
The EF Capacitor Bank Module came much later in that series — close to ten years into the company’s history. By then, we weren’t machining spark gap domes on a lathe anymore, but the underlying instincts hadn’t changed: modular sub-assemblies, a clear-eyed view of cost at every step, and a bank engineered to be reconfigured rather than replaced.
What had changed was the process around it. This design went through multiple iterations and a genuinely rigorous review cycle, with input from the national laboratory where the bank was ultimately headed. By that point, we had the details of capacitor bank design at our fingertips — decades of accumulated judgment about fusing, crowbar timing, buswork inductance, dump sizing — but the design review process is what turned that judgment into something a national lab was willing to sign off on and run for a decade.
The result is a bipolar, phase-control-thyristor-switched capacitor bank, crowbarred at peak current, self-contained on two standard pallets, and built to a 100,000-shot, 10-year design life. It’s been running in continuous service at its customer site since 2016.
It’s a long way from a wooden frame and a Home Depot parts list. But it’s the same company, asking the same questions it always has: what does the physics actually need, and how do we build exactly that — no more, no less?
Click here for full specifications for the EF Capacitor Bank Module.
By Dr. Simon Woodruff, CEO — Woodruff Engineering Inc.