by Jacob M.
In the spring of 1991, I was given an opportunity to prove we could build power supplies in SEM-E format. I borrowed a low-speed saw from the failure analysis lab and cut a 3019 pot core down to a 3008. Jim Rockwell, then a technician, cut 48 inches of 2 mil Nomex® and 2 mil copper tape holding 0.005 inch tolerance with nothing but a straight edge and a utility knife. We stuck the transformer in a lash-up bread board that Jim put together in half-a-day and started easing up the load.
Somehow, I misunderstood the current sense coefficient. Instead of easing the load up to 280 watts, I eased it up to 560. I wanted to make sure it would go to 120 percent, so I was leaning over to watch the oscilloscope. Justin Fong was standing on his toes, leaning over my shoulder. Somewhere over 600 watts, it started spitting molten silicon. I backed up so suddenly, I carried Justin about 10 feet draped over my shoulder. Justin said he thought he had been hit with a new kind of kung fu. It was primitive, fast, fun engineering. With the right team, it was the best kind!