I spent the past several weeks working on a variable-voltage charger for a capacitor bank. The initial concept was to use a relay controlled by a feedback circuit with an adjustable voltage divider and comparator. That worked, so I decided to go modern and use a high-side P-channel mosfet to replace the relay. The parts worked on breadboard, but when assembled on a PCB there were lots of problems. My amplifier oscillated. There were lots of nasty transients. Those problems were solved by a sprinkling of capacitors. I got good voltage and stable switching of the mosfet, until I tried to pull any real power. At that point, the mosfet almost glowed. I added an inductor – after all, it was basically a crude switch-mode supply. Things got a lot better. So then it was time to redesign, order parts, and wait. In the meantime, I continued to work on it with the parts I had on hand and a little scavenging. Well, I finally got it working today. I get more than 6A to a resistive load and the mosfet barely gets warm. UPS will come tomorrow with the new parts.
I suddenly realized that this episode followed a consistent and familiar pattern. I have a design problem, order parts, continue to work on the problem in the interim, and the UPS man arrives at almost the precise instant when the problem is resolved with the parts I had on hand.
Has anyone else noticed this strange resonance between cerebration and United Parcel Service delivery? Just how does UPS know the precise instant when you no longer need the parts?
I propose that this newly described phenomenon be called Cerebral UPS resonance (C.U.P.S). Best regards. John
I suddenly realized that this episode followed a consistent and familiar pattern. I have a design problem, order parts, continue to work on the problem in the interim, and the UPS man arrives at almost the precise instant when the problem is resolved with the parts I had on hand.
Has anyone else noticed this strange resonance between cerebration and United Parcel Service delivery? Just how does UPS know the precise instant when you no longer need the parts?
I propose that this newly described phenomenon be called Cerebral UPS resonance (C.U.P.S). Best regards. John