Issue link: https://iconnect007.uberflip.com/i/1441485
28 DESIGN007 MAGAZINE I JANUARY 2022 High Voltage PCB Constraints Way back in my early 20s, I was tasked with repairing Marconi HiPot testers. ese ancient, bulky machines were basically high voltage generators used for testing the dielec- tric withstanding voltage or isolation of 50KV high voltage power transmission lines that are strewn across the countryside. Opening the box, you see a string of diodes and several huge, high voltage ceramic capacitors creating a voltage multiplier. I used to wind these up to a humming 60KV and they sure packed one hell of a punch (even when switched off ), as I soon found out. is instilled in me the impor- tance of spacing to isolate high voltage. Testing this lethal weapon was an ordeal. I used to position the output cables about nine inches from either end of a 240V three-foot fluorescent tube and stand well back; a crack of blue light- ning arced across the gaps and ignited the tube as I wound up the voltage. I felt a bit like Nikola Tesla in his Colorado Springs lab surrounded by high voltage discharges (Figure 1). However, Beyond Design Feature Column by Barry Olney, IN-CIRCUIT DESIGN PTY LTD / AUSTRALIA Figure 1: Multiple exposure photo of Tesla in Colorado Springs lab. (Source: Wikimedia Commons)