Sparky’s first spark-board resistor was 100ishR, 1/8W, and the magic smoke escaped instantly. The second was 50R, a couple of orders larger in wattage, and much much bigger, and made of metal. After we’d been running the spark table for a while, there was a wisp of smoke from the table, which was starting to melt. So we found four of those in an array, and we wired them up to give us 50R, and they get uncomfortably hot to touch. They’re mounted on an aluminium plate.
Today, Mat converted a lump of car radiator into a heat sink, drilling and tapping all the holes necessary to fit five waaaay chunkier 10R resistors on so we can wire them up with crocodile clips. If we need to water cool them, we can borrow some resistors from someone I know who worked in sound. If /that/ fails, he was telling me about spikes and power switching, and that’s a spare thought. However, this array ought give us a good range from 2-50R, depending on how we wire them, and if 2 Ohms doesn’t set fire to anything, we’re likely to stick with that.
Today, I helped by making tea and not getting in the way, and as a san-check on the positioning of the drill holes, and I also learned a bit about clamping. Mat helped by doing all of the work, and not fucking it up, and also by making tea.