Just a few words before you go and build some of these, or other projects. I would like to remind everyone that while tube audio DIY is really fun and cool, there are some things to remember. Most tubes work at voltages exceeding 100V, this is potentially lethal and care should be taken before turning on any power that all connections are correctly made and that you use every possible safety measure to assure you don't get electrocuted. Always triple check what you are doing and if you are not sure, ask someone who has experience with the topics in question.
Below I have included some pics I made of my own errors or mishaps. Even though I am talking about them in a mild manner, each mishap could just as easily have caused serious injuries. Most mistakes are not made during designing, but during building and testing.
During my last project (Assault & Battery) I was using a bunch of 12V batteries connected in series to get a B+ for my tubes. I have been using them for a few weeks with no mishaps, until this series of pictures was placed. My enthusiasm is sometimes spiking at the hours between 11pm and 2am. This is when I get all my creative brain spasms and absolutely have to try out that one idea before I shut everything off and go to bed. The last bright idea I had was to hook up 32 batteries so I could try out some 10Y on my power amps and compare them to the 71A I am using currently. All went well on the first mono amp, but the second caused a little problem. I was a bit careless while lying down and hooking up the clip-lead underneath the amp. It was a tight fit and I could just get the alligator clip onto the capacitor pin. I always hook up from rear to front, so the power goes on when all wires are already connected to the appropriate pins.
Well.... let me tell you... The second I pushed the clip onto the + pin of the last battery something blue flew out of the battery. When my reflex had stopped moving my arm I understood it was an arc of about 6 inches emanating from the point where the battery and clip-lead had met. Just as I knew what happened I heard something in my amp sizzle and start to smolder. I quickly turned over the amp (40 lbs) just in time to see the other end of the clip-lead shedding it's plastic insulation and remove itself from the wire. No fire though, bummer...
Within half a second the batteries pushed so much current that both ends of two clip-leads had either been welded to the part is was hooked up to, partially evaporated or just melt the entire insulation off. The first person to tell me batteries are 'slow' will be the one to test the new nipple clips hooked up to the 416V... Sheesh, the power in these batteries is amazing. At 12V you don't pay much attention, but connect 32 in series and I will be a lot more careful in the future.
I strongly recommend that anyone that tries to use batteries like I did, to put a fuse in somewhere. These things are killers!!!