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I'm usually too scared to work with anything over 120V- especially since parts on the schematic linked require a 1000V power supply to work. Very neat, but too
by kregasaurusrex 8y ago
I'm usually too scared to work with anything over 120V- especially since parts on the schematic linked require a 1000V power supply to work. Very neat, but too dangerous for the average home-gamer like myself to be inspired enough to go out and build.
- raverbashing 8y agoAnd you should be. It can be worked safely if you follow necessary precautions, but unless you are familiar with those, better follow the disclaimer and "do not try this at home". The main issue is that capacitors keep their charge after unplugging, so you might have some that are still dangerously charged. I remember when opening old CRT TVs they had a big notice inside about discharging them before servicing some parts of the circuit.
- CamperBob2 8y ago1000V, at the current levels needed for this application, amounts to the juice behind a good carpet shock.
- kragen 8y agoDunno about the Monoscope in particular, but a lot of tubes need several milliamps, which is quite a bit more painful than a good carpet shock. Not fatal, but not something I'm eager to experience. And I'm the guy who used a one-henry inductor to administer electric shocks to people in high school — including, repeatedly, myself. The issue is that it's a lot easier to build or buy a kilovolt power supply that doesn't have adequate current limiting than one that does. And even one that has it in theory may not have it in practice — that big capacitor across the output? Make sure it isn't just wired directly to the output terminals, because its ESR sure as hell isn't going to be adequate current limiting. So I think it's reasonable to be wary of kilovolt circuits. Dying is easy, but you only get to try it once.
- lightedman 8y ago"The issue is that it's a lot easier to build or buy a kilovolt power supply that doesn't have adequate current limiting than one that does." You can buy Van de Graaf generators all day long. Quarter-million volts minimum for $200.
- kragen 8y agoLightedman's dead comment, in response to my, "The issue is that it's a lot easier to build or buy a kilovolt power supply that doesn't have adequate current limiting than one that does," said, "You can buy Van de Graaf generators all day long. Quarter-million volts minimum for $200." While van de Graaff generators are indeed relatively affordable, and indeed some even cost less than US$200, a working microwave oven costs US$60, and a broken one can be had for under US$10. Furthermore, a safe van de Graaff generator is not actually capable of supplying enough current at the high voltage to operate a vacuum tube, while a deadly microwave-oven transformer is; and there are orders of magnitude more microwave ovens available.
- jacquesm 8y agoA KV from a half decent supply will throw you across the room in a bad case and give you a nasty burn in a slightly better one. Don't underestimate the power of a HV supply, especially one that has some nice stabilization and caps.
- tubetime 8y agomy power supply is capable of 1KV at 10mA. it's the one piece of lab equipment i own that genuinely scares me. all this stuff has to be treated with respect. still though it's good for cool experiments with monoscope tubes. :-)
- CamperBob2 8y agoIn other news, you don't need 100 watts worth of HV to run a CRT.
- zaarn 8y agoA good GFCI, safety equipment and respect go a long way. Especially the first one saved me more than a dozen times at this point. Yay for required-by-law GFCI on the house-level. I also do recommend to get some Schuko (CEE 7/3 and CEE7/4) or UK plugs and sockets, even if you're in the US just so you can avoid the safety nightmare that is the US plug. (Thuogh I'm not sure if you can do them as permanent installs in the US... they're still neat for lab equipment) edit: you should have respect for anything about 50V or so, after that point it can be quite dangerous. 120V is way above where i start using safety equipment.
- kosma 8y agoNo GFCI will save you on the secondary side of a transformer. My point is: working with standard 120/230V requires just following codes and guidelines. Tinkering with HV in non-standard setups requires understanding of how and why.
- jacquesm 8y ago50 Volts and the right conditions can kill you just fine. Always be careful.
- c3833174 8y agoWaay too boring following the safety police rules. Playing with HV can be fun, just build fly swatter-level inverters instead of using a transformer/capacitors big enough to kill you. A CCFL inverter from an LCD screen is a good start, you can light neon bulbs and gets ozone
- tubetime 8y agothose are dangerous too--they output high frequency AC which can cause burns. with a thumb-sized CCFL supply i once burned a tiny hole in my finger. never bled a drop since the current cauterized it but it hurt for a week.
- c3833174 8y agoYou can burn yourself with a soldering iron or splashed solder too, better avoid electronics all together.
- dfox 8y agoThe fact that you can burn yourself with soldering iron is mostly obvious. That CCFL inverter can easily burn hole through you finger without you noticing it until it's too late is not that obvious.
- CamperBob2 8y agoYou'll live.
- dfox 8y agoIn both cases with overwhelming probability. But there is difference: you have to be extraordinary clumsy to get life-threatening burn from soldering iron, but you can get life threatening burn from HF HV very easily.
- 8y ago
- tubetime 8y agoyou've got to be very careful and never use HV without treating it with respect. i use the one hand rule extensively, keeping my left hand firmly tucked behind my back while the supply is turned on.