Hi At the moment I am trying to design a variable HV psu for some projects (some of which haven't even been though up yet, but I want to ability to run everything for hv off of the one psu). The idea is to use a transformer(which would double as an isolation transformer) with a 600:2500 ratio to convert the 240V ac in to 1000v (E(secondary)/E(primary)=N(secondary)/N(primary)) then feeding this into an 8 stage cw multiplier for an output of roughly 10,000V dc (8*sqrt(2)*1000v=11313, or 1313V worth of 'v drop'). This would then have some 'stuff' happen to it to vary the voltage (refered to as 'stuff' here as it will be detailed later) and would then end up in a switching system for either a dc output, a pulsating dc output (using a vacuum tube triode hooked up to a variable frequency ocilator) and ac (by applying the pulsating dc into a 1000:1000 transformer). Now for the 'stuff' part. I was originally thinking of using 2 rotary switches (value+multiplier) to control which output from a massive (2,000,000 ohm total) potential divider (v=IR therefore V/I=R, 10,000/0.005=2,000,000) in order to maintain the output current at roughly 5miliamps (which would hurt, but probably not do much else). Unfortunately, this creates an issue wherein the power (V*I) for the divider to dissipate is soemthing in the vicinity of 50W, way more than any of the 1/2W film resistors I have available can take. Any ideas as to how this could be accomplished? Since I have to get some mineral oil for the multiplier anyway, could I improve the ability for the resistors to cope with this heat by placing them in a tube of mineral oil and cooling it using a pump and 120mm radiator? Is there a way this can be accomplished using some funky circuitry and a vacuum tube triode instead? Other than the issue of changing the volatge output, how do I 'complete' such a circuit in a way to prevent earth potential rise? I know that for the ac out, it would be through both outputs of the transformer secondary, but for the dc and pulsating dc, where do I loop it back to (using the neutral or ground on the power cord would probably cause an earth potential rise and/or break something. Safety is a big deal for this and so the ideas were that there would be a) indicator LEDs for when it was powered, for when it is turned on and which output is connected b) a rocker switch on the active line in, a button to check if the case is closed and having the actual ouput ports inside a bit of PVC tube, with the cable passed through a cover and another button to check if the cover is in place (can't remove the cord if powered on) & c) have the actual power switch with a 'missile lock' so it can't be knocked on accidentaly. Anything else that should be done?