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I've been watching YouTube: https://youtu.be/YYKlfFYTl-8. Can you tell me is this dangerous or not to do at home?

So I've been watching this video, and I've wanted to do it myself, but to the number 67000V is scary.

I looked up what is the upper limit of safe voltage, and it says it should be at around 200V for DC (I'm pretty sure this is DC cause he says at 1:30 it's battery powered, please let me know if I am wrong).

But than I came across to a similar question on this site, and the last answer is saying something like "the voltage does not say if something is dangerous or not, but the current does" after that the writer tells that people already died from a voltage of 42V, but he knows that there are special Van de Graff generators that generate a extremely high voltage and are safe to touch. He actually also touched a one and a half million volt Van de Graff generator and there were no negative changes. Please tell me who is lying and who is right, am I safe to build this at home, and if so, am I supposed to use some special caution or something like the "one hand rule"?

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    \$\begingroup\$ "If you have to ask..." \$\endgroup\$
    – TypeIA
    Jul 7, 2023 at 19:58
  • \$\begingroup\$ Welcome! I took a peek at the video and description and could not find a schematic. Schematics are the preferred way to communicate the details of electronic circuit due to their orderly, standardized, and easier-to-read nature, as compared to a video. Could you include a clear schematic of the circuit as you intend to build it, in order to ensure that we're on the same page and ensure that our answers are applicable to the way you interpreted any ambiguities from the video? As you yourself pointed out, the answer depends on a lot of factors, and knowing those factors accurately is critical. \$\endgroup\$
    – nanofarad
    Jul 7, 2023 at 19:58
  • \$\begingroup\$ Well, dangerous depends on circumstances. You can affect the function of a cardiac stimulator or other implants and burn a little hole in your finger. The capacitor stack of 1 nF capacitors in series can not store dangerous energy levels. \$\endgroup\$
    – Jens
    Jul 7, 2023 at 20:05

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No, there shouldn't be any risk while doing what it is shown in the video. What it is lethal is the current that flows through your body, not the voltage itself. By convention, considerate that \$30 mA\$ during a period higher than \$500ms\$ is the limit of a current to be ‘safe’ (look the IEC 60479–1 graph on Wikipedia article). If you look at the circuit breakers, most of them cut the power when they detect a leak current at this value or near this value.

At \$50 Hz\$ frequency, the resistance of human body is around \$1k\Omega\$. So \$42V/1k\Omega = 42mA \$, this can kill someone if isn't lucky enough.

On the other hand, most of the voltage multipliers, like that which is shown in your video just consist in a bunch of capacitors which produce a high voltage but aren't capable of producing a high current in a considerable interval of time. Since the math makes us feel safer, think it this way: there are 18 capacitors \$1nF\$ and estimate \$5 kV\$ for each capacitor. The total charge is: \$18 \cdot 1nF \cdot 5 kV = 90uC \$. The conditions changed beacuse this is DC, your resistance will be higher, but a current of \$30 mA\$ would discharge the system in \$90uC / 30mA = 3ms\$. So, even if you had this amount of current the time of the shock would be much slower than what is considered dangerous.

If you touch some conductor of the circuit, you will be shocked but that shouldn't kill you or cause serious damage. Actually, this is the principle of the picana.

P. S. If you disconnect the power supply from the tower the capacitors will remain charged, so if you touch them you will be shocked too. To discharge them just connect a megaohm resistor between positive and negative terminals of the board—or you just could short circuit the terminals but you risk the lifespan of the capacitors.

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    \$\begingroup\$ Discharge capacitor with screwdriver? Mehaohm resistor should be used. \$\endgroup\$
    – user263983
    Jul 7, 2023 at 21:01
  • \$\begingroup\$ Good to know it, I always connected the terminals directly \$\endgroup\$
    – tac
    Jul 7, 2023 at 21:13
  • \$\begingroup\$ @user263983 there might be a problem in finding megaohm resistor with 67 kV rating... \$\endgroup\$
    – Rokta
    Jul 7, 2023 at 23:09
  • \$\begingroup\$ @rokta so, you can suggest somebody the action, that can bring to damage the capacitor, wires or screwdriver? Damaging resistor is less important and rating voltage is for constant work. Cost of resistoris ≤1¢> \$\endgroup\$
    – user263983
    Jul 8, 2023 at 2:51
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    \$\begingroup\$ Screwdrivers can have material burnt away from discharges like that and that material can impact other things. I have a screwdriver or two with similar damage, also have a pair of sidecutters with a chunk missing from the cutting edge due to someone chopping a live wire. Annoyed with them as they did not check the supply was off. \$\endgroup\$
    – Solar Mike
    Jul 8, 2023 at 6:03

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