Question: Voltage Multiplier Safety

[Djf321]

I want to build a safe Villard cascade voltage multiplier so that I can create sparks that I can touch without dying or being injured. Is it possible to do this? And if so how would you construct it (specifically what capacitors and rectifiers and power source would be used)?

My second question is that if this can't be done or done easily, are there any type of non-mechanical spark machines (not Van de Graaf generator or Wimshurst machine) that can make safe sparks that can be touched? If so, how do you make them?

[Moderator's note: Approved.]

 

[Guineafowl]

I’ve made a couple of these.

Obvious safety features would include ensuring you can’t touch both terminals simultaneously, and get a hand-hand shock, fusing and some sort of key switch so ‘unintended operators’ can’t switch it on.

If mains-powered, a 1:1 isolation transformer is a must, be-all-end-all, sine qua non... The rating doesn’t have to be high, as these devices draw piddling currents.

Capacitors I used were ceramic or polyprop, rated to twice peak voltage (I went with 1 kV). Why not try class Y 1 nF?

Rectifiers were 1N4007.

Best build strategy if to breadboard it out until satisfied. That way, you can test voltage using a string of 1 M resistors as a voltage divider, inrush, idle and short-circuit current (for fuse rating) and general performance.

The number of stages determines voltage, while the capacitance determines energy storage. Start with a two stage; 1N4007 diodes and class Y 1nF capacitors. Move on from there.

 

[Baluncore]

I want to build a safe Villard cascade voltage multiplier so that I can create sparks that I can touch without dying or being injured.

There is no such thing as a safe spark to the human body. Each spark burns a few cells below the surface of your skin. You must hold a conductor between the spark and your body to prevent micro-burns and UV exposure where the plasma formed by the spark reaches your body potential.

 

[Djf321]

So I'm still a little confused. I'm assuming that for a Villard cascade voltage multiplier that there is some formula that gives the output voltage given the input voltage, the capacitor's capacitance, and the number of stages. Also, I'm assuming there is some formula that gives the power output that again depends on the input power, the capicitor's capacitance, and the number of stages.

So my question is, what are these formulas? And what is the output voltage and the output power that I should configure that is safe to touch (won't stop my heart and won't hurt too much)? I don't know what these values would be.

Also, to GuineaFowl:
You suggest 1 nF capacitors, but was the Villard cascade voltage multiplier that you made actually safe to touch both output terminals with your hands? This is what I would want to be able to do as this will be a demonstration model and there may be someone who accidentally does this. I don't want them to get hurt. In parts of your response you seem to imply that it isn't safe to touch (your setup).

 

[Guineafowl]

So I'm still a little confused. I'm assuming that for a Villard cascade voltage multiplier that there is some formula that gives the output voltage given the input voltage, the capacitor's capacitance, and the number of stages. Also, I'm assuming there is some formula that gives the power output that again depends on the input power, the capicitor's capacitance, and the number of stages.

https://en.m.wikipedia.org/wiki/Cockcroft–Walton_generator

You suggest 1 nF capacitors, but was the Villard cascade voltage multiplier that you made actually safe to touch both active hands with your hands. In parts of your response you seem to imply that it isn't.

Well, mine weren’t designed to be touched at all, but I used much bigger capacitors. By touching with both hands, you’re somewhat defeating the purpose of the isolation transformer. Do you really need to do that?
Lethality of shocks is multifactorial - direction of current, volts, amps, time (ie energy). I would hesitate to present you a circuit design and certify it safe, given that it’s for deliberately shocking yourself.

 

[anorlunda]

Temporarily closed for moderation.

 

[anorlunda]

Thread reopened.

 

[anorlunda]

I can't recommend any safe way that is tied to a circuit with unspecified power supply connected to mains. We don't know about experience, or supervision, or safety precautions, or even the purpose of your project. You could be making a weapon.

A simple non-lethal way is to use a bug zapper. They look like badminton rackets, and are battery operated.

For a dramatic and safe experiment, rub a cat's fur, or shuffle your leather shoes on the rug in winter, then touch a grounded piece of metal. You see a spark, hear the noise and you'll say ouch. Static electricity like that can be 20 to 30 thousand volts. But because the energy is low, it is safe. I used to get a shock like that touching the door handle of my car in winter.

 

[DaveE]

Have a look at this. VMI has other good application information on their site.
http://www.voltagemultipliers.com/pdf/Multiplier%20Design%20Guideline.pdf

 

[fresh_42]

I want to build a safe Villard cascade voltage multiplier so that I can create sparks

The answer is relatively simple:

Piezoelectricity or static electricity are relatively harmless, circuits are not, especially as your 'spark' could easily result in an exposure which isn't short in time anymore. This makes it dangerous. I thought by a spark you meant something which e.g. could ignite a lighter. Multiplier circuits are not meant to create 'sparks'.

Your project can even be life threatening, since you cannot be sure about any medical preconditions like heart malfunctions or hidden defects people might have - including yourself!

Thus our recommendation can only be: hands off! See e.g. https://www.pbs.org/newshour/show/police-killed-1000-people-tasers-since-2000

Thread closed, as the subject turned out to be too dangerous to make any responsible recommendations.