After reading a shopping magazine, one of its products featured a stun gun the size of a large wireless car door opener* with the ability to produce two million volts. How can a small device electronically produce two million volts?

*Exact dimensions are 3.65"x 1.15" x .6"

Edit: As requested, here's the product's link: http://www.heartlandamerica.com/browse/item.asp?product=keychain-stun-gun&PIN=170414&BC=S&DL=SEH1

  • \$\begingroup\$ Can you share a link to the device? Shopping magazines may not be the most accurate form of truth! \$\endgroup\$
    – Andy aka
    Dec 28, 2013 at 16:31
  • \$\begingroup\$ Added the link to the post :) \$\endgroup\$
    – slippery
    Dec 28, 2013 at 16:38
  • 2
    \$\begingroup\$ Rule of thumb is that you need about 1kV to get a spark across a 1mm air gap. With 2MV would mean 2m in open air. I doubt that the device does that. I doubt you should want to hold a device that does 2MV in your hand. \$\endgroup\$
    – jippie
    Dec 28, 2013 at 17:04
  • \$\begingroup\$ Voltage is the potential energy held by a charge in relation to an electric field, divided by that charge: it is a per unit charge measure of potential. When you have a fraction, you can make a big value by using a small denominator. \$\endgroup\$
    – Kaz
    Dec 28, 2013 at 17:17
  • \$\begingroup\$ Shopping magazines, car salesmen, computer salesmen, bankers and politicians can achieve almost anything, apparently. \$\endgroup\$
    – Russell McMahon
    Dec 28, 2013 at 19:16

2 Answers 2


Generating high voltage is not a problem with low current.

For example take the electric lighter who produce a really high voltage to create a spark that will fire the gas. When things start to be complicated it's when you start to get a load that drain more current. These devices draws only few µA and should, without that they could be really dangerous (for you and your opponent).

But even like that they could create some severe damage. So \$I = V/R\$. Let's take a body resistance of 10K.

\$ 2 000 000 / 10 000 = 200A\$

But it's totally theorical as the device can't produce 200A. (You'll get out of battery or get your hand on fire before :p) But you don't need 200A to knock out someone. Take a look at the table here to figure out what can happen.

For the technical side it's basicaly a bunch of high voltage capatacitors.

Here's an example for a lighter :

enter image description here


Keep in mind that shuffling your feet across the carpet can generate tens of thousands of volts, as does an old fashioned photoflash or the igniter on your gas grill. Automobile ignition systems used to rely on a very simple step-up transformer where a capacitor charged to 12 volts was discharged through the primary, again producing tens of thousands of volts. Your handheld "stun gun" might work like the old photoflash or ignition circuits. What they are not telling you is that the amount of energy delivered may be very small.

And, as Andy aka mentioned, it is not likely that the advertisement is completely accurate. Do they guarantee that it will immobilize a professional football player?

  • \$\begingroup\$ Good point, I didn't know that such devices exist everywhere :) \$\endgroup\$
    – slippery
    Dec 28, 2013 at 19:11
  • \$\begingroup\$ All you need to do to immobilize a professional football player is to ask them how to keep an idiot in suspense ;) \$\endgroup\$
    – markt
    Dec 28, 2013 at 21:03

Not the answer you're looking for? Browse other questions tagged or ask your own question.