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btlbcc
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Gold
Re: Stun Gun and other devices?
btlbcc   9/26/2013 5:52:18 PM
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I suspect it went away for legal liability reasons.  It's a sort of booby-trap after all, and the law frowns on such.  A little old lady leans on your car, gets zapped and has a heart attack or falls down and knocks her head on the sidewalk...  Not good.

Brooks Lyman

btlbcc
User Rank
Gold
Re: “Oh Voltage, Schmoltage!"
btlbcc   9/26/2013 5:49:20 PM
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Actually, I believe it's required to put "Danger! High Voltage" signs on any piece of industrial equipment using 240VAC (and possibly even 120VAC), and I suspect that such voltages are present in a cell phone base station transmitter.

Brooks Lyman

btlbcc
User Rank
Gold
Re: Sound waves rate the strength of the gun
btlbcc   9/26/2013 5:45:44 PM
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The difference (unless the design has changed) between the Taser and a typical "stun gun" is that the Taser shoots (Springs?  Compressed gas?  Powder?) the two electrodes (sharp needles with fine wires attached) into the victim from a distance, penetrating most clothing and presumably, skin, so that a better and lasting contact is made, while allowing the user to remain our of arm's reach from the victim.  I can't say for sure, but I would imagine that the Taser might use lower voltage/higher current than a stun gun.

While the stun gun may be useful in an encounter with an unarmed attacker, any weapon that extended the attacker's reach could lessen the usefulness of the stun gun.  A better choice might be pepper spray, although in a crowd situation you might have some collateral damage.  On the one hand, I wouldn't want to have to use pepper spray in a crowded subway car, while a stun gun might be just the thing to discourage the pickpocket or purse snatcher.  Conversely, out in the open, the pepper spray might be the weapon of choice.

And, of course, for more serious social encounters, there's always a handgun, if you have a license to carry and the necessary training.  And for most of us, we need to pick one of these and go with it; unlike soldiers, it's not practical for civilians (particularly urbanites) to go about one's business hung about with various weapons, each to be used as the situation requires.

Brooks Lyman

jhankwitz
User Rank
Platinum
Re: Stun Gun and other devices?
jhankwitz   9/26/2013 5:43:38 PM
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I remember that well. We had that system hooked up to my old man's 1951 Cadillac. We used an isolated/insolated chain dangling on the ground. While driving, wind force would keep it from dragging and wearing out, but when stopped, it would lay on the ground. We had to make sure the ignition was 'off' when exiting or entering the car. ZAP!

Critic
User Rank
Platinum
Nice Post, Thanks!
Critic   9/26/2013 4:37:27 PM
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The truth is that you don't need a lot of voltage to shock or kill someone. 

While the calculation in the article is approximately correct for the voltage required to initially break down the spark gap, once the arc starts, the voltage is significantly lower than the inception voltage.  If the stun gun terminals were in contact with human flesh, the voltage would be even lower.

The resistance of a human, over a short distance, if the skin isn't broken, is on the order of a few thousand ohms, up to maybe 100 k ohms.  As little as 10 mA can cause a painful shock, so the required voltage could be as low as (assuming R = 5k ohms) 50 V.  To be sure to shock a high-resistance person, you need about 1 kV. 

So a stun gun needs to produce at least 200 kV (in round numbers) to break down the spark gap, with enough current at a lower voltage to make a hot, noisy arc, and it needs to be able to source at least 10 mA at voltages in the range of 50 V – 1 kV.  I am sure the people who make stun guns have this all figured out, and they have also figured out that the words "high voltage" or high numbers are what scare people.

Your body will only be at 100 kV potential (relative to one the Van de Graaff generator's terminals), when you touch the Van de Graaff generator, if you are not directly across its terminals.  That is, the output current of the Van de Graaff generator flows though your body, but the voltage drop across your body is small compared to the voltage drop though the air between you and the other generator terminal.  Picture yourself being a small resistor in a large divider.  You can safely touch one terminal of a 100-kV source that is capable of high current, as long as you are insulated from the other terminal.

samsuffy
User Rank
Iron
Re: Stun Gun and other devices?
samsuffy   9/26/2013 4:14:29 PM
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To William Kay

When I was a teenager, we would create a shock circuit for cars by using an ignition spark coil powered from the battery through a buzzer salvaged from a doorbell or old car radio. Mount the coil on some convenient place under the car and allow the hot wire from the top dangle to the ground. Anyone toching the car while standing on the ground would get a considerable shock. You could even nose the car up to another one and chart it also. Be sure to include a cutoff switch. We had a lot of fun.

Sam Suffy

Noor Khalsa
User Rank
Iron
Re: Sound waves rate the strength of the gun
Noor Khalsa   9/26/2013 4:09:56 PM
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Does it actually cause fibrillation at the heart, like an AC signal, or clamping (DC)?

I would think that if it caused fibrillation, there would be a lot more deaths from these.

 

Re: disreguarding high voltage signs - There was a local tagger here  who breached a substation barrier and began to spray paint. The subsequent arc flash left him with burns over 60% of his body. But, being young, he clung to life for several more days.

Technophile
User Rank
Bronze
Transient or steady-state?
Technophile   9/26/2013 4:07:34 PM
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While I agree that the voltage claims seem highly exaggerated for sales purposes, I will be a bit of a devil's advocate about the maximum voltage across a spark gap.  Let's state some assumptions:  in atmosphere, clean air, within 1000' of sea-level, 25%..75% RH.  Are you also assuming steady-state conditions or transient?  I would expect ionization of the air across the gap to take some amount of time. 

Critic
User Rank
Platinum
Re: Sound waves rate the strength of the gun
Critic   9/26/2013 3:56:43 PM
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Voltage sells! 

In this instance, 14,000,000 V is the model number, not the voltage.  Read the product description!

William K.
User Rank
Platinum
Stun Gun and other devices?
William K.   9/22/2013 6:31:08 PM
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At one time I heard a radio ad for a system called "Black Max", which was supposed to be ablke to shock attempting car-jackers.That was probably ten years ago.  I thought that was a very good idea, but I have not been able to locate the product. But the question is about how to complete the circuit, since just one terminal can't deliver much of a shock, at least not under normal conditions. And it would not bother me at all to put an attacker who had a gun at some risk, since getting shot is usually quite a bad thing. But 50,000 volts at even just ten milliamps is 500 watts, which is a lot of power to come from any package. But it would probably deliver enough zap to send the bad guys off in search of someebody less well protected. 

But that protection system seems to have just gone away.

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