On the old "Star Trek" series, Captain Kirk and his crew
never left the ship without their trusty phasers. One of the
coolest things about these weapons was the "stun" setting.
Unless things were completely out of control (as they
frequently were), the Enterprise crew always stunned their
adversaries, rendering them temporarily unconscious, rather
than killing them.
We're still a ways off from this futuristic weaponry, but
millions of police officers, soldiers and ordinary citizens do
carry real-life stun weapons to protect against personal
attacks. Like the fictional phasers of "Star Trek," these
devices are designed to temporarily incapacitate a person
without doing any long-term damage.
In this edition of HowStuffWorks,
we'll find out how stun guns and Taser guns pull
off this remarkable feat. While these weapons are by no means
infallible, they can save lives in certain situations.
A Shock to the System We tend to think of
electricity as a harmful force to our bodies. If lightning
strikes you or you stick your finger in an electrical outlet,
the current can maim or even kill you. But in smaller doses,
electricity is harmless. In fact, it is one of the most
essential elements in your body. You need electricity to do
just about anything.
When you want to make a sandwich, for example, your brain sends
electricity down a nerve cell, toward
the muscles in your arm. The electrical signal tells
the nerve cell to release a neurotransmitter, a
communication chemical, to the muscle cells. This tells the muscles to
contract or expand in just the right way to put your sandwich
together. When you pick up the sandwich, the sensitive nerve
cells in your hand send an electrical message to the brain,
telling you what the sandwich feels like. When you bite into
it, your mouth sends signals to your brain to tell you how it
There are a wide range of stun weapons in use
today. The three most popular devices, the standard handheld
stun gun, the Taser gun and the liquid stun gun, all have
particular advantages and
In this way, the different parts of your body use
electricity to communicate with one another. This is
actually a lot like a telephone
system or the
Internet. Specific patterns of electricity are transmitted
over lines to deliver recognizable messages.
Down for the
effectiveness varies depending on the particular gun
model, the attacker's body size and his determination.
It also depends on how long you keep the gun on the
If you use the gun for half a second, a painful jolt
will startle the attacker. If you zap him for one or two
seconds, he should experience muscle spasms and become
dazed. And if you zap him for more than three seconds,
he will become unbalanced and disoriented and may lose
muscle control. Determined attackers with a certain
physiology may keep coming despite any shock.
The basic idea of a stun gun is to disrupt this
communication system. Stun guns generate a high-voltage,
low-amperage electrical charge. In simple terms, this
means that the charge has a lot of pressure behind it,
but not that much intensity. When you press the stun
gun against an attacker and hold the trigger, the charge
passes into the attacker's body. Since it has a fairly high
voltage, the charge will pass through heavy clothing and skin.
But at around 3 milliamps, the charge is not intense enough to
damage the attacker's body unless it is applied for extended
periods of time.
It does dump a lot of confusing information into the
attacker's nervous system, however. This causes a couple of
things to happen:
The charge combines with the electrical signals from the
attacker's brain. This is like running an outside current
into a phone line: The original signal is mixed in with
random noise, making it very difficult to decipher any
messages. When these lines of communication go down, the
attacker has a very hard time telling his muscles to move,
and he may become confused and unbalanced. He is partially
The current may be generated with a pulse
frequency that mimics the body's own electrical signals.
In this case, the current will tell the attacker's muscles
to do a great deal of work in a short amount of time. But
the signal doesn't direct the work toward any particular
movement. The work doesn't do anything but deplete the
attacker's energy reserves, leaving him too weak to move
At its most basic, this is all there is to incapacitating a
person with a stun gun -- you apply electricity to a person's
muscles and nerves. And since there are muscles and nerves all
over the body, it doesn't particularly matter where you hit an
In the next section, we'll look at the main types of stun
guns and see how they dump this charge into a person's body.
Standard Stun Gun Conventional stun guns
have a fairly simple design. They are about the size of a
flashlight, and they work on ordinary 9-volt batteries.
The batteries supply electricity to a circuit consisting of
various electrical components. The circuitry includes multiple
components that boost the voltage in the circuit, typically to
between 20,000 and 150,000 volts, and reduce the amperage. It
also includes a oscillator, a component that fluctuates
current to produce a specific pulse pattern of electricity.
This current charges a capacitor.
The capacitor builds up a charge, and releases it to the
electrodes, the "business end" of the circuit.
The electrodes are simply two plates of conducting metal
positioned in the circuit with a gap between them. Since the
electrodes are positioned along the circuit, they have a high
voltage difference between them. If you fill this gap with a
conductor (say, the attacker's body), the electrical
pulses will try to move from one electrode the other, dumping
electricity into the attacker's nervous system.
Cattle prods are
similar to stun guns in design -- they apply an
electrical current across two electrodes -- but they
serve a completely different function. A stun gun uses
an electrical charge to incapacitate someone, while a
cattle prod applies a charge to get a person or animal
moving. A cattle prod only causes pain, it does not
significantly affect the muscles and nervous system of
These two devices differ mainly in voltage.
The voltage in a stun gun is high enough to dump
electricity into the entire body. The lower voltage in a
cattle prod only shocks someone at the point of contact.
These days, most stun-gun models have two pairs of
electrodes: an inner pair and an outer pair. The outer pair,
the charge electrodes, are spaced a good distance
apart, so current will only flow if you insert an outside
conductor. If the current can't flow across these electrodes,
it flows to the inner pair, the test electrodes. These
electrodes are close enough that the electric current can leap
between them. The moving current ionizes the air
particles in the gap, producing a visible spark and crackling
noise. This display is mainly intended as a deterrent: An
attacker sees and hears the electricity and knows you're
armed. Some stun guns rely on the element of surprise, rather
than warning. These models are disguised as umbrellas,
flashlights or other everyday objects so you can catch an
attacker off guard.
These sorts of stun guns are popular with ordinary citizens
because they are small, easy-to-use, and legal in most areas.
Police and military forces, on the other hand, typically use
more complex stun-gun designs, with larger ranges. In the next
couple of sections, we'll look at some of these sophisticated
Flying Tasers One popular variation on the
conventional stun-gun design is the Taser gun. Taser
guns work the same basic way as ordinary stun guns, except the
two charge electrodes aren't permanently joined to the
housing. Instead, they are positioned at the ends of long
conductive wires, attached to the gun's electrical circuit.
Pulling the trigger breaks open a compressed gas
cartridge inside the gun. The expanding gas builds
pressure behind the electrodes, launching them through the
air, the attached wires trailing behind. (This is the same
basic firing mechanism as in a BB
The electrodes are affixed with small barbs so that
they will grab onto an attacker's clothing. When the
electrodes are attached, the current travels down the wires
into the attacker, stunning him in the same way as a
conventional stun gun.
The main advantage of this design is that you can stun
attackers from a greater distance (typically 15 to 20
feet / 4 to 6 meters). The disadvantage is that you only get
one shot -- you have to wind up and re-pack the
electrode wires, as well as load a new gas cartridge, each
time you fire. Most Taser models also have ordinary stun-gun
electrodes, in case the Taser electrodes miss the target.
Some Taser guns have a built in shooter-identification
system. When a police officer fires the Taser electrodes,
the gun releases dozens of confetti-sized identification tags.
These tags tell investigators which gun was fired, at what
location. Some Taser guns also have a computer system that
records the time and of every shot.
Tasers are only one way to conduct current over greater
distances. In the next section, we'll look a relatively new
long-range stun weapon that doesn't use any wires at all.
The companies that
make stun guns specify that the weapons should be used
conservatively, only for self-defense or incapacitating
an unruly person. Unfortunately, stun guns are commonly
used as torture devices in many parts of the world.
International reports that a number of governments
routinely use stun weapons to extract confessions from
political prisoners. These officials know that
electrical torture leaves less evidence than many other
methods. The shock from a stun weapon is extremely
painful, but it doesn't leave an obvious wound. So,
while stun guns might be relatively safe weapons when
used correctly, they can be quite dangerous in the wrong
Liquid Charge One of the newer stun weapons
is the liquid stun gun. These devices work the same way
as Taser guns except they use a liquid stream to conduct
electricity rather than extended wires.
The gun is hooked up to a tank of highly conductive
liquid, typically a mixture of water, salt and various
other conductive elements. When you pull the trigger,
electrical current travels from the gun, through the liquid
stream, to the attacker.
In addition to
incapacitating violent citizens out on the street, stun
technology is also used to subdue criminals behind bars.
There are prisons around the world that use stun-belt
devices to keep their inmates in line, and to intimidate
Stun belts are basically stun guns that are already
attached to potential offenders. Corrections officers
carry a remote-control unit that operates the stun
weapon. If an inmate becomes unruly, the officers
activate the belt, which applies a high-voltage charge
to the inmate's kidneys.
While the inmate is stunned, officers may drag him back
to his cell.
guns have a longer firing range than Taser guns, and you can
shoot them many times in succession. They are generally more
cumbersome than Taser guns, however, because you need to cart
the conductive liquid around. High-powered guns work with
vehicle-mounted water cannons, while portable models typically
include a water tank backpack. Many portable units use the
same sort of water pumping system as Super
Soaker squirt guns.
Today, stun weaponry is a rapidly growing field of
invention. Law enforcement and military forces need non-lethal
weapons to subdue angry mobs without racking up civilian
casualties. Many citizens who are concerned for their safety
but aren't comfortable with firearms are seeking out reliable
"safe weapons." As this technology advances, the prospect of
Star Trek-type phasers doesn't seem so far-fetched. The teleporter,
however, is another story...