A stun gun is a weapon that incapacitates a person without causing any long-term damage. An ordinary citizen can carry it along to protect himself against personal attacks. The concept of stun guns was put forward years back by a science fiction 'Star Trek'.
It is a weapon that gives an idea of how our futuristic weaponry will be. Today, millions of people, including military personnel to normal citizens, carry stun guns as a weapon of self-protection.
Basically, the human body has electric energy as one of the most essential elements. Our brain and nervous system uses electric signals to communicate and transfer messages to various parts of the body.
If you want to hold a ball in your hand, your brain sends electrical signals to the muscles in your arm via the nerve cells. The muscle cell in the hand then reacts according to the signal received. Almost all activities performed by our body include exchange of electric signals between various parts of the body and the brain.
In order to keep our body functioning properly, we need this communication to be carried out without interruption. If any unwanted noise signal is added to the original signals that the nerve system and brain are using for communication, then confusion is created, and functioning of the body gets affected. A stun gun works exactly on the same principle.
If we pass an electric signal (not having much intensity that can damage a person's nervous system) in someone's body, this will interrupt the communication system of the body; confusion will be created in his/her communication system, as the charge combines with the electrical signals from the person's brain.
When a noise gets added to the original signal in the body, it becomes almost impossible to decode the signal by the nerve system at the receiving end and do exactly you want to. This causes a nerve system failure, and the individual gets paralyzed for some time.
Electricity can be harmful for the human body, and can even be fatal, but only when a very high intensity charge is passed through the body for an extended period of time.
When we use a stun gun against an attacker, it passes an electric charge in the attacker's body with fairly high voltage, which passes through the clothes and skin. The gun uses a charge that is not intense enough (around 3 milliamps) to harm the nervous system of the attacker.
It does, however, add confusing information to the attacker's nervous system, and it becomes unbalanced, as the nervous system cannot decode the information properly. Ultimately, the attacker gets paralyzed, temporarily.
Today, there are different types available in market, generated with various techniques incorporated to make them effective. Effectiveness varies depending on the size of attacker, time period you keep the stun gun in contact with the body of the attacker, type and strength of the gun, and what intensity charge that can be input in the attacker's body.
Stun guns are about the size of a flashlight, and they work on ordinary 9-volt batteries. The electricity to the circuit containing various components is provided by the batteries, which convert this electric current into high voltage and low intensity charge, used to paralyze an attacker for a short period.
The circuitry inside includes multiple transformers, components that boost the voltage in the circuit, typically to between 20,000 and 150,000 volts, and reduce the amperage. It also includes an 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, which are at the end, and are brought in contact with the body of the attacker. As the gun makes the contact, the high voltage charge, which is inside the circuitry, gets shifted to his body, as the electric circuit gets completed. And the charge is passed to the attacker's body.