Stun Gun Basics
A stun gun is a device used for self-defense and law enforcement in many countries around the world. It works by dumping an extremely high voltage, low amperage electric current into its victim, causing his muscles to contract and inducing a state of stupor and unconsciousness. Amperage is the measure of how much electricity is flowing through a circuit, while voltage is a measure of how hard the electricity is pushing. High-voltage, low-amperage stun guns are ideal for self-defense because the voltage contains enough "push" to penetrate through clothing and give a painful shock, while the low-amperage makes it unlikely that the victim will be seriously injured or killed by the shock.
The Circuit Board
The most important part of a stun gun is the circuit board. Heavy-duty electronic components designed to carry a lot of voltage without burning out are soldered into a circuit board. The circuit board is soldered to a battery pack, which provides power to the weapon, usually from AA, 9-volt or other commonly available batteries. The stun gun circuit contains an oscillator, a step-up transformer and a capacitor. The oscillator takes energy from the battery and creates a moving electric current, which constantly switches directions. This is called alternating current, or AC. This current then flows into the step-up transformer, which increases its voltage and decreases its amperage. A transformer contains two coils of wire--a primary, which is attached to the power supply and a secondary, which is attached to the rest of the circuit. When current flows through the primary coil, it creates a magnetic field, which produces a current in the secondary coil. If the secondary coil has more turns of wire, it outputs higher voltage and is called a step-up transformer. The step-up transformer in a stun gun charges a capacitor--a small device for storing electric current. There is also a trigger, which switches the whole device on and off.
Safely Mounting the Electronics
High-voltage electricity can easily jump across small open spaces, creating short circuits. To prevent this, the stun gun circuitry is carefully mounted and isolated inside a solid case. Some parts, such as the transformer may be encased in resin to insulate them from other areas of the circuit. The rest is held in the middle of the chassis by screws that keep it out of contact.
Shocking Business
The business end of a stun gun usually has two or four metal spike contacts. On four-contact models, when the trigger is held down and the stun gun is not in contact with someone's body, the capacitor discharges between the middle contacts, making a flash of light and a zapping sound to discourage the target from attacking. When the stun gun is in contact with the victim, the outer contacts discharge the capacitor, sending an electric shock through his body.
Tags: step-up transformer, electric current, circuit board, contact with, secondary coil, stun circuit
