In this blog post, we’ll break down the operating principles of stun guns and the electrical engineering technology behind them in an easy-to-understand and engaging way.
Recent news reports frequently cover cases of sexual assault or murder targeting women walking alone at night. While the world is becoming increasingly dangerous, women cannot simply give up going out late at night and stay indoors all the time. Even if they learn self-defense, when actually faced with a threatening situation, fear and panic often make it difficult to use their skills effectively. And even if they do use them, in most cases, they are easily overpowered by a man’s physical strength. Given these circumstances, it is no surprise that more women are carrying self-defense devices.
When it comes to self-defense devices, the first thing that comes to mind is the “stun gun.” Stun guns are not merely used as self-defense tools; they are also utilized in hospitals to revive patients whose hearts have stopped, and they are widely used as riot control equipment by the police. For example, devices like the Taser are actually used on-site to subdue criminals or dangerous individuals. Given these diverse applications, how exactly do stun guns work?
Broadly speaking, the operating principle of a stun gun involves maintaining a high voltage internally and, the moment it comes into contact with a target through which current can flow, rapidly releasing the stored current to deliver a powerful burst of energy. To put it simply, just as water gushes out instantly when a tiny hole appears in a dam filled with water, a stun gun releases its accumulated voltage all at once. Behind this seemingly simple principle lies the “voltage doubler circuit,” a core component of electrical engineering that plays a crucial role.
The term “voltage doubler circuit” may sound unfamiliar, but it is a device that, as the name suggests, doubles the voltage. This circuit consists of a rectifier and a capacitor; the rectifier converts alternating current (AC) to direct current (DC), while the capacitor stores the electrical energy. Generally, the electricity supplied to homes and appliances is in the form of AC. This AC voltage is converted to DC via the rectifier, then stored in the capacitor and released as high voltage when needed.
To explain this in more detail, a rectifier utilizes the principle of energy conversion between magnetic and electric forces. Magnetic force is the force generated by a magnet, while electric force is the force that allows electrons to flow. Magnetic force manifests as a magnetic field, and electric force manifests as voltage. According to the law of conservation of energy, the total amount of energy remains constant; therefore, if energy decreases on one side, it increases on the other. For example, as the magnetic field decreases, the voltage increases. To understand this process more easily, consider an hourglass. The total amount of sand inside the hourglass remains constant, but as sand pours out on one side, it accumulates on the other. A rectifier operates in a similar way, converting low voltage into high voltage.
The converted voltage is stored in a capacitor. The capacitor acts as the dam mentioned earlier. In other words, the voltage-boosting rectifier circuit is designed to increase the voltage through the rectifier, store it in the capacitor, and then release it when needed. Based on this principle, a stun gun gradually amplifies a low voltage to convert it into a high voltage, stores it, and then instantly releases a strong current the moment it comes into contact with the human body. By repeating this process, a stun gun is capable of generating a peak voltage of approximately 60,000 volts.
We have briefly examined the operating principle of stun guns. Interestingly, stun guns can be constructed relatively simply using only very basic components of electrical engineering. Electrical engineering has essentially developed with the goal of creating “technology useful in everyday life,” and stun guns are also being continuously researched under this objective. For example, since the limited range of stun guns is often cited as a problem in practical use, research is currently underway to develop practical applications in the form of long guns that fire projectiles. For these projectiles to function as stun guns, they must not only be miniaturized but also require more sophisticated technology to ensure that an effective electric shock is delivered regardless of where the projectile strikes the target.
Furthermore, weapons once seen only in comics or movies—such as “guns that fire electricity in a straight line” or “swords made of electricity”—may one day become a reality. Electrical engineering remains a field with vast potential and will continue to evolve as a vital discipline that not only ensures everyday safety and convenience but also lays the foundation for future technologies.
