Probe A Stun Gun With iMSO-104

The subject of this blog is the structure and operation of an inexpensive, battery powered, hand held stun gun. On EBay the Street Wise Life Guard SWLG2500RB sells for $20, ships with a charging plug, holster, and an instruction manual. The manufacturer makes a claim that this unit is comparable to units that produce 2,500,000 volts at the electrodes, but concedes that actual measurements are difficult to make or verify.

Stun Gun Overview

Stun gun shown with “Armed” indicator illuminated and high power LED activated.

Top view of the Street Wise Life Guard SWLG2500RB - a $20 stun gun.

Oscium’s iMSO-104 measures DC voltage of 3.6V for charging circuit & LED.

Stun Gun with top cover removed to show intact chain of components, from charging plug to LED and electrodes.

Disassembled stun gun showing the battery, high voltage capacitor, LED lens and electrodes.

Break The Stun Gun Into Its Components

This type of stun gun is rather simple compared to others, and is comprised of the following six fundamental components.


The battery cell in this stun gun is comprised of four rechargeable cells, configured into a 3.6V voltage source. Hand held stun guns are typically powered with individual battery cells of up to 9V.


The oscillator circuit, encapsulated in the maroon blob in the above figures, creates a time varying signal from the DC voltage of the battery. The time varying voltage is used in the next stage to build up charge.


A rectifier typically accepts a time varying voltage as an input and converts it into a nearly constant DC voltage at the output. The rectifier in this circuit is used to charge up the high voltage capacitor in the next stage.


The effective size of a stun gun and the measure of it’s power are parameters derived by the high voltage capacitor at its heart. Schematically, the capacitor is stores the accumulated charge from oscillator and rectifier, and delivers charge on demand to the electrodes when the trigger is activasted.


From Wikipedia: An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. In the case of this stun gun, there are two electrodes, an anode and a cathode, or in simpler terms, positive and negative terminals. The terminals of the capacitor are connected directly to these electrodes and put the high voltage charge across the attacker.

VIDEO: Watch The SWLG2500RG Stun Gun

Here are a couple of things to look for in the video clip

  • The red “Armed” LED illuminated when the safety is switched off
  • Removal of the top cover in order to display interior components
  • The high power LED illuminates when the button is pressed
  • A weak, defective electric arc is diverted towards the interior of the stun gun
  • See how the electrodes loosely fit in the plastic molded housing (NOT SOLDERED)
  • Enjoy hearing the ZAP as the stun gun is fired