Intelligent LED Photometer Test Pen Voltage Detector Voltmeter 70-250V Electric Circuit Tester Screwdriver Indicator Tool For Safe Electrical Inspection

The item you uploaded is a classic, low-cost electrical safety tool designed for basic troubleshooting and checking for the presence of AC (Alternating Current) voltage.Key Features and FunctionPrimary Name: Voltage Tester Pen, Test Pen, Mains Tester, or Neon Indicator Screwdriver.Dual Functionality: It serves two purposes:Voltage Detection: Its main job is to safely detect if a circuit, wire, terminal, or appliance is “live” (electrically energized).Screwdriver: The metal tip is often shaped like a small slotted (flathead) screwdriver, allowing for minor adjustments or removal of screws during electrical work.Voltage Range: The label clearly indicates a working range of 70V to 250V AC. This range covers the standard residential and light commercial voltages found globally (e.g., 120V in the US, 220-240V in many other regions).Mechanism (How it Works):The pen contains a small neon indicator bulb and a high-value safety resistor connected in series with the metal tip.To use it, the metal tip is placed on the conductor to be tested (the live wire), and the user’s thumb or finger must touch the metal contact point on the back cap of the pen.This action completes a very weak circuit through the resistor, the neon bulb, the user’s body (acting as a path to ground/earth), and back to the main circuit. The safety resistor ensures that only a tiny, harmless amount of current (typically less than 1 milliampere) passes through the user.Indication: If voltage is present, the tiny current flow causes the neon bulb inside the transparent window to illuminate/glow, providing a visual confirmation that the conductor is live.Construction and DesignTip: A small metal tip, usually shaped like a flathead screwdriver.Resistor & Indicator: Located inside the main body. The high-value resistor is essential for user safety.Handle: Made from fully insulated, transparent, or high-impact plastic to protect the user from direct contact with electricity.Metal Contact Cap: The metal point on the very end of the pen that the user touches to complete the test circuit.Clip: Often includes a pocket clip for easy portability, allowing it to be securely stored in a shirt pocket or tool belt.This tool is a quick and portable safety checker, providing a yes/no indication of voltage. For highly accurate voltage measurements, a digital multimeter is typically used instead.