Warning / Safety Notice:

• This tester is for basic DIY and educational use only.
• It is not a professional-grade tool and should not replace certified NCV testers when working with high voltages.
• Always follow standard electrical safety precautions when handling AC wiring.
• The author is not responsible for accidents, injuries, or misuse of this circuit.
• Do not touch any live wires or objects with the antenna and circuit.

This project is a Non-Contact Voltage (NCV) Tester, designed to detect live AC wires and electronic signals safely without making direct contact.

The circuit is built using three BC547 NPN transistors, which act as a simple amplifier to sense electric fields. When a live wire is nearby, the circuit triggers both a buzzer and an LED indicator, providing audible and visual feedback.

Features:

• Detects live AC wires without direct contact.
• Built with common and easy-to-find BC547 transistors.
• Buzzer + LED give clear indication of live presence.
• Powered by a small 3V battery for portability.
• Antenna input increases sensitivity for better detection.

How it works:

The antenna picks up the electric field around live wires. The 3-transistor amplifier circuit boosts the weak signal, activating the LED and buzzer when live current is detected.

Applications:

• Safe detection of live wires in household circuits. (Only for professionals, read the warning)
• Educational tool for learning transistor amplifiers and sensing circuits.