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Mains voltage detector

Velleman K7101: Mains Voltage Detector Kit

Velleman K7101

Non Contact Mains Voltage Detector

Use the Velleman K7101 to easily discover where wires are hidden behind your walls. This detector is useful for both discovery of wires and discovery of interruptions as it tells you when voltage is present. Flashing LED indicators on the detector let you know the proximity of the wires, flashing faster the closer you get to the wire. With the K7101, there's no more second guessing or uncertainty with your wall work.

To have an audio alert accompany the LEDs when voltage is present, attach sv4/12-s buzzers in the PCB space provided on the K7101. The buzzers and accommodating box style, the Velleman G407, are both available as separately sold items. The K7101 is a kit and requires soldering. View downloads tab for helpful hints and assembly instructions.


  • Detects mains of conducting cables
  • LED indication with optional buzzer
  • Distance indication


Power Supply 9 V battery - Not Included
Adjustable Detection Distance Max. 3.9 in.
Dimensions 2.2 in. x 2.5 in.

Additional Information

Difficulty Level 1


Assembly instructions
Written multilingual manual explaining how to build the kit

Parts list
English assembly instructions through illustrations, pictures, etc.

Info Sheets

Resistor colour code

Overview of Velleman modules that are equal to D.I.Y Kits
This sheet is useful when you want to know which modules you could find in the do-it-yourself range of Velleman Kits and minikits.

 Warning: this product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to: www.P65Warnings.ca.gov/product