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Ir light barrier

Velleman MK120: IR Light Barrier Minikit

Velleman MK120

Velleman MK120 Infrared Light Barrier Electronic MiniKit

The Velleman MK120 IR Light Barrier Kit can be used to set boundaries, warn against burglars, announce visitors, for science projects or to let you know when your pets are getting close to those expensive electronics. This is also a great board for kit-building experimentation and demonstration.

The IR Light Barrier kit consists of an IR (infrared) transmitter module and an IR receiver module with an LED light indicator and buzzer. As long as the IR light beam is detected from the emitter, it will remain silent. When the beam is broken, the LED on the receiver module will light up and the speaker will sound. The sound is similar to that of the door chime of a convenience store.

This is a kit and requires assembly and soldering. When soldering, use a low heat setting with this board. View downloads tab for helpful assembly and use hints. The Velleman MK120 is not recommended for outside use due to the Sun's IR emissions.


  • Great for science projects, detecting intruders and announcing visitors
  • Audible (85 dB) and visible (LED) alert
  • On/Off switch provided

Velleman MK120 User Demonstration Video


Range 3.3 ft to 13 ft
Power Supply
  • Transmitter: 9V DC / 50mA max. battery
  • Receiver: 9V DC / 20mA max. battery
  • 9V battery holder and adapter jack included. 9V batteries sold separately.
  • Transmitter: 2.2 in. x 1.6 in.
  • Receiver: 3.9 in. x 2 in.

Additional Information

Difficulty Level 2


Assembly manual

Info Sheets

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