Linear FM139 Free Exit Probe Vehicle Sensor
The Linear FM139 is a hands-free exit wand vehicle sensor with a 50 ft. (15.3 m) cable, designed for automatic gate operation in residential, agricultural, and commercial applications.
Overview
The Linear FM139 Free Exit Probe detects moving vehicles using electromagnetic sensing technology, triggering an automatic gate operator to open without any driver interaction. It serves as a practical alternative to loop detector systems, installing in significantly less time and eliminating the risk of drive-over damage. The FM139 is suitable for residential, agricultural, and commercial gate applications.
Key Features
- Hands-free activation: Automatically opens the gate when a vehicle approaches
- Electromagnetic vehicle-in-motion detection — senses shifts in the Earth's magnetic field caused by moving vehicles
- Adjustable detection radius: Potentiometer board adjusts sensitivity from 3–12 ft.
- Relay latch time: 2 seconds
- Low power draw: 1.5 mA, suitable for solar-powered setups
- Noise rejection: Designed to filter 50/60 Hz line noise near power lines
- Compatible with both single and dual gate systems
- No drive-over loops to wear out or fail
Specifications
- Cable Length: 50 ft. (15.3 m)
- Input Voltage: 8–32 VAC or 8–26 VDC
- Detection Radius: 3–12 ft. (adjustable)
- Relay Latch Time: 2 seconds
- Power Consumption: 1.5 mA
- Probe Dimensions: 1.75" (44.5 mm) diameter x 16.75" (425.4 mm) length
Important Note
The FM139 is not intended as a safety device. Because stationary metal objects can occasionally trigger activation, it is not recommended for areas where children are frequently present.
The Linear FM139 is a reliable, installer-friendly solution for secure, hands-free gate exits with minimal installation time.