Inductive Loop Vehicle Detector works by detecting an inductance change in wire loop (coil) that is buried in road. It does that by measuring the frequency of the internal oscillator which powers the mentioned coil. When a metallic object moves over the coil it changes its inductance and that in turn changes the oscillator frequency which is measured by the microcontroller. It is used for vehicle access control at door and barrier controls, for monitoring the occupancy and for vehicle counting in parking garages, for traffic light installations and traffic controllers, for direction and speed detection of vehicle traffic (if dual channel version is used), in car-wash plants, and so on.

This item for sale is a third generation of this device, fully assembled and comes with an enclosure as shown in photos. Documentation for this double stacked PCB version is still not available. Firmware has identical features as published project on project page.

Features:

• Number of operating modes: 4
• Tuning: Automatic
• Detection type: Presence/Pulse
• Presence time: Adjustable in 3 steps
• Pulse duration: 250 ms / 500 ms
• Signal filtering: Adjustable in 2 steps (NORMAL, HIGH)
• Loop inductance: 20 uH – 1000 uH
• Frequency range: 20 kHz – 145 kHz
• Frequency selection: 2 combinations (LOW, HIGH)
• Sensitivity: Maximum 0.0025\% Δf/f, adjustable in 8 steps
• Detection speed: 10 ms by default, adjustable
• Start-up time: ~ 1 second per channel (or longer if frequency is not stable)
• Power supply: 12-40 V DC / 9-28 V AC
• Current consumption: ~ 0.035 A
• Temperature range: -35°C – 120°C
• Sensor protection: Galvanic isolation + gas discharge tube for lightning protection
• Dimensions: 6.5cm x 11.5cm

DIY version with documentation is available here: https://www.elektronika.ba/868/dual-channel-inductive-loop-vehicle-detector/