VD961A - 'MagnaPulse' Free Exit Magnetometer Vehicle Detector

In stock
Our Price £151.68 £126.40 Regular Price £189.60

The VD961A, known as the Magna Sensor, is of a new generation of electronic sensors which do the job of a loop detector, except better and more reliably. The Magna sensor recognizes vehicles by the ferrous content of the car. Unlike ordinary loop detectors, the sensor adjusts for most drainage and access covers.

Magna uses ambient magnetic fields. The sensors zero to the local magnetic conditions on powered up. Sensors must not be within a steel framed building or within 0.5m of an iron man hole cover, drain or large ferrous mass. Magna sensors are designed to be fitted to the centre of the road . Test the location before fixing in the ground. Contacts are volt free.


VD961A is a road sensor set in the centre of a road suitable for opening an automated gate. Exit sensors give a pulse on a N/O isolated contact when the vehicle arrives.

Magnas recognise vehicles by their ferrous content.  All parameters are self setting to suit site conditions. Mounted in the middle of the road below ground level, the direct burial cable, attached to the sensor goes directly to the control panel in a shallow slot.  The 4 wire cable is wired in and self-sets.



With most vehicles, detection will start at approximately the front bumper and end at approximately the rear bumper. Oddly shaped vehicles such as bicycles and trailers may appear shorter to the Mini-Loop than their actual length. For example, some bicycles detect only for a short period of time near the center of the bicycle. Aluminum or fiberglass trailers will likely detect only for a short period of time around the axle and suspension.

These characteristics are very similar to those of a 6-ft. X 6-ft. loop. The primary difference is that the Mini-Loop in itself is only a point rather than a 36 square foot area. This allows detection of closely spaced vehicles. It also places a new limit on maximum vehicle speed to obtain vehicle detection.

1. Position

The sensor is mounted in the road centre clear of moving steelwork. Presence sensors need to be positioned 2m or more from metal gates. Wooden gates have no effect.

We recommend exit sensors are positioned 3m or more from the nearest moving gate part, mainly for driver for convenience.

Test the sensor in position before burying. It can be moved if necessary. It resets on each power up, so can be moved several times.

Placing Magna in a non metallic pipe pre-laid in the road is highly recommended.

2. Fitting

The sensor is fully waterproof. Depth is not critical for operation. When fitting in a drilled hole, the middle should be over 150mm deep with a min cable bend radius of 75mm for stability and protection.

The sensor can be set in any orientation. A hole drilled at an angle is a simple and effective option setting it deep enough to be protected, and reducing cable radius.   A 20mm drill bit is just big enough.

When setting the lead in black top,  use a packer or sand layer as protection against hot pitch sealing. Setting in a sand course below paving is ideal. Poly-pipe is also recommended for fitting in gravel.


3. Running the cable

Run the yellow cable back to the control panel. The Magna wires direct to control PCB. A stable 12Vdc supply is recommended. A yellow marker tag is provided to identify the connections.

6. Connections / Sensitivity

Sensors power wires are red and black, non-polarised, so connected either way around.     16-30Vac or 12-30Vdc

The solid state outputs are only for switching control panel inputs, 100mA maximum.