Haltech S4 Hall Effect Sensor - Manual (Page 2)

E.2.3 Hall Effect Sensors
The Haltech hall effect sensor is a two channel device that can be used to trigger the
Haltech range of ECU’s in a wide range of applications.
The most common application is in a direct fire configuration where a synchronisation
event is required. As the Haltech hall effect sensor is dual channel, it can provide this
synchronisation pulse as well as the trigger signal.
The principle behind its operation is quite simple. As a magnet passes the sensor the
output state changes fro m high to low. The orientation of the magnets determines the
output signals from the sensor.
There are two types of hall effect sensors available from Haltech
The S3 Hall Effect Sensor
The S3 sensor which is identified by a black cable gland, operates i n the following
way:
As a south pole passes the sensor face the signal in both the primary (PIN C) and
secondary (PIN D) channels are switched to a low state. As a north pole passes the
sensor a low state will only occur on the primary channel.
Note: magnets should always be mounted in a non ferrous material
such as aluminium, stainless steel or titanium.
Many installers have successfully mounted the rare earth magnets in non
-ferrous
surrounds such as modified aluminium and stainless steel bolts, and ins talled the bolts
into ferrous material.
With these characteristics a direct fire can be set up in the following way:
Using the sensor on the crank
After a suitable mounting location for the sensor has been found the engine should be
positioned at approx imately 75° BTDC on cylinder no.1 compression. The magnet
should now be placed in the aluminium disk with the south pole facing towards the
sensor, making sure the magnet is in line with the sensor when the engine is in this
position. This is now the refer ence point for all the other magnets. The number of
cylinders will determine the number of magnets required and the angle of installation.
The remainder of the magnets to be fitted will all have a north pole facing the sensor.
The adjustment of the air ga p will be determined by the strength of the magnets used.
This should be tested once the wheel assembly has been installed. Checking the
Engine Data page for steady RPM is usually a good indication that the airgap is
acceptable.