Haltech E8 - Manual (Page 156)

Haltech E11/E8 Instruction Manual
Figure E.3
Trigger Devices
The output of Hall effect, Optical, or Magnetic Inductive (Reluctor) sensors could normally be connected
directly to the input trigger pin of the ECU. Many distributors used in original equipment manufacturer’s
computer controlled ignition systems would be fitted with Hall / Optical triggers. The internal structure of
such distributors is usually configured so that a chopper wheel attached to the distributor shaft passes
through a gap in the sensor. These devices require three connections:
Power (normally +12V)
Ground, and signa;
Trigger signal output .
Assuming that the timing edges conform to the details set out above, a distributor such as this would
connect directly into the ECU. Often these distributors have a rising edge trigger at 70° BTDC.
Many distributors used in electronic ignition systems contain internal components and layouts the same as
the distributor described above, but are fitted with mechanical and/or vacuum advance mechanisms which
are much less effective and flexible than electronic timing as in the ECU. If these mechanisms can be
defeated or removed, and the timing edges set correctly, then they can successfully be used to trigger the
ECU.
A third type of pickup, the magnetic inductive (reluctor) is used in distributors as well as on crank trigger
units. It is possible to use this type of trigger on the ECU using it’s own internal reluctor adapter to convert
the signal into the square wave required to trigger the ECU. The Primary input is used for the main trigger,
and the secondary is used for the Home (Sync. Event).
Note: Any combination of Hall effect, optical or Reluctor type pick-up may be used for the “trigger” (main
ignition event) and “home” (sync. event) inputs. However, Reluctor type pick-ups must be connected to
their respective Reluctor adaptor input.
The onboard Reluctor adaptor actually has two independent channels. One is for the “trigger” signal. The
second is for the “home” signal. Each Reluctor adaptor channel used requires two wire connections.
The magnetic pickup is basically a piece of wire wrapped around a magnetic core and attached to the
sensor face, which is called the pole piece. The physical size and shape of such a pickup can take many
forms. This type of pickup has either two wires (one positive (+), and the other negative (-)), or three wires
with the third being a shield. The wires are sometimes marked as such, but more often than not they are
unmarked. See the Wiring Diagram and any relevant application notes for how to connect up magnetic
pickups.
If you cannot tell which wire is the positive from markings or wire colour, then it would be necessary to
check the signal going into the ECU using an oscilloscope.
When ferrous metal (metal that a magnet will attract) is passed very close to the pole piece, the pickup will
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