Jun 01, 2016 - 10:20 AM
The AES Secondary Ignition Probe is a capacitive probe. A capacitive probe responds to electronic fields. Electronic fields are produced by voltage. The higher the voltage, the stronger the electronic field. In an automotive ignition system, there are very high voltages which emit a strong electric field which can often be picked up by a capacitive probe which can produce a representation of the voltage signal on an oscilloscope.
Electronic Field: Plug an extension cord into a wall socket. The wires in the extension cord will have a voltage and there will be an electronic field radiating from the extension cord.
The AES Trigger Pickup on the other hand is an inductive probe. This type of probe is based primarily on a coil and responds to the magnetic field that are produced by current flow (movement of electrons). Think of it this way: The movement of electrons in a wire creates moving rings of a magnetic field around the wire. The moving rings can then push the electrons in a coil which is placed in close proximity to the wire.
Magnetic Field: Plug an extension cord into a wall socket and connect a light and turn it on. Current is now passing through the extension cord and the light. A magnetic field is now radiating around the extension cord wires….and so also is the electronic field.
Why is the AES Secondary Ignition Probe capacitive?
When analyzing secondary ignition we are interested in the voltages. The voltage is best to determine the health of the signal.
Why is the AES Trigger Pickup inductive?
The goal of the AES Trigger Pickup is to provide a clean and reliable signal for triggering an oscilloscope to the occurrence of an ignition event. This is accomplished by passing the induced current through a conditioning circuit to provide a clean voltage pulse for the oscilloscope.