AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 30)

Page 30 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
Hall Effect voltage signal
The internal circuitry on the EMS is different depending on what type of sensor is being used.
Note that there are two different inputs on the EMS for crank and cam position. One for a Hall
Effect type pickup. The other for a VR or “mag” pickup.
The EMS-4 crank sensor VR inputs go through a signal conditioning chip on the circuit board
that converts the raw (zero crossing) signal into a clean 0-5V square wave signal as shown
below. The signal conditioning circuit will invert the significant edges of the raw signal. The
consistent edge of the raw signal in the example below is the rising edge. The conditioning
circuit inverts the signal and creates a falling significant edge.