Optical Distributor

Optical Distributor fitted with an optical pickup assembly with light-emitting-diode (LED) and photo diode. A thine plate attached to the distributor shaft rotates between the LED above the plate and photo diode below the plate. This plate certainest six equally speed slots that rotate directly below the LED and photo diode.

The inner LED and photo diode act as reference pickup. As in Hall Effect pickup system terms the reference pickup in the optical distributor provides a crankshaft position and speed signal to the PCM. When the ignition switch is on . The PCM supply voltage to the optical pickup that cause the LED to emit light. If solid part of the plate is under reference LED, this light does not shine on the photo diode. Under this condition the photo diode does not conduct current and the reference slot move under LED, the light shine on the photo diode and this diode conduct current and the reference voltage signal to PCM is 5v. As a reference move under LED the light shine on the photo diode and this diode conduct current when this action occurs the reference voltage signal to the PCM is 0v.

Wire up the distributor as shown in the diagram. Connect an osilloscope then spin the distributor and abserve the waveform.

Red- 12v

Black- Earth 

Blue- signal out

Position	Voltage
90	11.55
180	0.38
270	11.55
360	0.38

Enplane the difference between Hall Effect, optical and inductive signal.

Hall Effect and induction non contact technology base another principle that for given current flow a pro proportional magnetic field is produce around the current caring conductor. Both technology measures this magnetic field , but with different sensing method.

The Hall Effect and induction use different technology to measure the magnetic field around a current caring conductress. The Hall Effect Sensor is the best suited to DC current and induct sensor to AC current.

In each of the speed sensor above , how does the degrees turned relate to the degrees of crank shaft rotation?

The Hall Effect a chip of semi conductor material carrying a signal current it is exposed to a magnetic field  a small voltage called the Hall voltage is generated between the chip edge at 90 degrees to the path take by the signal current . the optical is 360 degree.