Inside the dist is a coil of wire wrapped around a pole piece that has a small air gap, coil will measure about 150-400 ohms, depending on brand. Called the pick up coil. This is mounted on the plate where the points used to be, it does not move.
On the rotating shaft is the reluctor, which has tips or projections that sweep past the above air gap, distance from the tip is reqd to be an air gap of 0.008" to generate the correct signal strength. Number of rel tips matches the number of cyls.
The movement of the rel tip generates a small AC voltage, a sine wave, that will be millivolts in amplitude at low engine speeds but will increase to a few volts at higher engine rpms. This creates the signal to the box that says 'I want the spark NOW'.
The two wires coming out of the dist are the wires from the p/up coil.
