Speed Sensor rotor.

[Jayneflakes]

Originally Posted by yorkie_chris

Yeah the sensor is a hall effect one. It works by metal in the rotor passing by the sensor which is some semiconductor and swaps between conducting and nonconducting.

Now it makes sense. I did not know that things had moved on so much.
Cheers Chris.

[Sid Squid]

It's called a Hall Effect sensor. Named for Mr Hall, an clever American bloke who worked it out in the late 1800s
Said simply: There are three wires going into the sensor, two supply it with a voltage and the other is the output. There are ferrous metallic pieces in the rotor and as these pass the pickup they cause a change in the sensor's magnetic field which causes a change in the electron flow across the sensor in a phenomenon known as the Lorentz Effect, the upshot of this is that the output wire is fed with pulses and the electronic trickery in the speedo counts these pulses, knowing how many pulses in what time allows you to calculate the speed.

Thank you Mr Hall!

Click here!

[Jayneflakes]

Thanks chaps, I am a little familiar with the Hall Effect and was impressed that it was used on the motorbike. My CG has a geared cog that drives a cable operated needle gauge, that is somewhat less impressive. I am just pleased that the bike is working again, so want to go for a ride once I pass my test.