I've fitted an Acewell speedo to my locost and I am trying to wire it via a Sailes Marketing transducer which has 3 wires coming out of it, labelled: yellow/green - signal; brown - positive; blue - earth. How do I connect it, as it seems to me that the Acewell has a red and a white wire to go to a hall sensor???

My understanding is with 3 wires it will be a hall sensor and with 2 wires it will be a vr sensor.

When ive played with an Acewell it was a Vr type set up with magnets to glue on for the sensor to read.

I just can't work out where to connect the 3 wires. How does a transducer work?

As a general rule a 2 wire sensor will give you a ac signal and a 3 wire one will give you a 0 to 12v on/off square wave signal.
You should be able to use a pick up from a pushbike on a Acewell, I did.
Steve.

I've sorted it. Sailles Marketing advised me that yellow & green wire gave out hall signal, so connected that to red wire from Acewell, then the other 2 to earth. It works!