eZee Cadence Throttle

[tony18m2001]

I posted this question last month on the eZee FAQ forum, but I realise that these are supposed to be posted on the main forum and only moved later, so hence this re-posting.
Does anybody have details of the signals used on the Cadence throttle? Mine has has lost its return spring and end stop due to damage when the bike fell over, followed by epoxy potting compound getting into the inside and jamming it. I've found that reverse rotation of the throttle control gives a low power setting which is very useful to limit power useage with my current Li-ion battery problems. I'd like to experiment with a replacement having buttons or similar giving low, medium and high power.

Tony

 

[Ian]

Tony, the device used in the throttle is a hall effect sensor which gives a voltage output proportional to the magnetic field from the magnet located in the rotating grip.

Such devices typically have a voltage output range from about 10% to 90% of their supply voltage when subjected to a magnetic field ranging from their maximum negative to maximum positive values. In practice that would mean an output of close to zero with the south pole of a magnet close to the sensor rising to about half the supply voltage as the sensor is moved to the centre of the magnet and to almost full supply voltage when the sensor reaches the north pole of the magnet.

Put simply, the controller requires a linear voltage input from the throttle which could be esily obtained from resistive dividers from the hall effect sensor positive supply. An alternative would be to simply provide a variable resistor, this being what Ezee did on some models, putting it in a tin box and calling it the EAF control.

 

[flecc]

I've toyed with the idea of a variable resistor, but the reliability of them is often suspect, especially with constant continuous action which they aren't generally designed for.

I think the best solution is what I built for my amplifier in place of a normal volume control.

It's a single pole 12 way make-before-break rotary switch with a sub-miniature resistor chain across the connections. That's a very reliable method giving good repeatable performance, and it has the advantage that the resistor values in the chain can be tailored to give exactly the response curve required for smooth linear control.

The snag is the mechanical aspect. The throttle would need a toothed ring driving a cog on the potentiometer shaft, then a suitable waterproof housing over the rotary switch.

Quite a of work to achieve, but the resulting throttle action could be perfect.
.