e-bike throttles

[cerewa]

It looks like my cyclone e-bike was put out of commission by a little bitty short circuit that was my own fault because I pushed the wires around a little when I plugged the hole to waterproof it. It's ready to go, except that in the mean time the throttle got broken while the bike was sitting under the tarp in front of my house. It works fine if you just hold the throttle together, but that doesn't really work while actually riding the e-bike.

It looks like there is one movable magnet and one stationary position sensor. The position sensor starts near the N pole of the magnet and interprets "n pole" as "off". As it moves to the middle it senses no magnetic force, and goes to middle power. Then the S pole of the magnet moves towards the sensor and the motor goes to full throttle. (I may actually have the "N" and "S" backwards.) If you take the sensor away from the magnet entirely, it goes to middle power.

Before I figured out that taking away the magnet takes the motor to middle power rather than "off", i was thinking it would be great to have a little magnet strapped to my thumb and just use that to control the throttle. (control the throttle without touching... like magic!) It would have the advantage that the motor would quit as soon as I moved my thumb away from the throttle control in order to grab the brakes. Seems like it would also be pretty simple.

So anyway, anybody else know some stuff about how throttles work? Anybody ever built or modified a throttle? Does anything spring to mind about what makes a good throttle or a bad one?

Realistically, I think I'm going to fix my throttle by duct-taping it together. It will have the advantage of making my bike look even uglier and more undesirable to thieves than it already does. (believe me, it's already pretty crazy looking.)

 

[Link]

They're pretty simple. That sensor (hall sensor) is of a similar type used in brushless motors, except analogue instead of digital. It works just like you say it does; it outputs a varying signal that's dependent on the surrounding magnetic field.

The magnet on the thumb thing would be pretty interesting, but you'd have to use a hall sensor that only responded to one pole of the magnet so it doesn't take off when you move your hand away.

Other throttles use a potentiometer in various ways. Typical three wire pot throttles are used as voltage dividers; positive and negative on the ends, signal on the wiper. Moving the wiper from negative to positive varies the signal.

Two wire pot throttles measure the resistance between one end and the wiper and output a signal based on that.

There's also some weird inductive throttle that I no virtually nothing about. I do know that it uses inductance to vary the signal somehow.

Hmm, prolly it works similar to a hall throttle, but moves a ferrous core in and out of a coil of wire. A circuit (either in the throttle or controller. prolly controller) measures the inductance of the thing and outputs a signal. That sound about right?

 

[Trumpet]

Anybody ever built or modified a throttle?

I built a simple resistive force sensitive throttle out of one of these....

Edit - oops wrong link... this is right
http://www.robotshop.ca/home/suppliers/Phidgets/phidgets-force-sensor.html

Gutted the mechanicals of a momentary switch, and mounted both in a plastic box so that the momentary switch bears down on the force sensor pin when pressed. Didn't even have to change the module resistor divider network. Works OK, not as responsive and accurate as the original twist throttle in the kit that I bought, but wanted the brake/gear lever positioning and comfortable grips back.