Anybody Used a Dial Potentiometer as Throttle?

[Acme Anvil Corp]

Hi all,

My latest side project is an electric rail cart to travel on abandoned railways. Imagine a go-kart with flanged wheels to stay on the tracks and a platform for one or two passengers. Most folks power these with a single-cylinder ICE motor from Briggs or Harbor Freight. Mine will use an old 9C hubmotor in a 20-inch wheel I have laying around. Battery, controller, etc., is standard e-bike stuff from my collection of spare parts.

This thing won't have handlebars so I want to use a dial knob as the throttle. The plan is to mount the throttle dial on an old ammo box that will house the battery and controller.

It looks like I can wire the pot to the controller like a standard throttle with 5v pos and neg, and the signal wire will output variable voltage to control the motor speed. Has anybody done this? Would appreciate any advice, especially about the resistance I need to get the pot output to range from about .8 to 4.2 like a normal ebike throttle.

I'm looking at something like the one pictured below.

 

[fill]

No experience in what your attempting whatsoever, but it smells like an idea that could run down a rabbit hole..
do you want a pot with a linear or logarithmic rate /scale of change between limits for example? (linear i think ? but??)

a cheap twist grip throttle with rubber/elastic bands wrapped in the gap to add friction and hold it when twisted open either fitted to a tube welded to the side of your ammo box or perhaps on a stand atop it would work and you could even use an off the shelf brake cut off and lever for an emergency stop option too.

 

[A-DamW]

I'm looking at something like the one pictured below.

That 10k should work fine.
Anything between 5k and 10k should work.
5k is standard for golf carts.

Below 5k and it can draw excessive current, above 10k can be susceptible to noise.

One thing I'd suggest, some kind of kill switch.

Now we need to see pics of your project!

 

[PaPaSteve]

Yes a simple 5K pot can work.
That's what is used on the bike in my profile avatar.

 

[E-HP]

Hi all,

My latest side project is an electric rail cart to travel on abandoned railways. Imagine a go-kart with flanged wheels to stay on the tracks and a platform for one or two passengers. Most folks power these with a single-cylinder ICE motor from Briggs or Harbor Freight. Mine will use an old 9C hubmotor in a 20-inch wheel I have laying around. Battery, controller, etc., is standard e-bike stuff from my collection of spare parts.

This thing won't have handlebars so I want to use a dial knob as the throttle. The plan is to mount the throttle dial on an old ammo box that will house the battery and controller.

It looks like I can wire the pot to the controller like a standard throttle with 5v pos and neg, and the signal wire will output variable voltage to control the motor speed. Has anybody done this? Would appreciate any advice, especially about the resistance I need to get the pot output to range from about .8 to 4.2 like a normal ebike throttle.

I'm looking at something like the one pictured below.

The pic below is from TommyCat’s throttle article. With a pot based throttle, you need the resistors to keep your throttle output from falling below your 0.8v or rising above 4.2v, to stay within the controllers valid range.

Guide to Hall Sensor Throttle operation, testing, and modification. - Electricbike.com Ebike Forum

***** 8-16-2018 Welcome to the Hall Sensor Throttle Thread! If there is something you'd like to add, correct, needs better explanation, or have a question about... feel free to Private Message me. Better yet, open a new thread in the "Trouble Shooting...

electricbike.com

 

[Acme Anvil Corp]

No experience in what your attempting whatsoever, but it smells like an idea that could run down a rabbit hole..
do you want a pot with a linear or logarithmic rate /scale of change between limits for example? (linear i think ? but??)

a cheap twist grip throttle with rubber/elastic bands wrapped in the gap to add friction and hold it when twisted open either fitted to a tube welded to the side of your ammo box or perhaps on a stand atop it would work and you could even use an off the shelf brake cut off and lever for an emergency stop option too.

Hi Fill, I've thought of that as well and may end up going that direction. In fact I think I can remove the return spring on a twist or thumb throttle so it will hold a given speed.

 

[Acme Anvil Corp]

That 10k should work fine.
Anything between 5k and 10k should work.
5k is standard for golf carts.

Below 5k and it can draw excessive current, above 10k can be susceptible to noise.

One thing I'd suggest, some kind of kill switch.

Now we need to see pics of your project!

Kill switch, yes, 100 percent!

 

[Acme Anvil Corp]

The pic below is from TommyCat’s throttle article. With a pot based throttle, you need the resistors to keep your throttle output from falling below your 0.8v or rising above 4.2v, to stay within the controllers valid range.

View attachment 383661

Guide to Hall Sensor Throttle operation, testing, and modification. - Electricbike.com Ebike Forum

***** 8-16-2018 Welcome to the Hall Sensor Throttle Thread! If there is something you'd like to add, correct, needs better explanation, or have a question about... feel free to Private Message me. Better yet, open a new thread in the "Trouble Shooting...

electricbike.com

Thanks for pointing me to TommyCat's thread. E-S is full of gems like this, sometimes the hard part is knowing where to find them! I will make sure to add the resistors.

I guess the first question I should have asked is if anybody knows where I can get a Hall sensor throttle with a dial instead of a thumb or twist mechanism.

 

[RunForTheHills]

Thanks for pointing me to TommyCat's thread. E-S is full of gems like this, sometimes the hard part is knowing where to find them! I will make sure to add the resistors.

I guess the first question I should have asked is if anybody knows where I can get a Hall sensor throttle with a dial instead of a thumb or twist mechanism.

Grin has one, but it is very expensive. Dyol Bidirectional Throttle, Left

 

[TommyCat]

Would appreciate any advice, especially about the resistance I need to get the pot output to range from about .8 to 4.2 like a normal ebike throttle.

Hard to beat a $6 dollar throttle.
And you could do without the resistors by making stops at the required low and high voltage setpoints. Making the rotation a bit less, home to WOT.

This item linked below may be more durable, but would still require the stops, and a knob... Or set it up mechanically like a boat motor throttle, with a kind of lever.



12-Bit Hall Angle Sensor, 0.088° Resolution, 360° Rotation, Durable Full-Circle Measurement,0-5V Output: Amazon.com: Industrial & Scientific

Seen it mentioned as being used in other throttles but have never used one myself. (verify that it will work before ordering)

I also encourage the use of a safety shut off.

For an in depth look at resistances and requirements of a typical controller as far as throttle signal input requirements, see this thread...
Using an On/Off-Momentary Push Button Switch that’s normally open to replace a hall throttle.

Sounds like an interesting project! Looking forward to some pictures.


Regards,
T.C.

 

[E-HP]

Thanks for pointing me to TommyCat's thread. E-S is full of gems like this, sometimes the hard part is knowing where to find them! I will make sure to add the resistors.

I guess the first question I should have asked is if anybody knows where I can get a Hall sensor throttle with a dial instead of a thumb or twist mechanism.

I wonder if a linear pot would be easier to control than a knob. You could cut a slot in the ammo can with an angle grinder, and mount it inside and use a permanent marker to mark different power levels on the can.