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### Author Topic: Replacing two analog POTs in mobility scooter bot  (Read 541 times)

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#### tgibbons

• Beginner
• Posts: 2
##### Replacing two analog POTs in mobility scooter bot
« on: July 05, 2014, 10:17:27 PM »
I am trying to turn a mobility scooter into a base for a robot. I would like to use the scooter's motor controller and simply replace the scooter's two analog POTs with a digital POT that I could control from a PC or Arduino.

There are two analog POTs in the circuit.

•   The max speed POT sets the maximum speed of the scooter. This is a 20 Ω POT on a simple dial.
• The throttle POT is a 4.5 Ω  POT with a spring dial.  The default value is 2.2 Ω  and pressure on the throttle makes the scooter move forward and backwards.

Here is a photo of the circuit components

As best I can determine, here is the circuit diagram

Unfortunately my grasp of analog circuits is limited by the 30 years since I last worked with them... So, two questions:

First, could someone help me understand how these two POTs work together to control the scooter's speed and direction?

Second, how would I replace these two analog POTs with a digital POT which I could control from a PC/Arduino?

#### Tommy

• Full Member
• Posts: 117
##### Re: Replacing two analog POTs in mobility scooter bot
« Reply #1 on: July 07, 2014, 08:27:35 PM »
Quote
First, could someone help me understand how these two POTs work together to control the scooter's speed and direction?

Second, how would I replace these two analog POTs with a digital POT which I could control from a PC/Arduino?

tgibbons, as to your first question, it would seem you have a single axis drive(one motor), I would guess your analog voltage to be 0 to 5v with 2.5v as stop, 1v would be full reverse and 4v as full forwards,I would guess if the voltage goes over 4v or under 1v the drive will go into fault mode.

as to your second question there are a number of option for PC control.
http://www.phidgets.com/products.php?product_id=1002
http://labjack.com/u3
http://www.usdigital.com/products/interfaces/pc/usb/USB4

I have used both the labjack and usdigtial unit with good results

Tommy

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• Posts: 2