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I am attempting to rig an RC Car's rear wheels to an arduino.

Initially I attempted to just hook it into the powered digital pins but after MUCH headache I realized I wasn't getting enough current.

SO I decided to use a digital potentiometer instead.

The plan is to hook the 5v from the arduino (which when used by itself runs the wheels so it IS providing enough current) to the bread board.

Then use the potentiometer to control the 5v flow to the wheels.

I for the life of me can't get this hooked up though.

I am using the below potentiometer along with the Arduino Uno R3

enter image description here

The datasheet

enter image description here

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  • \$\begingroup\$ A digital pot is the wrong tool for the job here. \$\endgroup\$
    – Matt Young
    Sep 22, 2013 at 3:03
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    \$\begingroup\$ Why not PWM through a Darlington? \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Sep 22, 2013 at 3:10
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    \$\begingroup\$ The digital pot isn't wrong, but it can't have the current going through it directly: it could control a current source. However, that is going to be wasteful because it amounts to linear regulation. PWM is indeed the efficient way to control the average current to motors or other devices which don't mind being rapidly pulsed. And it is relatively easy to implement since it involves only full on and off behavior of the output device. \$\endgroup\$
    – Kaz
    Sep 22, 2013 at 3:12
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    \$\begingroup\$ instructables.com/id/… \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Sep 22, 2013 at 3:13
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    \$\begingroup\$ Don't forget the diodes. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Sep 22, 2013 at 3:21

2 Answers 2

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Rather than using a digipot to control an analog voltage, consider using PWM to turn a Darlington transistor on and off very quickly. It will be more efficient, use fewer parts, and be cheaper overall.

"Use Arduino with TIP120 transistor to control motors and high power devices"

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You can design a Voltage-Controlled-Current-Source (VCCS). One way to do it is by using op-amps to build a transconductance amplifier, like transimpedance amplifier only the opposite. Here's one type of circuit that can let you do that.

In this Bilateral Current Source circuit, you can make R1 controllable with the potentiometer.

enter image description here

Taken from Texas Instruments App Notes 31

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  • \$\begingroup\$ Note: This answer focuses on the question asked "How to use a digital potentiometer to control current" \$\endgroup\$
    – Iancovici
    Sep 22, 2013 at 17:27

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