Hack Remote Car RC

Hi,

I’m trying to Hack RC of a toy car.

The car has only 2 channels, Forward/Backward & Right/Left, controlled by a B502 90deg potentiometer.

I’ve tried to control each channel with a digital potentiometer, but it only control the Forward and the Right commands.

So I’ve measured with DVM the voltage of the RC potentiometer (of the Right\Left channel) on each state (Right\Center\Left) and write it on a scheme that I’ve attached.

Someone told me I should use a SEMICONDUCTOR like this one:
http://il.farnell.com/fairchild-semiconductor/lm358n/op-amp-dual-1mhz-0-1v-us-8dip/dp/2295980

But I can’t figure out how to connect it with all the system… :blush:

Can someone help me please with any idea of how to replace the RC potentiometers so I could control it from the Arduino?

Thanks! :slight_smile:

RightLeftPot.png

How did you connect your digital pots ?
You might want to use MCP4251

Why is your DVM + lead connected to the GND at the top of your drawing ? (why are you listing NEGATIVE voltages ?

You CANNOT apply negative voltage across the pot. You must reverse the polarity and connect the digital pot so the voltage bias is read as a POSITIVE voltage .

Please edit your voltage drawing to indicate which one is FW/BKWD and which is LEFT/RIGHT.
(It shows L/R at the top but there is no mention of F/B in that drawing.)

Someone told me I should use a SEMICONDUCTOR like this one:

So we can assume you have never heard of an op amp ?

Also draw a complete schematic of your arduino interface to the external hardware on a piece of paper and post a photo of it using the “Attachments” button below.

FYI,
Attached is a sketch that cycles 5 digital pots (rheostat type). It may offer some insight into using digital pots. Here is the link to the Playground library
for the MCP4261 (single pot chip). You need the MCP4251 (14-PIN DIP 2-pot chip)

FIVE_DIGITAL_POTS__delay_10.ino (2.84 KB)

Might be easier to get a small 9g servo to turn the pot.

Might be easier to get a small 9g servo to turn the pot.

Post a photo of the pot stem. It might be possible to mate two circular servo horns and use one to attach to the stem and the other screwed onto the servo (upsidedown) with some way to hold the servo body in place. There are a variety of servo couplings available from hobby stores for such applications. (usually it is attaching to some kind of axle or shaft instead of a pot)