controlling servos with potentiometer

Hi everyone,
I'de like to control servos with a potentiometer from eight meters away.
the normal setup with pot and servo works fine.However i tried using a long three wire audio signal cable and i did't get any results. Guess the distance between pot and controller/ servo is just to big ( resistance to high probably) does anyone know a way around this problem, or should i try radio control instead.
preferably i'de like to use cables if possible.
any suggestions? thanks

step4step:
However i tried using a long three wire audio signal cable and i did't get any results.

Between pot and Arduino, or between Arduino and servo.

Extending the pot with shielded wire should not be a problem.

How are you powering the servo. I hope not from Arduino's 5volt pin.
Leo..

thanks for reply.
yes eight meters between pot and servo.arduino mega is close to the servo.
yes i was powering directly from the arduino 5v pin

Stereo audio cable should work fine. I assume your pot is 10k linear (10kB).
Use shield as ground, one core as 5volt, and the other core from wiper (center pot pin) to the analogue pin.
You really should use separate power for servos.
Leo..

I'de like to control servos with a potentiometer from eight meters away.

You mean like an R/C transmitter and receiver?

Thanks Leo,
I'll give it another try.yes its a 10 k pot.
I used the cable the way you said.
I'll hook up the servo externally.
thanks i'll post the result

p.s yes awol i meant r/c transmitter and receiver.....i'll try the long cable first though....

step4step:
i did't get any results.

What does that actually mean?

step4step:
Guess the distance between pot and controller/ servo is just to big ( resistance to high probably)

"Guess" and "probably" are not good words to use in electronics: that's why we have meters.

Have you measured the resistance of the wire?

Have you measured the voltage across far ends of the 5V and ground wires to and compared them to the actual voltage of the 5V pin to ground?

Have you measured the voltage on the Arduino end of the wiper with the pot turned fully to the high voltage side?

tdg.jpg

step4step:
I'll hook up the servo externally.

Don't forget the ground wire from the servo and its supply to the Arduino:

tdg.jpg

Hi,
Put a 0.1uF capacitor between the Arduino analog input and gnd at the Arduino, this will help with any noise pickup.

Tom... :slight_smile:

Thinks for your input everyone.
its true: "i guess" really should't get any recognition.However I'm a newbe and i don't own any meters yet.

I did't get any results means: no visual results.servo did't move in any way.

doing an analog read with the pot and long cable to see if the cable is ok

Hi,
Post your servo code.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom... :slight_smile:

hi Tom thanks for pointing that out.

I'm running the sketches on a mega 2560

to find out if my cable was actually sending signals a first used an Analog Input output sketch from the library. this involved dimming a led, with a pot. first the standard setup with short jumper wires.it worked.
also the serial monitor gave me figures from 0-255,as expected.
then i used the same sketch, but this time with the long cable.Dimming did't work and no values on the serial monitor.so i got a new cable.this time a telephone cable.Dimming the pot worked.
The serial monitor however only showed values only from 0-55,which i can't explain.

But still a successful test as controlling the led was possible.

Next step was using this cable and inclining it in the Servo Knob setup.
I used the Servo knob sketch from the example list in The IDE.
However i took the advice on powering the servo externally.grounded everything correctly.and everything worked. the servo can be controlled from 0-to not quite 180 degrees.Hardly any jitter
The cable I'm using is only three meters long.Next step is getting a three phase cable with eight meters and also taking the 0,1 uF capacitor between analog input and ground arduino on board.

sketch and diagram will also be posted

so far so good,thanks

Hi,
Measure the Voltage at the input pin.

Measure the voltage across the outer terminals of the pot at the end of the lead as you sweep the pot.
Measure the voltage between the gnd end of the pot to the wiper as you sweep the control.

It sounds like yo need heavier wire in your extension lead.

Are you sure the pot is 10K?

Tom... :slight_smile:

thanks I'll check that..