Controlling servos over long distances

[jackytwoshoes]

I have 2 simple servo controllers which use a rotary potentiometer to control the position of a servo.

I want to have the controllers by my side and the two servos about 20m away in two seperate locations. Can I use some cheap 3-core cable or will I suffer to much loss with that much cable? Do I need to look at radio control?

 

[KMoffett]

Do you want the potentiometers at one end of the cable and the controller/servo at the other end, or the pot/controller at one end and the servos at the other?

Ken

 

[jackytwoshoes]

Thanks for your reply. I'm happy with either- whichever allows me to use the cheapest and longest cables without problems, although ideally the pot/ controllers at one end and the servo at the other.

 

[KMoffett]

1. If the pots are just changing a DC level in the controller, than it would be easiest to have the pot on one end and the controller/servo on that other.
2. If the pots are part of an oscillator circuit in the controllers and have pulsing voltages on them, I would opt for the pot/controller on one end and servo on the other.
3. I did a 100ft CAT5 cable link between a R/C servo drive signal and a computer input. I was monitoring the timing as a function of position of a solar tracker. To assure that I had accurate timing, I used a MIC4427 MOSFET gate driver. I had no signal degradation. I didn't try it without the driver.

Ken

 

[jackytwoshoes]

Thanks for this, the pots are indeed just changing a DC level in the controller and are working great over 100m of CAT 5 cable.

The problem I now face is that when I connect two controllers/servos to the same power supply they are causing the servos to twitch a little. How can I de-couple them?

 

[jackytwoshoes]

Perhaps I should have said, the circuits are currently running form batteries but will eventually be from a wall-wart style mains PSU.

 

[KMoffett]

A schematic or sketch of your setup would help us visualize where your problem might reside.

Ken

 

[jackytwoshoes]

They are off-the-shelf items
http://www.maplin.co.uk/servo-and-controller-board-kit-528801

They use a NE556 timer chip. I'll post a photograph shortly.