Please help with power!

Hi I’ve just recieved servo controller. I am a little new for this kind of projects so I have some questions on how I should power up my controller.
so the questions are:

  1. My I use power adaptors with 15V 600mA instead batteries for powering micro controller system?
  2. The voltage of adaptors as usual are nonstable, so if the voltage suddenly becomes BIGGER than recommended will it just burn up my controller or nothing will happen? (My adaptor gives 20V DC is it possible to use?)
  3. How can I control 2 servos at a time? (Project servo arm: 2 servos at the bottom for strong holding, not let the arm just fall down)

Which servo controller do you have exactly?

The short answer to your first two questions is that you must stay within the voltage requirements spelled out in the user guide. For example, if you have the micro serial servo controller your logic supply voltage must AT ALL TIMES be between 5V and 16V. Dropping under 5V may cause your servo controller to reset or behave unexpectedly, and exceeding 16V at any time can destroy the controller. If you have the 16-servo controller you can use a logic supply of between 5.6V and 25V. It will depend on which controller you have. Keep in mind that these are the limits WITHOUT using the VCC=VS jumper. If you make that connection the safe voltage limits are actually much lower. Here are two example configurations of the micro serial servo controller:

If you want to command two servos which are physically connected to perform the same motion together (or mirrored from one another) you can connect them to two different channels and send the same (or mirrored) position commands quickly, or you can split one signal pin and connect it to the signal lines of both servos.

If you need to reverse the direction of one of the servos receiving this split-signal so that they can face each other, you can reverse the servo’s direction of rotation by opening it up, and reversing the motor contacts AND the wires leading to the resistive element of the potentiometer. If physically hacking a servo isn’t something you want to do, you can also purchase a hobby servo reverser (like this one for example), or a servo synchronizer if you want to be really fancy!

I hope that answers your questions, good luck with your project!


Hey Adam thank you very much for your fast reaction.
Sorry I didn’t mention what servo controller I am using, my controller is the same as the picture you have posted. Your information will probably be helpfull for me. And you have reminded me about Vs=Vcc which I could forget.
I was allready thinking about splitting one signal pin and connecting to the signal lines of both servos, but I you gave me exact answer that it is really possible.
And I really didn’t think about servo direction, which is very important for assembling my robotic arm!
After all I will let you know what I’ve done, and what results I got.

Thank you Adam for your full explanation.

Oh Adam I have tested my powering system it was great. Everithing was working properly.
I have powered servo controller with 8-12V approximately and 4.2V servo for servos. Thank you for all.
I used free software at it was also great!!!
Could someone help me with coding I have a little experience but believe me I am quick learner and I’ll get my project finished.
Does anyone know where to get simple free code like Borland pascal and modify it easily for your own application.
My next tasks will be: I want my robotic arm moving itself continiously using computer preprogrmmed code where I could get for free and modify myself easily. I want to make something like this

Any help would be appreciated!


Please take a look at Colin Karpfinger’s sample C# program for an example of how to write your own program to interface with Pololu servo controllers. C# is free, has a SerialPort object that makes it easy to send serial data, and designing your own custom user interface is fairly straightforward.

- Ben

I have a little problems with servo controller. When I plug my servos in to my controller they start to behave unexpectedly, espicially 2 servos which signal lines are connected to one signal pin in order to perform the same motion together. They just start rounding and they don’t recieve commands correctly, sometimes servos don’t react for commands. I don’t know what to do?
May be I should reset it or there are other ways. Please help.

It sounds like you might have a problem with your power setup. What are you using to power your servos? What are you using to send commands to the servo controller?

- Ben

Ben I am using for powering my controller 9-12 DCV power adaptor and for powering servos 4.5DCV battery. I think problems may occur because of discharging battery. Sometimes my battery gives below than 4.5V. If low voltage is a real cause for my problem please let me know. And how can I always power my servos with exact amount of current.
For contolling servos I am using simple soft at because I am not good at programming…
Waiting for reply.
Thank you Ben!

Can you be more specific about your servo power source? Are you using three alkaline batteries in series? Your servo power might be low for your servos, or you might be having a problem due to your control software. You should try sending commands with the Pololu Serial Transmitter and see if you continue to have problems.

I will be out of town for the next five days, so I won’t be able to respond for a while, but perhaps someone can pick this up and help you if you continue to have problems.

- Ben