servo motor: Arduino Starter kit project 5 question


I recently got into Auduino and got my self the starter kit.

I am really enjoying it so far.

There is a question I cannot find the answer thou…

I am on the Mapping potentiometer value to the servo value part.

Question: When I turn the potentiometer (the analog input values from 0-1023), so it’s PWM output value exceeds around 165, it makes a click noise within the servo case then makes a rattling sound which suggest it is unstable. I tried to find some information within the data-sheet references which the book briefly mentioned in earlier on projects but no real luck. I have a few thoughts but no real solid explination.

Is this because the parts are just cheap ones/defect? why does it make a noise after going past digital 165? (the value is which feeds as the angle of teh servo motor)


sketch_jul31a.ino (445 Bytes)

Likely just a side effect of being a cheap hobby servo (mine twitches a little in that same range), but also possibly how the values waver in that range so much the servo is stressing to keep up. Try delaying the writes to it a little.

Hi, Probably you don't have enough 5V current to run the Servo; I often see that with Laptops / Tablets.

Load the code and then plug in an external 9V or more supply and run the Arduino. Works??

Many servos cannot move through a full 180 degrees and yours may be hitting the end-stop. And some of them can move a bit more that 180 degrees.

If you discconnect the servo from everything you can try slowly turning the servo arm with your fingers. If it won't move any further it is at the end-stop.

It is not good for the servo to drive it against the end-stop. You will overload the gears.

It is also possible, but perhaps not likely, that it may go further in the other direction than 0.

You can get more control of the servo when you use servo.writeMicroseconds()


Thank you team for enlightening me.

@INTP I tried increasing the delay and it doesn't seem to be a delay error as it still occurs after I put the delay to even 1000ms. I am assuming its the hardware issue than delay like you suggest.

@terryking228 Yes my UNO is hooked up via USB to my laptop. but I tried hooking the usb to a power point and same problem. I currently don't own a 9V battery but I will give it a shot when I get the chance.

@Robin2 I do feel like the click is some sort of switch but I would be bold to say it is a end stop because it does go on after the click. but you raise a good point of overloading which I shall take into consideration. I must learn more about the servo,writeMicroseconds() before I comment but I will give it a try when I progress and get the opportunity.

Thank you again team.

If the servo is making a click noise before it gets to the end-stop I suspect there is a gear with a damaged tooth.


I encounter that problem too during my novice days :) check the specs of your servo maybe I cant perform full 360 deg or the model can only achieve 180 deg. if you want your servo to turn 360 deg check other model that can turn 360 deg