do not know what i have done wrong powering servo motors, help please!


Sorry for the noob-like question, but I feel like I researched and followed instructions carefully for this extremely simple project, and I now fear I have destroyed either my arduino board, my servo motors...or both.

The project is extremely simple, and involves controlling movement of 2 or 3 servos. I successfully had 1 servo functioning in the required fashion by simply attaching the servo directly to the arduino. To connect a few, however, requires the use of a breadboard. I wired everything up as follows;

I ran the power and earth from a 5v 3amp dc power supply to 2 separate buses on a breadboard. This was done by simply stripping the wire and attaching this to the breadboard. I ran the power and earth from the servo both respectively to the matching buses. From the ground bus I ran a jumper cable to the ground on the arduino. I ran teh signal cable from the servo directly to pin 9 on the arduino board. I powered the arduino board with a 9 volt power supply. when I turned the power on, nothing happened, I waited a few seconds, and turned it all off. Confused, I connected everything back up without the breadboard and separate power supply for the servo. Now, instead of functioning as it was before, the power LED on the arduino is almost non-existant, and the board begins to heat up extremely fast and it gets very hot. The servo does not move at all, but I can hear the sound of it powering it. Also, it began to smell like frying electronics :/ The arduino powers up fine when the servo is not connected to it, both from the USB and from the 9 volt power supply. It still allows a patch to be uploaded to it.

I am not sure what is broken. I am stressing out as this is for a project with a fast approaching deadline. If anybody can offer some advice, I would really appreciate it. Also, apologies if this is not in the right area of the forum.

Please post a picture of your wiring. Sounds to me like you made a short circuit but from the description I don't see the reason for it. Maybe we see more on the picture(s).

I don't know exactly what was wrong with the setup without the breadboard, but powering a single servo from the Arduino is a dodgy proposition and powering multiple servos from it is not going to work. If the Arduino is getting hot, smelling, not working correctly etc then you should switch everything off immediately and not power it up again until you have fixed the problem.

The original circuit you described using the breadboard sounds correct and is the best way to proceed. Since it didn't work, there was probably a fault either with the hardware or software. Without seeing both, it's impossible to be more precise than that.

Note that it's possible to damage the Arduino I/O pins by drawing too much current from them, and this can destroy individual pins while leaving the Arduino as a whole still working. So, if you're in any doubt about whether the Arduino is damaged, check the actual pins you're going to use by a simple blink + LED + resister test to ensure it's working.

Thanx for the responses I really appreciate it...I have solved the problem which was super basic and super dumb...I reversed the polarity and fried 2 servo motors....It seems that the Arduino board is fine. Thanks again.