Hey, I hope it is OK to post once more to this thread as it is already marked as resolved, I can also open a new one...but since this is sort the the sequel to the stuff already been discussed I thought I might give it a try!

I am having a 5amps power supply set to 5volts so the EZ-B and my servos are getting the specified amount of operating voltage!

My power supply is an old ELC from France, and the EZ-B plus 10 servos are connected, the servos would be Tower Pro SG90 Micro servo 9g.

My movements are smooth and without jittering, but at a certain point the servos are moving erratic, I made some animation using the AutoPositioner in ARC...It seems like every 10th cycle of the animation will get a problem, then it'll go back to normal again! Also at 5Volts I can hear little crackling noises from the EZ-B, why could that be? It does not make these sounds when it runs on 7.4Volts!

What would be the solution to this problem, how would I calculate the amps my servo setup needs to run steady, how about spikes? Should I just try another power supply, or should I try to bump up the voltage? I heard those servos should take up to 7.4volts without a problem!

Let me know how you would takle this beast....

Here is what I suspect is happening and how you can test it out...

When a servo starts to move, it consumes a lot of amps. I suspect that you are seeing are issues when you move 3 or 4 servos at the same time.

Each servo is probably taking about 1.2 amps for a second or so.

Try to start moving 2 servos at the same time and I bet they don't jerk. If you then try to start moving 4 at the same time, I would suspect that they jerk. It would be interesting to know if the sound from the ezb happens when the servos are jerky. I suspect that it is.

Let us know the results.

You could then add two more and try again. At some point, you will see that the current is too much for the supply. 10 servos on 5 amps is too much draw (not enough amps).

You could use super capacitors to limit the issue. These would be like small batteries preventing this jerky action.

Thanks a lot for the info...actually you were right about the noise coming from the EZ-B, it happens when those servos start jerking! Sometimes I guess also when there are a lot of servos attached while those servos are supporting some load, could this also be the case?

Good to know these sparking sounds are know, it was kind of eerie!

I tried out what you advised and found that the lab power supply I am using is already having problems with only one of the heavy duty servos that ship with the developers kit... so I guess I will have to look for another power supply right?

The capacitor idea sounds also interesting...

The thing is that right now I am still sort of fooling around with the setup and I do not have a specific plan on how the final thing should turn out...so my plan was to invest in a power supply once I know what I will build!

It does kind of make no sense though if I cannot really do anything to my robot because it is having seizures every second move...

So what would be your advice on how to power my test model?

Actually giving it a second thought, I guess the capacitor solution would not make too much sense for me right now, with the given space limitations I think there is no room for all the extra wiring and the volume those capacitors would take...I would have to make a new connection between each servo and connecting port on the EZ-B right?

You can jsut add the caps to any analog port on the EZB and it supports all the plugged in devices. There is a discussion around here somewhere with the details.

For alternative power, the developers kit does come with a AA battery adapter. If you use rechargable NiMH batteries (I suggest Panasonic Eneloop) they actually handle the momentary inrush current very well. Even better would be to get a 7.4v LiPo battery and charger. Cheaper than an adequate power supply, but does limit your test time since you will need to recharge the battery when it dies. Even 2 batteries and a charger would be less expensive than a good power supply thought.

Alan

Post 15 of this thread has the super cap mod instructions: https://synthiam.com/Community/Questions/8686&page=2

Alan

Thanks a lot Alan, I will check this as soon as I do have the time!

I was actually looking for a power supply because I tried to power my EZ-B with rechargeable AA batteries but it was really draining them so fast that I thought it will be a mess if I want to get stuff done and I can't because I need to wait for them to charge!

I would not mind to invest in a power supply, but it would be kind of stupid to buy this in such an early testing stage, if there would be something out there that I could use for a long time without needing to change if I work on future project I could go for it though!

The super car mod looks cool, I will check this for sure! Thanks Alan