I’m building a project that uses 12 servos. When I enable just one servo, everything is fine, with the sequencer working as expected. But if I enable two or more servos, they all start chattering uncontrollably and drawing a large amount of power. I’m using FEETECH FS90 micro servos at 6V. Thanks for your help.
Hello.
Your description is indicative of a power issue. Could you post details about the power supply you’re using?
Brandon
Hi Brandon,
Thanks for your response. I’m using a large variable DC supply at 2.5 amps to test the servos. With two enabled, one starts fine, then both servos start jiggling uncontrollably, with the current spiking over 1 amp.
The connected but not enabled servos also jiggle a bit. If I enable a few more servos, they jiggle even more. Sometimes I can get them to stop by holding them.
Maybe there’s a problem with the Maestro? It’s new, but maybe I made some mistake in hooking it up initially.
Chris
Your description still sounds like a power issue. Could you try disconnecting all of the servos, then slowly adding them back one at a time until you notice problems? Also, does your power supply have a current limit setting and if so, what do you have it set to?
For reference, we generally recommend choosing a power supply that can handle the combined stall current of your servos. Those servos can each draw upwards of 800mA at 6V (e.g. when stalled or moving quickly from rest), so I would generally expect your 2.5A supply to be able to handle around 3 of them without issues (and more if you’re using acceleration limiting and only under small loads).
Brandon
I’m using a 30 volt/5 amp variable supply. I turned it up to 5 amps at a constant 6 volts and enabled just 5 servos. Sometimes everything works smoothly, other times every servo starts uncontrollably jiggling at power up. Sometimes it powers up fine, but the jiggling begins when the second servo in a sequence is activated. Even the connected but not initialized servos jiggle sometimes. Just to rule it out, I’m going to order another Maestro and see if that helps. The power supply is less than 5 years old, but I’ll also try using NiCad batteries in case the supply has some kind of issue.
It is normal for servos to twitch briefly when power is applied, and the Maestro does not do anything special with the servo power rail (it is just a power bus). If the servos continue jittering when the channel is disabled, you might try monitoring the supply voltage with an oscilloscope to get a better idea of what’s going on.
Have you tried removing them all and then adding them back one at a time as I suggested? Does the jittering still start with only 2 servos connected?
Brandon
Hi Brandon,
Thanks for your help. I got a new Maestro on Saturday, and the result was the same, ruling out an electronics issue. It turns out the problem was mechanical. The servos are waving blades of grass in an art project, but the blades were too heavy. By using lighter wood, the problem went away.
Chris
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