Digital Servo Noise

[gklimber]

Why do digital servos buzz and jitter? I originally noticed this on a friend's Sharon and asked him about it. He just said it's normal.

I'm setting up a full house ship with all digital servos and they are driving me nuts chattering and buzzing. Makes me nervous.

Why do they do this and just what are they doing? Searching in a tiny dead band??

Agitated,
jer

[D_Ryan]

Jer;

Give this a look: http://www.rcgroups.com/forums/showthread.php?t=358010&highlight=noisy+digital+servos

regards,
Dave

[gklimber]

Thanks. Looks like the dead band is not only tiny, but the servo's very actively seeking it out.

It's all a good thing, but they do bore into one's head. :>)

Cheers,
jer

[Jurgen]

Yes it's kinda stupid to have a nice glider sounding lika crying cat :D
Mine don't do that, maybe that is because of the Multiplex IPD receiver that state "eliminating servo jitter" in the manual. J.

[jtlsf5]

We had George Steiner give a presentation at the SVSS (Sacramento Valley Soaring Society) meeting last month. George is a long time radio guru, and he knows what he is talking about. While I didn't attend, there was an interesting note in our monthly newsletter about George's comments regarding "digital buzz".

This is quoted from our president, Rich Beardsley's lead in column about George's presentation: "I have heard people say that the buzz from the servo is just the “digital buzz”. George explained that it was a mismatch of radio—the radio not being digital but analog and the servo is looking for a much narrower dead band so it buzzes."

A pretty clear message, the higher the resolution of your radio, the less deadband or slop in the centering that a digital servo looks for. The older 512 radios are worse than the more modern 1024 radios, which are worse than the new very high resolution 2.4G systems. You see evidence of this higher resolution (increased sensitivity) from all of the more experienced users that are adopting 2.4.

JT

[BrianSmith]

I told my buddy "Bubba" that noise bothers me too and he says he loves that sound as the very good nice servos are just reminding him that they are there at his beckon call to stay nicely centered and to quickly preform any thing he asks of them.. :D.. Nice answer. Right? Brian

[Robglover]

I told my buddy "Bubba" that noise bothers me too and he says he loves that sound as the very good nice servos are just reminding him that they are there at his beckon call to stay nicely centered and to quickly preform any thing he asks of them.. :D.. Nice answer. Right? Brian

Right on Flyin Brian!

However, now that I've gone to 2048 resolution my servos don't buzz much anymore. :D

You also need to be sure that all surfaces are free to move easily throughout the servo travel range and that all linkages are slop free but free to travel.

Adequate electrical plumbing is also important. Plenty of current carrying capacity to each and every servo, with enough battery to back it up.

I found with 6 digital servos all busily humming along that one standard switch harness with the standard wiring plugged into the receiver does not give me the current carrying capacity that I need. My Picolario was reporting very low voltages during launches and at other times when the servos were loaded up.

Low voltages = more current demand, yet lower voltages, more current, death spiral. No more AA cells in Bubba's planes. More heavy wires.

Planes happy now, do what Bubba asks them to do when Bubba thinks they should do it. :D

Hugs to Iva and Ava from Bubba. Got sardines ready?