Digital Servo Interactions

[flyingw]

Jim,

I hope you and your family are well.

I have a setup with an XPS Nano receiver, and three ProModeler micro digital servos.  Two DS100s on elevator and rudder, and one DS150 on ailerons.

With the radio, receiver and servos powered up with a two-cell 6.6v life receiver pack, I adjusted the aileron pushrods.  While removing, turning and then re-installing the kwik links onto the aileron servo horn, I placed slight amounts of turning force on the DS150 aileron servo.  This caused the servo to make some noises which I expected as it held its position against the loads imparted by my fingers.

What I did not expect was that the other two servos also made small jittery movements when the aileron servo was disturbed.

I never noticed this phenomenon before.  Do you think there may be a problem with my setup?

Thank you,

Paul

[XPS]

It could be noise from the servo under load. Plug in a different servo and try stalling it to see the affects of the others and then also see if a different servo is affected the same way as the others when DS150 is stalled.

[flyingw]

I repeated the test using a DS100 servo in place of the DS150 servo and observed no interaction.

Then I repeated the test gain with a standard-sized DS130 servo - also no interaction.

Then I tried the DS150 and two different servos (and a different XPS Nano receiver) - the interaction was back.  So it seems that the interaction happens with the DS150 servo.

I tried using a servo extension cable that included a noise-suppressing toroid ferrite ring, but it made no difference, so I think you're right about it being the power draw of the servo.

The DS150 is a high torque, high speed servo in a small form factor, so I reckon it just draws a lot of power. For the tests I used two different 6.6v life receiver batteries, each proven in larger models with more servos. So I do not think the servo is "browning out" the system, just injecting some kind of noise.

Do you think the Vin and ground rails on the Nano receiver could be filtered using a capacitor?