RFD900 makes servos jitter

Hi all,I have 3 planes with APM 2.5 units and one set of RFD900 modules.In any plane I choose, I get slight jitter in the servos when I turn on the RFD900 radio.So far I have installed a ferrite bead at the radio, added 0.1uf and 100uf cap at the radio and shielded the wires going to the radio.I also tried running the radio from a different power source to no avail.If I disconnect the tx and rx wires from APM but still have power applied to the radio then the jitter disappears so the noise seems to be coming through these wires.Any other tricks to try? The radio is on a shielded lead about 30cm (12inch) from the APM2.5

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –

Replies

  • Hi, sorry not to read whole article and maybe not answering right, but this is my experience:

    I built my own OpenLRS with 868MHz/1W  modules. So it is somewhat similar to RFD900. Cheap lousy servos get violent jitter when I come by with Tx antenna. Better servos like analog Hitec have this issue reduced and digital servos are immune. Even 433Mhz/100mW modem caused me little jitter in my cheap lousy servos.

    Solution: separate modem from servos and their lines or use digital servos.

    Sometimes I get cheap servo and test by it's jitter if my Tx is working well.

  • I've also had the same issues with the RFD900 & servos; I always have to drop down the power on the air radio to around 20. I'll try the toroid as suggested!

  • Had the same problem recently with a 3DRadio causing jitter in a high speed tail servo.  It was definitely radiated, because if I cup my hand around the antenna, it stopped.  The antenna was near the servo and wiring.

    4-5 wraps of the servo wire through a toroid cured it.  You said you tried ferrite beads, do you mean the clamp over type?  I tried those, and they didn't help.  Only the toroid worked. 

    • I had this problem with a 3DR radio causing the tail servo on a tricopter to twitch (high speed coreless digital servo in an aluminum case).  I moved the 3DR radio from the tail boom to one of the front booms and the problem was fixed.

      Since the RFD900 is so much more powerful, I'm sure the problem is harder to avoid.

  • Hi - I had this same issue with the 3DR 900mhz radio.  Depends on the servo whether or not the servo twitches due to the 900mhz 3DR radio some do - some don't. 

    I found if I soldered a 33pf capacitor inside the servo between the incoming signal lead and ground I could filter out the glitch. 

    • Brian that's interesting. I will give that a go. Maybe time to pull out my oscilloscope. It's 100mhz so it won't see any 915mhz noise but it might give me a clue as to the PWM shape change with/without the capacitor.
      • Same problem in big rf power of rfd, same problem in orange 1w, my servo 2 Bluebird broke in 10 minutes of jittering. I try filter, shilding whith no luck.

        Change servo to analog Hitec and problem solved!

        • I have analog hitec, need to get mine in the air to see if it jitters, will report back in a few days. 

  • Sorry for OOT: any one also experiencing gps glitch when using rfd 900?
  • Are you saying you're shielding the wire between the APM and RFD900? If so, you don't need to really worry too much about that; what you're likely getting is currents induced in servo wires from radiation emitted from the radio's antenna; I've seen this myself when I had an RFD900, with 2 coaxial cables coming out of it to the antennas; those coaxial cables ran parallel near a servo wire (within <10cm) and caused severe servo juttering.

    To fix it, simply move the RFD900 away from any servo leads; 15cm's distance should suffice; also try and have the antenna perpendicular to wherever wires are running, so that the servo wires sit in the middle or at the top/bottom of the antenna's radiation pattern (assuming you're using omnidirectional antennas).

This reply was deleted.

Activity

DIY Robocars via Twitter
RT @TinkerGen_: "The Tinkergen MARK ($199) is my new favorite starter robocar. It’s got everything — computer vision, deep learning, sensor…
yesterday
DIY Robocars via Twitter
yesterday
DIY Robocars via Twitter
RT @roboton_io: Join our FREE Sumo Competition 🤖🏆 👉 https://roboton.io/ranking/vsc2020 #sumo #robot #edtech #competition #games4ed https://t.co/WOx…
Nov 16
DIY Drones via Twitter
First impressions of Tinkergen MARK robocar https://ift.tt/36IeZHc
Nov 16
DIY Robocars via Twitter
Our review of the @TinkerGen_ MARK robocar, which is the best on the market right now https://diyrobocars.com/2020/11/15/first-impressions-of-tinkergen-mark-robocar/ https://t.co/ENIlU5SfZ2
Nov 15
DIY Robocars via Twitter
RT @Ingmar_Stapel: I have now explained the OpenBot project in great detail on my blog with 12 articles step by step. I hope you enjoy read…
Nov 15
DIY Robocars via Twitter
RT @DAVGtech: This is a must attend. Click the link, follow link to read the story, sign up. #chaos2020 #digitalconnection #digitalworld ht…
Nov 15
DIY Robocars via Twitter
RT @a1k0n: Got a new chassis for outdoor races (hobbyking Quantum Vandal) but I totally didn't expect that it might cause problems for my g…
Nov 11
DIY Drones via Twitter
First impressions of the Intel OpenBot https://ift.tt/36qkVV4
Nov 10
DIY Robocars via Twitter
Nov 9
DIY Robocars via Twitter
Excellent use of cardboard instead of 3D printing! https://twitter.com/Ingmar_Stapel/status/1324960595318333441
Nov 7
DIY Robocars via Twitter
RT @chr1sa: We've got a record 50 teams competing in this month's @DIYRobocars @donkey_car virtual AI car race. Starting today at 10:00am…
Nov 7
DIY Robocars via Twitter
Nov 6
DIY Robocars via Twitter
RT @a1k0n: Car's view, using a fisheye camera. The ceiling light tracking algorithm gave me some ideas to improve ConeSLAM, and having grou…
Nov 5
DIY Robocars via Twitter
RT @a1k0n: To get ground truth I measured the rug, found the pixel coordinates of its corners, calibrated my phone camera with my standard…
Nov 5
DIY Robocars via Twitter
RT @a1k0n: @DIYRobocars is back in December, but outside. Time to reinvestigate ConeSLAM! I rigged up a quick and dirty ground-truth captur…
Nov 5
More…