Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Electrical interference  (Read 2383 times)

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Electrical interference
« on: August 30, 2011, 12:22:10 PM »

Grrrrr! Cant believe this! For the first time in over 25 years, I've got electrical interference in a model, whether plane, car, heli or boat  >:-o . Not happy!

OK, Im wiring up the 'Dirty Harry' Envoy. Im using a MFA geared motor that has a beige capacitor(?) pre installed across the motor terminals and is running off a 12v SLA. This is wired to an Electronise FR15HX which has 3 frequency settings low, variable and high to supposedly give longer run time or smoother slow speed operation. the esc is about 9 inches away, positioned in front of the motor. The rudder servo is about 4 or 5 inches behind the motor with its lead routed away from the motor and esc ie the opposite side to the boat.

The reciever is about 12 inches from the rudder so the lead is quite long although I have put a loop in it. The reciever is also position on the opposite side of the boat away from the esc. The aerial is routed under the deck forward to the bow.

Now then, when I wire everything up and run the motor, I get intermittent 'twitching' of the rudder. It doesnt matter whether I set the esc to variable or low frequency operation (havent used high as this is described for fast boat which Dirty Harry isnt and not so good for slow running).

So, how do I stop the rudder interference? All motor cables are routed so as not to cause interference to the radio or servo as best as possible. The MFA motor has a supressor so should be ok? I've two of these in Drumbeat and there's not interference (although Im using ACTion esc \ mixer in her  :-)))

I cant shorten the esc or motor cables due to where the esc needs to be positioned as it has a short reciever lead.

HELP!  <:(
Logged

Tug-Kenny

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 7,680
  • Location: Newport. S Wales
Re: Electrical interference
« Reply #1 on: August 30, 2011, 12:33:34 PM »


It does sound like the ESC.  Have you another one you try. ?

ken


Logged
Despite the high cost of living   .......... It remains popular

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #2 on: August 30, 2011, 12:52:21 PM »

It does sound like the ESC.  Have you another one you try. ?

ken




Not that run on 12v except the one in Drumbeat which I dont really want to remove if I can help it.
Logged

nick_75au

  • Guest
Re: Electrical interference
« Reply #3 on: August 30, 2011, 01:02:28 PM »

I would look for moving metal to metal contact, whether the prop shaft, rudder linkage or some other random, a "bond" between metal components will sort that out,, The receiver, esc or motor could be the culprit, or a damaged antenna in either the Rx or Tx. swapping components to a known good one may be worthwhile to trouble shoot. The frequency setting on the ESC will have little effect if the problem is elsewhere.

Cheers
Nick
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #4 on: August 30, 2011, 01:26:02 PM »

Thanks both for your suggestions and I have now sussed it! Hurray!  {-)

When I checked the battery holder, I noticed two of the nimh cells had 'furred' and contaminated some of the contacts. So, got a new battery holder out of the box and installed 4 newly charged cells. installed in the boat and................ still had interference  >:-o Hmmmm.

So, before binning the esc and buying a better make, I  tried the high frequency setting in desparation. Believe it or not, that cured it! No rudder interference at all when motor running at full chat or any other speed. I'd discounted the high frequency setting as the instructions say this is ideal for racing or high speed boats and, instead concentrated on the low and variable settings.

By using the exponential on the transmitter, I can soften the slow start and limit top speed so Dirty Harry doesnt take off like a scalded cat!

However, it still poses the problem, why is there interference from the esc when set to low or variable frequency and how would one stop it affecting the rudder (the motor didnt seem to be affected by the interference).
Logged

ACTion

  • Guest
Re: Electrical interference
« Reply #5 on: August 30, 2011, 01:47:45 PM »

Those MFA geared motors are notoriously "dirty" and really need 0.01uF capacitors between each of the brush terminals and the case, in addition to the one fitted between the brushes. You might also twist together the two wires between the ESC and the motor.
DM
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,529
  • Location: Blackpool, Lancs, UK
Re: Electrical interference
« Reply #6 on: August 30, 2011, 02:48:25 PM »

If its an AM set, the rudder twitching is the prime indicator of interference via the radio, and usually the motor is the handiest source.  The receiver is listening in the long quiet bit between bursts of information, and the first signal that it thinks it sees is passed to channel 1, usually the rudder, so the rudder twitches.  Less of a problem with FM outfits, should not happen at all with 2.4GHz.
As Dave says, increase to the full set of three capacitors, take the opportunity to replace the existing one since they are pennies, and there is nothing to say whether the original is actually working, and no easy way to test it without specialist gear.  Twisting the motor leads as a pair is good too, as is twisting the power leads going to the ESC, since these get the self same current pulses.  Twisting causes the interference coming from each wire to be cancelled by that coming from its mate.  More or less.
Checking the motor for sparks will help - if the brushes/commutator are sparking it could be a sign that either the brushes need bedding in or the commutator needs a clean, or both.  Light brush tension gives the same problem, as does a commutator running out of true.
The higher frequency might give the motor a series of smaller shoves, resulting in less back EMF at the end of each shove, less energy to dissipate, thus less interference.  Thats just a guess, though, as are most things interference related, until you get the actual cure, then it should all be obvious.  Hindsight.
Logged
"With the right tool, you can break anything" - Garfield

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #7 on: August 30, 2011, 02:57:10 PM »

Again, thanks all.

The radio is a qualitee Futaba 40 Mhz FM set which was used in RC cars for racing. So I know the radio wasnt the problem per se.

If I have any further probs, I'll have to add more supression as Dave says although I find soldering three things to one tag ie lead and two separate supressor legs to be a real difficult job. So fingers crossed there's no more issues.  :-))
Logged

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,529
  • Location: Blackpool, Lancs, UK
Re: Electrical interference
« Reply #8 on: August 31, 2011, 09:25:19 AM »

Quote
I find soldering three things to one tag ie lead and two separate supressor legs to be a real difficult job.

The tag usually has a hole in it, usually enough to take two capacitor leads.  Poke through, fold back so that they have a bit of mechanical grip and leave some length poking through.  Use this as the tag for the main wire.  Capacitor leads should be as short as possible from component to tag, but a bit of extra tag helps make life that bit simpler.  If the tag lacks a hole, then it back to a single fold over of the wires so that they will hold in place until the solder has done its work.  Pre-tinning the wires always helps, even if they already look tinned.
Logged
"With the right tool, you can break anything" - Garfield

kiwimodeller

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 615
  • Location: Waihi, New Zealand
Re: Electrical interference
« Reply #9 on: August 31, 2011, 11:46:02 AM »

There is a very good article about suppression on the website of Model Solutions of Canada (http://www.modelsolutions.ca/ ) on the technical pages. Among the solutions not yet mentioned in this post are soldering a lead from the motor case to the propshaft tube and looping the motor and battery leads through Ferrite Beads. I found both of these suggestions very effective when trying to suppress my vintage Taycol motors which make horrific quantities of RF interference. Hope this helps, cheers, ian.
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #10 on: August 31, 2011, 07:21:43 PM »

There is a very good article about suppression on the website of Model Solutions of Canada (http://www.modelsolutions.ca/ ) on the technical pages. Among the solutions not yet mentioned in this post are soldering a lead from the motor case to the propshaft tube and looping the motor and battery leads through Ferrite Beads. I found both of these suggestions very effective when trying to suppress my vintage Taycol motors which make horrific quantities of RF interference. Hope this helps, cheers, ian.

Thank you for the suggestions. setting the esc to high frequency appears to have removed the problem. I've mailed the manufacturer for comments regarding interference when set on low or variable frequency.

If they dont respond(!) I'll give your suggestions a try, especially the ferrite beads.  :-))
Logged

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #11 on: September 02, 2011, 10:03:07 PM »

Well it looks like electronize's customer service is non existent  <*<

Not even an acknowledgement to my query about interference. I find that pretty poor in a manufacturer tbh.
Logged

BarryM

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,689
  • Location: West Lothian
Re: Electrical interference
« Reply #12 on: September 02, 2011, 11:05:32 PM »

That's about par for Electronize, I've found.

Barry M
Logged

dougal99

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 2,909
  • Huntingdon, Cambs, England
  • Location: Huntingdon, England
Re: Electrical interference
« Reply #13 on: September 04, 2011, 03:41:37 PM »

Well it looks like electronize's customer service is non existent  <*<

Not even an acknowledgement to my query about interference. I find that pretty poor in a manufacturer tbh.

So you gave them just about 48 hours. Is that really enough time, especially in the holiday period?


I have no connection whatsoever with the company.
Logged
Don't Assume Check

justboatonic

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,355
  • Location: Thornton Cleveleys
Re: Electrical interference
« Reply #14 on: September 04, 2011, 05:18:13 PM »

So you gave them just about 48 hours. Is that really enough time, especially in the holiday period?


I have no connection whatsoever with the company.

Tuesday, Wednesday, Thursday, Friday. That's 4 full working days and not even an acknowledgement.
Logged
Pages: [1]   Go Up