Flutter on servos when ESC plugged in

[Len Morris 2Participant @lenmorris2]

Just connected all the RC gear in Resurgam. Everthying works a treat – ish! Three servo's, rudder, hydroplanes and battery shift. They all work spot on. When the ESC is plugged in the motor works fine but at anything other than full throttle the other three servos have a flutter on them.

Can't really get the ESC any further away from the RX as the boats not that big. Wonder if it's a shielding problem?

Len

[Len Morris 2Participant @lenmorris2]

[Dave MilbournParticipant @davemilbourn48782]

Len
I've been right through your Resurgam thread and in none of the pictures where the motor is shown can I see any RFI suppressors. You MUST fit a 0.1uf ceramic disc capacitor across the two motor terminals as the very minimum amount of motor RFI suppression. Two extra 0.01uF ceramic caps between the terminals and the motor case (or the brass mount in the case of your model) would be better. Keep all capacitor leads as short as possible. Twist together the two leads between the motor and the ESC – it doesn't have to be tightly wound. Make sure that the receiver aerial is as far away from all other wiring as possible.
Fingers crossed!
DM

[Len Morris 2Participant @lenmorris2]

Hi Dave,

Thanks for that. Just been a bit lazy uploading pics. Motor is fitted with an Action Electronics RFI kit. The soldering is good and the connections checked with my meter. Just to stop anything moving the bits were then epoxyed in place and then painted with matt black paint.

Not the best job in the world but I think it's serviceable.

Having taken all this afternoon trying to analyse the problem, 'flutter' is the wrong word. It's slight movement on the servos when the ESC is activated. My R/C kit is the Multiplex Cockpit system which has no end of channel mixing functions for planes and helicopters. Suspect this might be where the problem lies. Now reading the programming book!

Len

[Dave MilbournParticipant @davemilbourn48782]

Len
A bit late now but when fitting these capacitors you should keep the legs on them as short as you can, or they will act as perfect little aerials for the unwanted RF. From the photos it looks rather like you've left the legs all the same length as supplied! The small axial one should go in a dead straight line between the two motor terminals and the other disc ceramics from the terminals to a point on the edge of the case as close to the terminal as possible. In a metal hull any RFI will be 'bounced around' inside so good suppression is even more crucial.
You may have channel cross-talk problems but there ought to be an option whereby you can select a "new model" memory with all of the channels set to neutral and all the mixers switched off. That is a very nice radio but it's so slanted towards aeroplanes that you almost have to fight it when programming it!
Fingers still crossed.
Dave M

[Geoff SleathParticipant @geoffsleath41411]

Len, I assume you're using a Multiplex receiver as well? They are superb receivers on 35Mhz and presumably on 40Mhz too. You shouldn't get any motor interference with them. As Dave says, the leads on your ceramic disc capacitors are a bit long. They need to as short as possible to be fully effective. If you're on 2.4Ghz then they are even more solid. By using the esc I assume you mean when you open the throttle to start the motor.

I use an older Multiplex transmitter (a 3030) and they are excellent pieces of kit especially when using receivers with digital signal processing (DSP or IPD) as the Mux receivers do.

Geoff

[Len Morris 2Participant @lenmorris2]

Hi Dave and Geoff,

The problem is not solved but it's gone away! Here's the full story. The ESC was the last thing to be installed. In the mean time to test the other three servos, the RX was powered up by its own power supply. When the ESC was installed I decided not to use the BEC feature initially and cut the central red wire. In my head, I was trying to keep things simple to start with – I can see and charge my own RX battery but can't see a BEC! This morning I ditched the separate supply battery reconnected the BEC and the world is now beautiful again!

No idea why (and at this stage I'm too bothered about having an idea – it works – end of – the bathtub is filling up as I type)!

Yes the kit is all Multiplex on 40 MHz. Reassuring that you think it's good kit as I was't sure when I bought it (just followed the advice of the model shop) and Dave, you are dead right about programming it. Spent all last night going through the manual. My brain hurts!

Thank you both for your help.

Len.

[Malcolm FraryParticipant @malcolmfrary95515]

When the motor is running, the battery is under substantial load. Anything in the battery or wiring that causes the voltage supplied to the servos will cause them to think they need to re-position themselves. Their position sensing relies on them getting a very stable voltage, if it varies, they "think" that they are not in the correct position and correct it. Of course, a servo driving to correct its position is another momentary load…….

[Len Morris 2Participant @lenmorris2]

Hi Malcolm,

Thanks for that. It's because of a possible voltage drop due to the motor running that I initially powered the RX and servos with their own separate supply. In theory they should have been totally independent of the motor demand but not so. They all moved slightly when using the ESC. With the BEC connected all the problems went away.

Len

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