Topic: Model Boat wiring (Read 76867 times)

malcolmfrary · « **Reply #50 on:** August 12, 2014, 09:14:56 am »

Quote

Asked him why and he said "well more volts = more power but I don't know electrickery"He is now using the same packs as the rest of us and his servos have stopped dying

Reading specs for servo ICs a few years ago, several quoted a maximum voltage of 7.5 for the chip. Thats a maximum, not a guide or ambition. Above that, the silicon bits tend to break down, whether conducting or not. If they survive that and work, at a higher voltage, with the same load, they will pass more current. Possibly more than they were designed for, so they respond by melting.
A servo will often quote a maximum voltage of 6, this is often a nominal voltage of a battery, and gives a sort of safety margin for the electronic bits. Its actual voltage in service will (should) be a bit higher, but still within limits. Deliberately connecting a battery of higher voltage drives straight through the safety margin, a 2S LiPo will give a nominal 7.4 volts, a fully charged one will be higher, so no wonder that the DF servos were letting the smoke out. Not that theres much scope for untidy wiring in a DF making a mess of radio reception.

nick_75au · « **Reply #51 on:** August 12, 2014, 09:15:20 am »

I've seen metal on metal servo rods/arms cause interference on 27/29 Mhz radios from the vibration of the pushrod in the actuating arm, so a rotating shaft in a metal tube probably could cause the same issue, in saying that I have never grounded shafts in models.
It probably would be ideal practice though.
Full sized boats we have put a shaft brush connected to the rest of the bonding system, this reduces corrosion and destruction of bearings (through block to shaft stray currents).

Z750Jay · « **Reply #52 on:** August 12, 2014, 09:23:25 am »

The only source of interferance with the DF's I have noted comes when they are at a distance, healed over on a tack and half submerged. It puts the reciever under water. As the 2.4Ghz signal can't penatrate water very well it can be a bit lagy as bit of the digital signal are lost as far as I can work out.

Plastic - RIP · « **Reply #53 on:** August 12, 2014, 03:44:42 pm »

Quote from: nick_75au on August 12, 2014, 09:15:20 am

I've seen metal on metal servo rods/arms cause interference on 27/29 Mhz radios from the vibration of the pushrod in the actuating arm, so a rotating shaft in a metal tube probably could cause the same issue, in saying that I have never grounded shafts in models.
It probably would be ideal practice though.
Full sized boats we have put a shaft brush connected to the rest of the bonding system, this reduces corrosion and destruction of bearings (through block to shaft stray currents).

Are you sure it wasn't the brushed motor inside the servo that was causing the interference?

malcolmfrary · « **Reply #54 on:** August 12, 2014, 06:59:42 pm »

Quote from: nick_75au on August 12, 2014, 09:15:20 am

I've seen metal on metal servo rods/arms cause interference on 27/29 Mhz radios from the vibration of the pushrod in the actuating arm, so a rotating shaft in a metal tube probably could cause the same issue, in saying that I have never grounded shafts in models.
It probably would be ideal practice though.
Full sized boats we have put a shaft brush connected to the rest of the bonding system, this reduces corrosion and destruction of bearings (through block to shaft stray currents).

I've often heard of this, but don't know of any physics that could cause it. Doing a search for RFI and metal to metal rubbing only comes up with model boat sites, so at a guess, something else is having an effect. The same search gives lots of RFI chat, but no mention of metal to metal.
To get into the radio via the aerial, you need something like the radio frequency or a harmonic, say 13MHz (million times per second) for a 27MHz set, and enough power. A motor shaft is unlikely to rotate more than a few thousand times per minute. The servo signals base on 50 per second, so that is a possible entry point, but I am still struggling to see how two bits of metal, disconnected from the wiring, rubbing against each other, are going to generate the kind of energy that will hop into the wiring with enough power to cause problems. A moving shaft rubbing insulation, yes, I can see that, but that is not apparently the problem. It would be nice to have a reasoned explanation rather than accepted folklore.

Plastic - RIP · « **Reply #55 on:** August 12, 2014, 07:11:14 pm »

You'll get 2 main kinds of interference from a brushed motor - the first is the PWM/ESC drive signal will be made of modulated square waves which are constructed of odd-harmonic sine-waves going up to infinity. 27MHz is actually pretty low frequency these days compared to the speed and rise-times of digital signals.

The second is the sparking from the brushes on the armature. Sparks create all the frequencies in the EM-spectrum at once - visible light is part of that spectrum so you see the sparks but the interference is invisible.

KCS · « **Reply #56 on:** September 10, 2014, 09:38:20 pm »

Quote from: Inertia on August 09, 2014, 11:24:47 am

There's a link here to the Model Boats website where you'll find an article which covers just about everything you need to know - and there's no 'electronics' involved http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054

Thank you so much for posting the link to that article. I really enjoy keeping the electrics tidy in my models, but know very little about it. That article answers many of the questions I had.

Cheers

KC

steamboat66 · « **Reply #57 on:** July 11, 2016, 05:19:20 pm »

the stern tube / prop shaft thing is called "the rusty bolt effect". two different metals and /or oxides rubbing together can produce significant RF interference. the speed of rotation is irrelevant, it's the RUBBING that sets it up. ground loops are another easy way to mess up the radio reception.

tizdaz · « **Reply #58 on:** November 19, 2016, 04:46:17 am »

some good tips in this topic, especially for a "newbie" like myself!

Im a fussy git too, i build PC's & when it comes to the wiring it has to be PERFECT! & tidy :) ...and its gunna be the same for my Tug!

RAAArtyGunner · « **Reply #59 on:** November 19, 2016, 05:49:28 am »

Quote from: tizdaz on November 19, 2016, 04:46:17 am

some good tips in this topic, especially for a "newbie" like myself!

Im a fussy git too, i build PC's & when it comes to the wiring it has to be PERFECT! & tidy :) ...and its gunna be the same for my Tug!

Good to see other Gunna's still exist.

tizdaz · « **Reply #60 on:** November 19, 2016, 06:21:43 am »

Paul2407 · « **Reply #61 on:** March 20, 2017, 06:53:00 am »

I've not built a boat for a long time now (until current one) so I haven't got any pics yet of my wiring in the rc boats, but I have got this photo of my 1/8th truggy build and its wiring if it's of any interest to anyone, I know there is a lot more wiring in boats but I will be doing it exactly the same way with the sheathing etc as it makes it look neat and also helps to protect it should it get caught in anything, this car flies it does around 50mph on 4s lipos approx 60+ mph on 6s

Onetenor · « **Reply #62 on:** October 06, 2017, 01:43:24 am »

If you ask the car boys and they'll tell you three .The other two give protection from brush to casing R.F.. They reckon it's caused by chatter of the brushes in the brass carriers. Right or wrong I do not know. It sounds feasible though.I was told this years ago with 27 meg gear so it might be different now. I suppose there is no harm in putting the 3 on though.

Stan · « **Reply #63 on:** March 01, 2018, 11:18:21 am »

HI All just one picture showing the wiring on my 1/200 scale Missouri. I have to agree I like to see tidying wiring.
Second picture from my latest build
Stan.

Pat Matthews · « **Reply #64 on:** November 19, 2019, 04:45:25 pm »

Wonderful!
Seeing the terminal blocks brings up another topic: How to terminate a wire for use in the screw-clamp terminal block?

1. Solid core wire: Just stick it in there and clamp.
2. Stranded core wire: Also OK to stick it in there and clamp... BUT DO NOT SOLDER THE ENDS! Soldering is often done to make a "solid" end for clamping, but it is the opposite... under clamp load, the soft solder relaxes and the joint becomes loose. Lots of fun debugging that issue later on!

The high tech way to do stranded wires is to terminate with a "crimp pin" fitting:
https://www.rcgroups.com/forums/showthread.php?1530964-Wires-to-battery/page2#post40644755

You can find the crimp tool and a box of terminals on ebay and elsewhere for not very much. But these put a solid end on your stranded wire, plus give you a little collar to grab on to.

.

Stan · « **Reply #65 on:** November 19, 2019, 05:28:55 pm »

Sorry guys all my choc block have gone in the bin now using these new connectors. Simple to use strip your cable lift the lever insert cable lower lever job done. The only downside is they all carry the same polarity but you can work out what you need to wire up your project. I have enclosed some pictures. More information if you need it.

Stan.

Pat Matthews · « **Reply #66 on:** November 19, 2019, 06:10:13 pm »

OK then, those do look nice! Series 221 from Wago, can be used as free-standing common connector (replaces a wire nut in an electrical box), or it looks like you have glued them down to the base board? Wago also offer a rail mount clippy thing which could be modified for chassis mounting:

.

Stan · « **Reply #67 on:** November 19, 2019, 06:42:48 pm »

HI Pat fixed using double sided tape.

Stan.

Klunk · « **Reply #68 on:** November 20, 2019, 07:06:52 am »

wire connectors and resistance
https://www.youtube.com/watch?v=Ekh65Jx1Qc0
Interesting viewing

Stan · « **Reply #69 on:** November 20, 2019, 02:48:52 pm »

Just watched the u tube video showing different connectors. There was very little resistance on all the connectors. This will be my second model using the Wago connectors and I have to say choc blocks for me are a thing of the past. The Wago 221 connectors are so easy to use.

Stan.

Pat Matthews · « **Reply #70 on:** November 20, 2019, 04:40:22 pm »

What the video DOESN'T address is the all-too-common old style RC battery connector, often called the Tamiya connector. These are just bad, and do have high resistance. I believe this comes mainly from the tendency of the female sleeve to loosen up, but also from the cheap tin plating used. Under high load, the I2R losses can generate enough heat to melt the plastic housings! And this opened the door for all the alternate pluggable connectors out there, like Deans (ugh) and Powerpoles (yay) and all the rest.

Fastelectrics · « **Reply #71 on:** September 13, 2020, 08:36:46 pm »

With regard to earthing the negative side of the receiver to the prop tube. One thing that has been so far over looked is that the antenna (particularly on 27 and 40MHz) should ideally be a 1/2 wavelength long. This would typically be over 16ft long on 27MHz which would be impractical, so anything we fit to our boats has to be a compromise antenna. On a metallic vehicle we can use a 1/4 antenna with the other 1/4 wave being provided by groundplane created by the vehicle body. If we connect the prop tube to the negative wire of the receiver the lake become our groundplane which increases the effectiveness of the receive antenna. You will probably find that this is unnecessary, and the range provided by your Tx/Rx combination is perfectly adequate for your needs. However, if you want to get the maximum possible range a. prop shaft earth will help.

There are certain advantages when using 2.4GHz. Frequency hopping avoids the effect of interference on spot frequencies and a 1/2 wave antenna is only about 60mm long, which is easy to house within the typical model. Noise sources such as those created by motors and control electronics do not normally extend into the GHz region.

Darren007 · « **Reply #72 on:** March 10, 2024, 07:28:26 am »

I have a large tugboat 51” it has a car
Blower motor and a raboesch 400 bow thruster fitted which will run of a 7.4v pack( I’ve been told that it will not run off the 12v battery), I will be using a 12vla battery and have x2 hobbywing speed controllers the radio is a 2.4 6channel. My question is how do I wire it all up? I’m new to rc boating and don’t want to get anything wrong. Does anyone have a wiring diagram of the same set up as me?

JimG · « **Reply #73 on:** March 10, 2024, 11:55:10 am »

You are already getting this question answered in another thread so no need to piggyback on a 3 1/2 year old thread.
Jim

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Author Topic: Model Boat wiring (Read 76867 times)