Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[Rob47]

Today I noticed an issue with the set up in my 1/72 Leander. Individual esc one red wire removed  left motor on its stick is fine but if I try using right stick, at low revs both props turn with left direction being reversed. Once stic is pushed to higher revs both motors settle down. Esc are mtoronik
So help please
Bob

[Fastelectrics]

Can you provide a photo or drawing of how they are connected?

[HMS Invisible]

https://www.modelboatmayhem.co.uk/forum/index.php/topic,70165.0.html
Apart from the minor detail of a red wire removed from a servo plug, or two with a receiver pack, Rob indicated several boats wired as in the diagram.
Many people do so without a care and some loose escs as a result.
So far he's down two escs.
I've been cautioning in person for as long as I remember. The diagram is a version of one I posted on a forum about fifteen years ago. What prevents a catastrophe  is higher servo lead resistance to that of the black wires to the junction. This connection induces electrical noise on top of the pwm signal from Rx to esc and the current can be enough to fuse a track within the esc.

[dodgy geezer]

I'm  a little confused. If you want to run two motors on two separate  channels  with their own escs, so that one  could go forward while the other was in reverse if you so wanted, how should you do it?

[HMS Invisible]

dodgy geezer, is that a question for me or Rob47?

[chas]

Does the transmitter have a mixer function enabled?

[Graham.W]

Reply #2 and the diagram is an excellent summary of the issues.

The only thing I have to add is that one solution is to run two entirely separate receivers.
There's no reason to stick to just one receiver in a boat and they are quite cheap. One per ESC is fine.

Then you have no issues as it's back to a tidy single ESC and no ground loops :)

[HMS Invisible]

...

The only thing I have to add is that one solution is to run two entirely separate receivers.
There's no reason to stick to just one receiver in a boat and they are quite cheap. One per ESC is fine.
...

Yes two receivers is one of the solutions I'd have included in a list if it was ever asked for.
However, way up at the top of this list, would be a dual esc with a single battery feed.
These Chinese escs are good at ten times the price except you'd be well advised to replace linear becs with the little 50p 3 amp modules if you run 14 volts and higher with a heavy bec load.
https://www.aliexpress.com/item/4001021957126.html
Scroll down for more.

[MikeMcP]

Yes two receivers is one of the solutions I'd have included in a list if it was ever asked for.
However, way up at the top of this list, would be a dual esc with a single battery feed.
These Chinese escs are good at ten times the price except you'd be well advised to replace linear becs with the little 50p 3 amp modules if you run 14 volts and higher with a heavy bec load.
https://www.aliexpress.com/item/4001021957126.html
Scroll down for more.

either way, you MUST ensure that only one BEC is powering the receiver
that suggests to me, that all bar one ESC should have its red wire to the receiver cut


alternatively, if you have enough channels on the receiver, and probably easier to understand,
cut all the red wires and use a separate BEC to power the receiver


please advise if I should be sitting on it instead of talking out of it!


cheers
Mike

[HMS Invisible]

MikeMcP,  Rob47 wouldn't connect both becs, but you wouldn't know before  a forensic search of his past posts or being a Mayhem member for years.
Graham.W , this is not a test. It may improve the signal to noise ratio if people like yourself, technicians, engineers, electricians, Physics teachers, or Arduino/PIC users attach one or two word answers to my list of questions.

1. Refer to the loop_current_3 gif of June 30th.
 Instead of a soldered Y-harness as in the diagram, an elderly club member used alligator clips to connec the second speed control to the first esc's blade connectors at the gel battery. The negative alligator  clip was knocked off. What was the result?

2. Refer to the loop_current_3 gif again.
Would shortening the length of black cable between esc negative to the Y-junction help?

3. What would happen to the proportion of unwanted backdoor current if the esc to the Y-junction was so long (or small in diameter) that it was similar in resistance to the esc to Rx wire?

4. An opto lead completely breaks all three wires from Rx to esc but replaces the pwm signal with an infra-red connection. Could such a lead supplied by Mtroniks, fitted between Rx and one of the two escs, block mutual influence as described by Rob47? (see his words)

5. Could that same device prevent damage from an excessive backdoor current path?

6. Would any protective function be negated by adding a separate bec tapped off the drive battery used by the two escs?

7. If yes to the above, would two opto leads restore protection or noise filtering function?

My photo shows a dual 40amp esc where the second Rx plug only has the channel wire in yellow.
8.  Can it suffer noise or damage in the way two physically separate escs connected at receiver and main battery  could?

As a reminder:

...  left motor on its stick is fine but if I try using right stick, at low revs both props turn with left direction being reversed. Once stic is pushed to higher revs both motors settle down...

[Graham.W]

you MUST ensure that only one BEC is powering the receiver

The beauty of the 'two receiver' method is that each ESC+RX is completely independent, so no stray currents are flowing anywhere.

The same deal with the twin ESC mentioned by 'HMS invisible', the currents are resolved on the ESC itself, and therefore not a 'user issue'.

Any other system is prone to error burning out small signal earths, or at least lowering control pulse S/N as the grounds move about. 

[dodgy geezer]

dodgy geezer, is that a question for me or Rob47?

It was a question for whoever wants to answer it!  I have an interest as I am currently putting a paddler together.and wanted two seperate motor controls, capable of reversing one while powering the other forward. I'm not sure if the tank esc will do this...


I would have hoped that a suitable positioning of diodes might have addressed the problem...

[HMS Invisible]

 Two single escs as pictured will work. However they need an unbreakable Y-junction and short "esc to Y " length to keep current and interference voltage in the negative signal leads to a minimum.
 There are some posts on the dual escs have been made on youtube from robot users. One showed the dual escs required a solder blob to suppress mixing.
 There is no on/off switch. Pwm frequency of the 2×15 amp one is 800 Hz. I have not used Aliexpress before but it seems cheaper than Ebay shops by a long shot.
 The RCG poster suggesting diodes was confused. They won't work wherever he had in mind to put them.

[Colin Bishop]

I have an ACTion P94 in my paddler which gives a number of options (see Component Shop website). It does what it says on the tin but the model doesn’t much like differential paddle speeds and in fact works better with the shafts locked and just under rudder control.

Using the P94 facilities tends to make one side or the other ‘dig in’ and the model to list. Of course other models might respond differently. Although I have not yet tried it, I suspect that the best option would be to have tank steering available but only use it when the model is stopped or going slowly and depend on locked twin throttle control and the rudder for general sailing.
I have commented on this on the MB website.
Colin

[Umi_Ryuzuki]

MikeMcP,  Rob47 wouldn't connect both becs, but you wouldn't know before  a forensic search of his past posts or being a Mayhem member for years.
Graham.W , this is not a test. It may improve the signal to noise ratio if people like yourself, technicians, engineers, electricians, Physics teachers, or Arduino/PIC users attach one or two word answers to my list of questions.

...
4. An opto lead completely breaks all three wires from Rx to esc but replaces the pwm signal with an infra-red connection. Could such a lead supplied by Mtroniks, fitted between Rx and one of the two escs, block mutual influence as described by Rob47? (see his words)

...

I seem to recall a modeler across the pond, Chum?, building an ASD tug, with two mtronik ESC, and was recommended, by Paul@mtroniks, to install an opto isolator to stop interference.

[John W E]

hi there, here is an alternative - a little device which goes between the receiver and the two speed controllers - rudder mixer that used to be sold by Forge Electronics - but, now it is sold by 'scalewarship' . 


here is the link - [size=78%]Rudder mixer (scalewarship.com)[/size]


it is a good little device.   I used the original one that was sold by Alan Bond many moons ago when I built the Forceful tug.   I know it works well on several speed controllers in the Forceful Tug.   I have the old Electronize speed controllers and in another model I use MTroniks speed controllers. 


Part of the reason that a paddle tug/any paddler digs in / leans over is because of the non-feathering paddle wheels.   This I have on good authority from a friend.


I know ACTion also make a stand alone mixer, which I have one of two of.  What I found was that you could easily get one of these ACTion mixers to stop responding; and tie itself in a knot.   I am unsure whether this has been rectified, but I do know the late Dave M, was producing a chip for it. 


Couple of shots of the Forceful paddle tug internals, sadly I havent one of the Alan Bond mixer.


John