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Author Topic: OK so what am i doing wrong???  (Read 15457 times)

andygh

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Re: OK so what am i doing wrong???
« Reply #25 on: August 18, 2008, 01:10:26 AM »

Looks like one I got off ebay for about 20 from Hong Kong, mine works OK'ish but I'd try a different type before giving up
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FullLeatherJacket

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Re: OK so what am i doing wrong???
« Reply #26 on: August 18, 2008, 08:34:55 AM »

There are some cheap ex-Hong Kong speed controllers which have absolutely no dead-band at all i.e. unless your Tx is transmitting a neutral signal at exactly 1.5ms then the ESC will just sit and do nothing.
If you have a throttle stick with a ratchet then you're onto a hiding to nothing to try to find an exact neutral. If that is  the case then try using the rudder (steering) stick to test this thing instead, as it has a spring-centred action and is more likely to be near the 1.5ms mark at rest. Also make sure that the trim lever is set exactly in the centre. If you don't have access to an oscilloscope then you'd need some other means of detecting and displaying the transmitted pulse. I have further details if required.
If that doesn't work then take the offending items back to the model shop and see if they will replace them of refund your money. Good luck! Finally, buy a different make of ESC from a reputable UK manufacturer.
I'm afraid we don't yet make one suitable for a 700BB Turbo on 12 or 14.4 volts.............

BTW Barry Park, there's nothing "stupid" about a regime which requires you to switch on the Tx first and off last. If nothing else, a model with a live electric motor and a receiver which is open to any spurious signals is a dangerous thing to handle.

You can suit yourself, mate, but I value my fingers.

FLJ
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RantandRave

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Re: OK so what am i doing wrong???
« Reply #27 on: August 18, 2008, 08:54:42 AM »


I was fighting a speed controller with a similar problem a little while ago, turned out I had the speed controller plug
in the receiver the wrong way round (ie 180o). When all plugged up, does the rudder work? If so the
speed controller is working and providing the BEC voltage and ther is something wrong with the setup procedure
on the speed controller.
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barry park

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Re: OK so what am i doing wrong???
« Reply #28 on: August 18, 2008, 09:53:14 AM »

Quote
BTW Barry Park, there's nothing "stupid" about a regime which requires you to switch on the Tx first and off last. If nothing else, a model with a live electric motor and a receiver which is open to any spurious signals is a dangerous thing to handle.

You can suit yourself, mate, but I value my fingers.

Such a regime is completely redundant. In the era of the microcontroller it is possible for a speed controller to.....
1 be completely immune to spurious output from receivers.
2 suppress the motor at switch on.
3 actually have a startup procedure option (disabled on default reset)
4 be used to reliably detect an R/C transmitter on YOUR receiver frequency.
WhiskyFrank's esc appears not to manage 2 .
 The remaining weakness where spurious immunity ESC can be operated by a second party transmitter on same frequency is shared by the one without that ability. It can also have feature 3.

I have been told by a kit supplier (who bought a batch of hundreds esc's requiring startup routine each time they were switched on) that the esc's startup procedure was the cause most customer gripes to helpline. He decided against supplying it in his kits.....flogged them on Ebay.
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DickyD

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Re: OK so what am i doing wrong???
« Reply #29 on: August 18, 2008, 10:15:14 AM »

OK dickyD........just try taking your electric flight model out for a spin after checking the pack is fully charged (6 volt) O0 

OK Stavros
Quote
2x 1.2v equalls 6v so times 2 equals 12v
.....I think not
Quote
When they are newly charged they show more or less 7v ish each
  slightly more than 14 (not 12).

You may find some speed controllers and servos will work with a 6 volt receiver supply but not a 5 cell Ni-mH pack or 4 new Duracell's......just an example where accuracy counts.
OK barry park, first off my boats dont fly and secondly two of them run on 5 cell NimH packs very successfully thankyou.
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John W E

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Re: OK so what am i doing wrong???
« Reply #30 on: August 18, 2008, 11:22:15 AM »

Hi there WhiskyFrank

I wonder if this is the speed controller with the following specifications; that you are using


Specifications 
Dimensions  54.8mm x 40mm x 14.7mm 
Working Voltage  6 - 12V 
BEC Current  5V/3A 
Internal Resistance  0.0076mΩ 
Continuous Output Current  110A (Forward)
40A (Backward) 
Cable Type  16 AWG (Battery & Motor) 
Cable Length  140mm (Battery & Motor)
450mm (Receiver) 
Input Battery Types  NiCd/ Nimh/ Li-po battery 
Recommend Model  Ship / Car 

- - - -

This looks similar to the speed controller which you have (to me anyway) -one thing which does spring to mind, are you using the Futaba Mini 3/4 channel receiver?   I cannot remember the model number of the receiver just now; however, not so long ago, we had a lot of problems which were mentioned by other members of this Forum, using this miniature receiver to drive Electronize 30 amp speed controllers.

I wonder if this could be a similar problem which you are experiencing?    I wonder if you have access to another RX?  preferably of a 6 channel model?    Or, a totally different radio set-up e.g. HiTec to test the speed controller out with that?

Let us know what is happening?  It may just be a simple solution - you may have your speed controller signal plug around the wrong way.  O0

aye
John e
bluebird



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whiskeyfrank

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Re: OK so what am i doing wrong???
« Reply #31 on: August 18, 2008, 05:44:33 PM »

thats the one i have in the last photo.

I dont have access to any other radio set other than th 2 channel futaba set up i have now.

Im using a 2 channel standrad futaba receiver. The plus is in the right way.

Im giving up on these esc's as it seems to be the problem, the instructions have not set up procedure just switch the tx on first.

Is there an esc that can be reccomended?? Ideally that would work with the set up i have.

Thanks

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barriew

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Re: OK so what am i doing wrong???
« Reply #32 on: August 18, 2008, 07:10:20 PM »


Is there an esc that can be reccomended?? Ideally that would work with the set up i have.


As FLJ has ruled himself out of this {-), then the other two to consider are Electronize and Mtroniks.

Barrie
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John W E

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Re: OK so what am i doing wrong???
« Reply #33 on: August 18, 2008, 07:15:09 PM »

hi there

Before we discuss speed controllers , we really need to know what model we are dealing with.   Basically, I think we are dealing with a speedboat here?   but, what size of boat etc., this would be helpful before we delve into what speed controllers.

Be careful with using Electronize - will discuss this further when we have a bit more detail.   Electronize are very expensive for it not to work with your radio set.

aye
john e

bluebirdy
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DickyD

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Re: OK so what am i doing wrong???
« Reply #34 on: August 18, 2008, 07:29:46 PM »

I use Overlander 50amp speed controller Discharge: 50A forward/20A reverse. Plug in and go, no set up needed.

Its simplicity itself just plug it in.

I have four, no trouble at all.

Idiot proof, which is why I use them. ;)

A Model World normally do them at a good price.

http://www.amodelworld.co.uk/
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barry park

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Re: OK so what am i doing wrong???
« Reply #35 on: August 18, 2008, 08:17:37 PM »

 
Quote
This looks similar to the speed controller which you have (to me anyway) -one thing which does spring to mind, are you using the Futaba Mini 3/4 channel receiver?   I cannot remember the model number of the receiver just now; however, not so long ago, we had a lot of problems which were mentioned by other members of this Forum, using this miniature receiver to drive Electronize 30 amp speed controllers.

I wonder if this could be a similar problem which you are experiencing?    I wonder if you have access to another RX?  preferably of a 6 channel model?    Or, a totally different radio set-up e.g. HiTec to test the speed controller out with that? 


You are referring to this thread http://www.modelboatmayhem.co.uk/forum/index.php?topic=3622.0
BarrieW''s post in that thread diagnosed that the ESC was not compatible with TTL servo signals. (The 2.5 volt PWM pulses on white)
That was a huge clanger on behalf of the esc supplier.
The cure is to ensure the receiver supply is not too high i.e. use 5 volt BEC.  CMOS inputs will then recognise 2.5 volts as a "high"
WhiskyFrank cannot have that problem because he is using the esc 5 volt BEC
Quote
You may find some speed controllers and servos will work with a 6 volt receiver supply but not a 5 cell Ni-mH pack or 4 new Duracell's......just an example where accuracy counts. 
I refer to my bit on TTL /CMOS voltage threshold compatibility.


The same incompatibility problem occurs when you use Fleet and Acoms servos with Futaba receivers.
Nothing to do with PCM as Futaba PWM receivers have used 2.5 v signals for many years. Old Macgregor and Simprop receivers had TTL chips in them and only put out 2.1 volt pulses on white wire.



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DickyD

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Re: OK so what am i doing wrong???
« Reply #36 on: August 18, 2008, 08:36:27 PM »

Hi barry park I hope you are open to a bit of constructive critisism.
Whilst we can appreciate that you must have extensive electronic knowledge, probably some degree or other I feel I should point out that the majority of us haven't.
Whilst your postings are very impressive I think you will find that the majority of us have not got a clue what you are on about and if we had you would not have had to do the posting in the first place
Could you possibly remember in your future postings that the majority of us are laymen not experts.
Check out bluebird's and FLJ's posting and you will see what I mean, them we can understand. O0.
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Martin [Admin]

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Re: OK so what am i doing wrong???
« Reply #37 on: August 18, 2008, 08:49:38 PM »

Hi whiskeyfrank,

Does the rudder servo work?

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OMK

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Re: OK so what am i doing wrong???
« Reply #38 on: August 18, 2008, 10:17:21 PM »

If you don't have access to an oscilloscope then you'd need some other means of detecting and displaying the transmitted pulse....

...such as one of Action's P59 Servo Tester units (the 21-digit LED display will show you the exact servo pulse from the Rx -- no need for a 'scope).
However, I'd put my money on the fact that most of today's ESCs rely on a lower signal pulse voltage - especially the microcontroller-based ESCs (re: that TTL/CMOS thing which has already been mentioned).
In the good old days, when the ZN409 chip was King, just about every R/C receiver would deliver a signal pulse which was pretty much on par to the voltage of the Rx battery (i.e: 4.8 volts or 6.0 volts). But these days (especially now that 2.4GHz is upon us), a lot of receivers are only pumping out something in the order of a 2 or 3-volt signal.... which makes any ancillary units pretty much redundant.
But there is an easy work-around to this problem.

WhiskeyFrank, I know absolutely nothing at all about your particular ESC - I'm not familiar with that one at all. But would you mind helping me out with a little experiment here?....
Grab yourself a grok of the attached image. What this circuit does is to take the signal from your Rx, then boost the pulse to that which the ancillary units can hear. This is about as simple as it gets.
Are you okay with a soldering iron? Would you be up to putting one of these units together?
Failing that, I could bung one together for you. At least we would all then know if my theory is good - or if your ESC has indeed gone blooie.

A tad more info at the top of this page....... http://www.pm.keirle.com/RCGlowplug/glowplug.htm
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John W E

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Re: OK so what am i doing wrong???
« Reply #39 on: August 19, 2008, 11:30:19 AM »

Hi all

PMK cheers for this circuit, I am going to build it right now - to see if it will rectify the problem between a miniature Futaba RX and the Electronize 30 amp speed controller - will let you know how I get on with it.

Richard - wor Dicky....what some people on the Forum want to understand is that 90% of model boaters - the most sophisticated electrical appliance they have for modelling; is a cheap handheld multi-meter - either digital or analogue and all they may use it for is to make sure that the batteries they have - have some life in them.

That is all they wish to know about electronics - hey that is no bad thing.

They wish to spend more time sailing their models - than they do worrying about electronics and how the electronics work.   (I am excluding meself in this) cos I dont spend that much time sailing now - do I Dicky.....

aye
john
bluebird
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barry park

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Re: OK so what am i doing wrong???
« Reply #40 on: August 19, 2008, 02:18:31 PM »

Bluebird,
While you are trying esc and the miniature Futaba RX on the bench ,do me a favour too.
Does it work without the adapter with 4 alkaline batteries ?
Does it work without the adapter with 4 flattish 1.2 nicads at ~ 4.8 to 5.2 volts ?
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OMK

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Re: OK so what am i doing wrong???
« Reply #41 on: August 19, 2008, 02:49:10 PM »

Hi once again, Bluebird. I just logged in and see that you posted your reply about 3 hrs ago. Not sure if that would have given you enough time to build and test that circuit yet, but just for the record, I can tell you that you should have no problem with it running from a Futaba Tx.
Although, whether it will work with you Electronize ESC is another matter, because you might run into another problem regarding the unit being compatible with the polarity of the pulse signal (whether it be high shift or low shift). If this is the case, then this too is easily rectified. All you need is a single transistor and a couple resistors to reverse the pulse polarity. If you have no luck with the booster circuit, then don't junk your ESC until you've tried shifting the signal polarity.

Waiting to see how you got on..................
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John W E

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Re: OK so what am i doing wrong???
« Reply #42 on: August 19, 2008, 03:42:37 PM »

yikes.......things are not turning out right YET.....

BE BACK
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barry park

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Re: OK so what am i doing wrong???
« Reply #43 on: August 19, 2008, 03:45:01 PM »

Pulse repetition rates ..................look away DickyD {-)

1960's 1 channel 27AM Macgregor RC set for yacht rudders ( 4 wires on servo plug)
servo pulse period 11 millisecond ,pulse height 2.2 volts

1970's 4 channel 27AM Futaba M-series RC set for yacht rudders
servo pulse period 13 millisecond ,pulse height 2.2 volts

1980's RC set
pulse height 2.5 volts
servo pulse period 20 millisecond

1990's 8 channel Futaba
servo pulse frequency ~50 Hz for PWM
pulse height 2.5 volts

1990's 16 Channel PCM
some sets up to 100 (according to my buddy)
pulse height 2.5 volts




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John W E

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Re: OK so what am i doing wrong???
« Reply #44 on: August 19, 2008, 04:52:32 PM »

hI THERE one and all and PMK

finished the little project and had a trial with it ...  ;)

it sort of does what it says on the tin, the only problem I am having at the moment is - it repositions the neutrals on the TX stick - will have to sort this out when we can get use of an oscilloscope to set up the signal properly.

Yes, it definitely does drive an Electronize 30 ampers -  I have included a few pics....I did a quick trial with the batteries, 4.8 would not (without the signal booster) work - 6 volt was exactly the same.  More trials will be done in the near future.

Nippy little thing to build for anyone who does want to built it - one thing I have found out mind you...me eyes aint what they used to be  :D :D :D 8)

aye
john
bluebird
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barry park

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Re: OK so what am i doing wrong???
« Reply #45 on: August 19, 2008, 05:32:20 PM »

Thanks Bluebird !

PMK, Can you elaborate on this?
Quote
compatible with the polarity of the pulse signal (whether it be high shift or low shift).

I don't know what you mean. I've never encountered anything other than 0.9 - 2 millisec positive servo pulses.

I have,however, seen than term applied to servo signals meaning 1.5 +/-  0.5 millisecond and changing servo rotation by inverting the signal length around the 1.50 milisecond neutral.
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whiskeyfrank

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Re: OK so what am i doing wrong???
« Reply #46 on: August 19, 2008, 09:15:19 PM »

Thanks guys but im really lost now on this as im mechanically minded not electrinically.

And yes the rudder servo works fine.

How about a seasprint or jeti 600?? as an option
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OMK

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Re: OK so what am i doing wrong???
« Reply #47 on: August 19, 2008, 09:27:51 PM »

Bluebird,

First of all, nice photos. Nice work.
Secondly, I'm not sure why that circuit should be repositioning your stick neutrals. All it should do is boost the amplitude of the pulse signal - nothing else. So I'm taking a wild guess that maybe the pots on your gimbals are slightly out of alignment. The obvious way to tell if that's happening is by hooking up your Tx to the oscilloscope. I would offer to loan you my 'scope but I reckon 'twould cost and arm and a leg to get it to you.
Although, there is an alternative solution.......
I'm sending you my P59 servo tester (check the ACTion website for the low-down). With it you'll be able to see exactly where your gimblals are in relation to the servo signal. The LED display will tell you when your pots are precisely aligned. (Don't thank me - send a bottle of grape juice to FLJ instead).
On the other hand, you're more than welcome to send your Tx this way. I have my 'scope here now - no problem to check it over for you. But in all honesty it's much more fun to dabble with the P59. That way you get to align the pots yourself.... you'll wonder how you ever managed without.

http://www.pm.keirle.com/P59/P59.htm
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OMK

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Re: OK so what am i doing wrong???
« Reply #48 on: August 19, 2008, 09:40:15 PM »

Whiskeyfrank:

Apologies for hijacking your thread here - I've been wandering slightly off topic to your original post.
For what it's worth, please feel free to send your ESC this way for a quick once-over on the bench. I won't cost you a penny more than the return postage.
Likewise, if you feel that you want to take the route of buying a new one, then may I suggest that you point your browser here...

http://www.dawnmist.demon.co.uk/rcm.htm

Good luck.
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OMK

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Re: OK so what am i doing wrong???
« Reply #49 on: August 19, 2008, 10:36:41 PM »

PMK, Can you elaborate on this?

I'll try. But first off, I don't think we've had the pleasure. In which case, hello there.

Signal shift:
Imagine that you're looking at a standard 20mS PPM frame rate on an oscilloscope. When the signal is at zero volts is when the trace on the screen corresponds with one of the horizontal lines on the graticule (usually center of the screen). When the pulse signal comes along, the trace will either deflect UP from the zero reference point (positive shift) or down (negative shift).
It's no biggie. It's just a poncy way of stating how the signal is referenced from zero V.
My understanding is that Futaba have always employed a negative-going shift on all their encoders - they still are. Whereas some manufactures use a positive-going shift.... which would explain why some receivers do not work with some transmitters.

Regarding your penultimate post, it's interesting to see that even those early encoders from the '60s and '70 all had a frame rate of anything other than the usual 20mS. I had one just the other day that weighed in @ 17mS... then another at 26mS... and another @ some other frame rate that I can't even remember. Each one different.
But let's assume for a moment that the actual frame rate is not the issue. Instead, let's concentrate on the amplitude of the signal. I see you've recorded some signals as low as 2.2 volts. That's a new one me. Just about every transmitter that I've tested from that era, they all employed PPM encoders - each and every one chucking out a signal amplitude equating to the DC input.

Your turn to elaborate.
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