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Radio Control Components & Size Information
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 Posted: Thu Nov 17th, 2011 07:29 pm
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Toeffelholm
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Ok Dan,

then, to my opinion, there are two possibilities left.

You can check if there is a difference by using a normal, non coreless motor.
A coreless motor starts in a very small voltage and current range, that maybe outside the control possibilities of your esc.

Second I found on the net, that there are basical problems reported using this esc especially together with spektrum but also with other systems, although not in the way you described.

But both would mean, that you may better choose another esc.

Juergen

Last edited on Thu Nov 17th, 2011 07:32 pm by Toeffelholm



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 Posted: Thu Nov 17th, 2011 10:11 pm
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dan3192
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Woodie, thanks for the encouragement.  It's mostly my inexperience with RC in general that keeps me going at a snail's pace.  I'm also the type that has to know all the details before I make a move.  Thanks to Free Rails, I can sit at my computer and soak up ideas and experience and make some decisions.  

My prototype will be modified.  A smaller battery pack and possibly rearranging some parts will allow me to finally mount the shell on the chassis.  I'll post another photo as soon as I have something decent to look at.  Thanks for your follow-up.

Dan

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 Posted: Thu Nov 17th, 2011 11:56 pm
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Herb Kephart
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Toeffelholm wrote



But both would mean, that you may better choose another esc.

Juergen

Before doing that, try putting a 50-60 ohm resistor across the motor brushes to "load" the ESC a little more and see if it makes the control better. The coreless motors draw very little current, as Juergen said, this will increase the amount of motor current slightly --about 2 tenths  of an amp at twelve volts-- and might be just enough th "trick" the ESC.

One other thing-- is there a capacitor across the brushes of the motor now? (usually a little brown pill like thing)  If so it may cause the described symptoms. Speed is controlled by a series of off-on spikes of voltage. Short spikes==low speed. A capacitor will in effect "fill in" between the spikes and cause an increased speed of the motor.

Herb 





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 Posted: Fri Nov 18th, 2011 02:02 am
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dan3192
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Juergen,

Thanks for your comments.  You've have me thinking about something I should have thought of before.  I can certainly use different motors and observe the results.  This I will do, but your remark about coreless motors made me realize a few things. 

First, I am operating my engine on test rollers, or on a test track, which means almost no load for the motor.  Isn't no load speed always higher than when under load? 

Second, given the high efficiency of the motor, and the rotor being supported by ball bearings (low turning friction), it sounds reasonable the motor would run at high speeds even with a low starting voltage.  Importantly, there is a difference in motor torque between the lower and higher speeds, but I do feel the speed range could still be improved.

You may be right about using a different ESC based on what you found, plus my own experience.  I'll be asking a few more experts about this before making a switch.  There's still a good chance I'm not setting it up properly, so maybe they can be more successful than me.  It will not be a big deal swapping out the old ESC for a new one, especially a smaller one.  

Regarding the new Losi conversion kit, I spoke with the R/C manager at a local hobby shop and he advised me not to use an air transmitter with a ground ESC because they are set up differently.  I also called the Spektrum technical support hotline and they likewise recommended not to pair these up.  They stated that ground and air receivers have different signal protocols and DSM2 and DSMX transmitters are designed to be used with aircraft.

Spektrum also mentioned they are coming out with a new DX7 Tx around December.  The DX7 and current DX8 can be used with their new telemetry system.  I read there is a free app for smart phones, ipads and the like, which allows receiving aircraft telemetry signals.  This means you can use your DX5 or DX6 and still monitor performance "on the fly". 

This has relevant implications in that motor speed can be converted to scale mph, and just like for aircraft, monitoring battery (low) voltage lets you know when its time to bring your engine in for a charge.  Telemetry also lets you know if motor or battery are getting too warm, as might be the case with a long consist or uphill climb.     

In any case, a slight rebuild of my AMD-103 lies ahead, and we'll hopefully soon have the shell installed as well.

Dan  

 

 

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 Posted: Fri Nov 18th, 2011 02:26 am
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dan3192
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Juergen,

I should have said "...he advised me not to use an air transmitter with a ground receiver."  Sorry, getting late, must be getting tired.

Dan

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 Posted: Thu Dec 1st, 2011 05:31 pm
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dan3192
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Hello,

Back again, but still having problems.  In a nutshell, my AMD-103 still runs great, but in a narrow speed range.  I took some motor readings before yanking out the 6 volt alkalines, based on a conversation with an RC shop owner in upstate NY. 

With a 6.21 supply voltage, results were as follows for min. throttle & max. throttle:

4.72 volts & 5.73 volts

He had suggested I try a higher voltage since my Spektrum Rx is rated at 9.6 volts.  Substituting a 9 volt alkaline with a 9.28 supply voltage gave the following results:

7.32 volts & 8.6 volts.

It appears the speed range only shifts upward for an increased supply voltage.  Herb, there are no capacitors on the motor I'm using and adding a resistor across the motor leads had no noticeable effect. 

Also made mention was that my DX5e has a limited "resolution" when compared with upper end Tx's like the DX8, which can also program desired throttle ranges and configurations.  Given the cost and complexity, this will not happen at this time.  I will continue the search for answers for this project, while completing construction of my second prototype, which takes a slightly different approach.

Thank you all again for your advice and support.  We'll get back soon.

Dan        

 

 

 

 

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 Posted: Thu Dec 1st, 2011 06:15 pm
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W C Greene
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Dan-I know that you are probably getting a bit discouraged by now. All I might put forth is to spend even more money (about $80 US) for a complete LOSI MICRO T car-transmitter, car, battery...and install that board in your loco. This sounds like throwing good money after bad, but I can ASSURE you that the Losi board, transmitter, and appropriate battery WILL OPERATE your locomotive in a satisfying manner. It seems that you are going down the "garden path" buying this neat thing and that high tech device and not getting anything accomplished. What works for some doesn't work for others, but what I propose does work as advertised. This is only my opinion, but I have been running r/c locos for around 10 years now with this "old fashioned" stuff and wouldn't change a thing. Good luck...
Woodie



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 Posted: Fri Dec 2nd, 2011 02:49 am
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dan3192
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Woodie, thanks for the encouragement.  I can use some at this point.  I trusted the guy that sold me the equipment, but his support is just not there.  I know I asked him if I can get the full speed range with my motor.

It's good to know the Losi stuff works.  I may just go that way very soon.  I started out with some definite goals in mind, i.e., full speed range and reversibility, on-board control of track switching, basic engine sounds, the ability to haul six or eight passenger cars.  Visions of LED-driven fiber optic lighting, an on-board camera and contactless charging were also dancing around in my head as I anticipated overcoming each challenge and forging ahead with the next nifty feature.

The speed range problem is a disappointment, but also a reality check.  I've gotten too close to the forest to see the trees.  But, down deep, I knew all the technology I needed was already here.   What I was trying to do is re-format and re-arrange all this neat hardware and software into one unique engine and finally satisfy my desire for a layout free of any and all track design limitations.  Easier said than done.

Although, If I was CEO of Horizon (Athearn, Roundhouse, Spektrum, Losi, E-Flite, etc.), I'd push for a universal RCC board with an open architecture using a lot of the ideas now being developed and get this whole radio control thing going.  But I'm not, and I will have to "go with the flow". 

We've had a death in the family and I'll be in Texas in a few weeks to see my new granddaughter.  So I'll be taking time off and taking a step back before moving ahead again.  My wishes to all for a Happy Holiday Season.

Dan

 

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 Posted: Fri Dec 2nd, 2011 02:20 pm
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W C Greene
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Dan-if you will be anywhere close to Dallas, let me invite you to drop by and visit. Take care and have a Merry Christmas.
Woodie



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 Posted: Fri Dec 2nd, 2011 02:35 pm
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dan3192
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That's nice of you to suggest that.  We fly into Dallas-Ft.Worth 12/28 and return home on 1/3.  We'll be staying in N. Richland Hills.  How can we e-mail each other?

Dan

 

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