Large Scale Central

Downsizing / Repackaging a 2-Stick 2.4 GHx Transmitter

Electronics Power and Sound
#1

With the advent of low cost 2.4 GHz Spread Spectrum R/C systems, there has been a trend toward using them in their native mode (with servos) to control live steam, and with with an electronic throttle to control battery operated locos. The system works well but there is one big negative - the size of the transmitter. Low Cost equates to Park Flier Aircraft which equates to large 2-stick transmitters…

If one looks inside the large plastic box that houses the above radio, you find that the electronics are quite small and there is an integrated 4 AA battery box. The largest components are the sticks which aren’t really needed for train control. I drew this simplified lock diagram…

The above was done from memory, so I might have missed a few switches. It seems to me that it would be a fairly simple job for anyone with basic electronics skills to replace the stick components with something smaller and fit the whole works into something about the size of a small hand-held radio. The way I see it, the job requires just a few decisions, some of which I don’t have the data to make… 1. Which controls require more than on-off ? I think there would be only one - Throttle. but I’m not familiar with programming needs of ESC’s. 2. Which controls need 3-State switches ? I’m thinking Direction (Forward, Neutral and Reverse) but there may be others. 3. Should any controls be 2-State (On/Off) ? 4. Does trim need to be external, or would an internal trim-pot be acceptable? If external, would a small shaft be good enough or is a knob or slider needed? Given the answers to the requirements, it seems to me I would only need to measure the values output by the sticks in various positions, and replace them with either potentiometers, or a switched resistor network. I’d like to hear your opinions and feedback on technical requirements. This isn’t a project I’m likely to take on immediately, but it might be a good rainy day / hiding in the air conditioning / winter project.

#2

Jon,
I’m surprised no manufacturer has done this, yet. I really like the small size of my current RCS transmitter.

I know that you’re looking at controlling live steam, but I’d sure like to have this done for electric locomotives.

It would be just a tad different from what you have proposed.

You’d need the following:

  1. Direction: two state: forward/reverse
  2. Bell: two state: on/off
  3. Whistle: two state toggle - so you can “play” it.
  4. Lights: two state: on/off
  5. Throttle: I’d prefer some sort of sliding control, but it may be hard to have fine control, especially at low speeds.
  6. Perhaps some other two state switches to play the other sounds typically available on a Phoenix sound card.
#3

I’m thinking both Live Steam via Servos and Battery via an ESC like Tony’s Beltrol or Del’s RailBoss.

The Three State reverser is a live steam thing, but not required.

#4

It’s time to start now!

#5

Some people are useing the small E-Flite transmitter like comes with a E-Flite Blade MCX heli with a Railboss . These are smaller and lighter and handy .

(http://www.horizonhobby.com/ProdInfo/EFL/450/EFLH1064-450.jpg?rand=107769209)

http://www.horizonhobby.com/Products/Default.aspx?ProdID=EFLH1064 The $42 dollar price is hard to beat . The ant is 3 inches , small xmtr

#6

Still TOO BIG

#7

The form factor and buttons are the main reason I still use the old standby RCS. I REALLY dont like pushing levers to toggle the bell, or change directions. And I’m with Bruce, the throttle could be either buttons, a slider, or maybe a knob like Airwire does.

#8

John,
The idea is doable, especially as Digital Proportional gives unparalleled speed control.

The problem is cost.

It is simply not economically feasible to rework an existing system to do what you suggest and offer them for sale.

What is needed, is to start from the ground up.
It is entirely possible to start from scratch and get one of the Chinese stick radio manufacturers to miniaturise the operation and design it in such a way that it would be usable by both live steam and battery ESC’s, even when in a small sized hand piece.
All it will take is money, and do you have any idea how much that would cost?

One day I will do that, but as I don’t have the wherewithal to finance the development, it will have to wait until I do.

In the meantime, why not get your feet wet and try one of the existing low cost systems. The newer TX’s have short stubby antennas and some of them only use 4 x AA size batteries. So the TX is lighter.

#9

I’m sure it would make a lot of sense to start from scratch - IF one were trying to resell it.

I’m intrigued by the idea of reworking an existing system, but my electronics courses are all from the last century and I am not sure how much I retained. It’s almost worth it to me to buy one and get out the razor saw. :wink:

#10

With the 4 AA batts , it weighs 10 oz . I already have them and used them with helcopters , I like them because they stay put , where ever you sit them down , the left stick is throttle and it is smooth control and stays where you set the speed too , and there is no push the button over and over , just move the stick . Works well for me here , of course I like to keep things real simple , for fun .

(http://www.horizonhobby.com/ProdInfo/EFL/450/EFLH1064-450.jpg)

#11

Thanks Tony -

I’m thinking of doing it as a one-off using commonly available parts. I wouldn’t be doing it to sell. If the procedure can be made simple enough, it might be something a few guys might want to do, perhaps as a group project.

I already have a Spektrum DX5e, so that would be my starting point. I don’t expect the potentiometer values to be the same for other brands, but the method should be similar.

What I’d like to hear from you, is IF you could afford to develop it - what would be you design criteria for controls?

It would be great to do push-button like the classic RCS, TE and Revo - but that would add another layer of electronics and software that I don’t have an interest in developing. I think a nice Throttle knob like AirWire would be my starting point. Cheap sliders are too unreliable.

So here’s what I have so far based on compatibility with Sevos for Live Steam or Beltrol Eclipse ESC for Battery Power…

Throttle - Replace stick with large knob on a potentiometer
Throttle Trim - Mini center-off momentary contact toggle switch (digital trim)

Direction [Elevator] - Replace stick with 3 Position momentary toggle switch (center off)
Direction Trim - Mini center-off momentary contact toggle switch (digital trim) {Used for Live Steam/Servo application}

Sounds 1 & 2 [Aileron] - Replace stick with 3 Position momentary toggle switch (center off)
Trim - Mini center-off momentary contact slide switch (digital trim) - Internal only

Sounds 3 & 4 [Rudder] - Replace stick with 3 Position momentary toggle switch (center off)
Trim - Mini center-off momentary contact slide switch (digital trim) - Internal only

CH 5 Programming - 2 Position toggle switch

NOTE: Beltrol has automatic directional lighting - Always ON if Rx is on.

For Sounds, I’d need to figure out if a pair of momentary push-button switches could be used rather than the toggle. That would work better for the horn.

#12

Hi Jon.
Off the top of my head that is basically what I would do.
However, if the Digital Proportional controls (other than the throttle control) are replaced by any sort of non DP control the live steam loco operator would lose the ability to control the Johnson bar cut off, for example.
Whilst that is not normally used for small scale live steamers there are some locos that use it to control the speed as well as the direction. I guess it would be possible to reassign the servo output of the throttle stick which is non sprung.

I am tied up for a few hours today but will get back to you asap.

#13
TonyWalsham said:
[i][/i]if the Digital Proportional controls (other than the throttle control) are replaced by any sort of non DP control the live steam loco operator would lose the ability to control the Johnson bar cut off, for example.[i][/i]
Good point. I didn't think of that because I'm presently using the throttle stick for the Johnson Bar servo and dialing the throttle by hand. The Johnson bar controls the speed. However, If I were to add a second servo in the future, I would want D/P control. So I guess I'll be looking at two knobs.

No rush to answer - It’s late here and I’m signing off.

#14

A smaller Tx would be great. I know it would be popular, but as Tony stated, from a commercial point of view … it ain’t cheap. The electronics are simple. It is primarily a mechanical packaging exercise. Home grown would be a nice project. Commercial? Not me.

Since I have been using the commercial hobby radios, I really don’t mind the size at all. At first I thought I had to have the Tx in my hand or around my neck or something all of the time … but why? I run trains continuously and the only time I need the Tx is to get the thing going or to put it away. Of course, most folks want it handy and in there pocket or whatever, in case of an emergency. I have learned several things over the years. First of all, if you have good track work, there are seldom any emergencies. Secondly, when there is an emergency it doesn’t matter how big the Tx is or where it is at, it is already too late!

The larger size is still easily placed in a nearby location (if you don’t want to hold it). The smaller size E-Flite TX that Dennis referred to is even lighter and smaller. This size is similar to a video game controller; much lighter and easier to handle than a standard Tx. The E-Flite is a 4-channel Tx and will work fine with the RailBoss (Beltrol requires 5-channels).

If anyone pursues this project please keep us in the loop.

#15

Sorry guys , I use my small E-Flite transmitters with a couple of Dels Railboss units , I was just guessing that the Beltrol also worked with the 4 channel xmtrs .

#16
Quote:
... I run trains continuously and the only time I need the Tx is to get the thing going or to put it away.
Therein lies the issue for me. Most of the time, I'm doing switching, so it's very nice to have one-handed control. That frees the second hand up for throwing switches and lifting cut levers. (TOC, I'm no longer lifting Kadees up and over each other. Aren't you proud? ;) ) Constantly having to sit the transmitter down to uncouple and throw switches got quite tiresome. (Okay, I used the antenna to throw the switches sometimes.)

I’m planning on switching my live steamers over to 2.4 gHz this summer, so I’ll probably play around with reconfiguring something then. Even if you’re just repositioning the four stick pots to horizontal, you can decrease the form factor quite a bit.

Later,

K

#17

I’m with Kevin on this one. I REALLY like to be able to operate with one hand as I do a lot of switching. If I just want to run a train around the loop, I get out my live steam Shay - which only has manual control.

I guess part of me objects to controlling a train using a joystick. It seems OK for planes and helicopters, but just seems wrong for a train. I wouldn’t mind so much if the joystick only moved in one dimension. And there was only one of them. :wink:

Sounds like a very neat project.

#18
Dennis Paulson said:
Sorry guys , I use my small E-Flite transmitters with a couple of Dels Railboss units , I was just guessing that the Beltrol also worked with the 4 channel xmtrs .
No problem Dennis. This a generic thread :D I believe in my original thread I mentioned RailBoss as wel as Beltrol and good old servo control.

Del - Thanks for chiming in - If I’m going to do this I want my configuration to be compatible with all three systems I mentioned above. I’ll need to study your RailBoss instructions, as I did Tony’s Beltrol Eclipse yesterday, so I can be sure the control type is compatible.

I hear what you are saying regarding continuous running, but I am not from that world. My layout, for now, is strictly point-to-point. I have grades that need to be accommodated with the throttle, one reverse loop, and a Wye that require stops, starts and direction changes. I also like to do a bit of switching - so convenience in a small single hand package is my goal.

Kevin - I’m not sure I follow your statement “Even if you’re just repositioning the four stick pots to horizontal, you can decrease the form factor quite a bit.” What do you mean by horizontal (compared to how they are in the 2-stick) ? Could you do a rough sketch ?

#19
Bruce Chandler said:
[i][/i]I wouldn't mind so much if the joystick only moved in one dimension. And there was only one of them. ;)

Sounds like a very neat project.


Now there’s an idea :smiley: It cuts the cost by utilizing one existing stick. Could you accept using the side-to-side movement on that stick for two of your four sound triggers (if an Eclipse ESC was used)? You could still do the horn and bell on push-buttons or toggles.

Speaking of Bells. The Beltrol Eclipse has a latching sound trigger option. So a single push starts the sound and it continues until another push stops it. Given this option, would you rather use a push-button (one push ON, second push OFF), or a toggle for the bell function? The advantage of the toggle is that it would be backward compatible with the Beltrol Classic. I’m not sure yet what RailBoss requires.

#20

Id rather not move a joystick to toggle sound, especially a 4-way stick. I’m likely to hit accelerate when Im trying to blow the whistle or something.

How about a knob for throttle, switch or joystick for direction, and buttons for everything else?