My current method of controlling the locos bound to different transmitters on my railway involves me carrying multiple 2.4GHz aircraft stick style transmitters out to the layout which can be cumbersome.
Each of my transmitters have been modified so that I can control Two (2) locos from the one transmitter (See "Mode 3 Transmitter" below).
After reading the descriptions in the forum and blog posts below, detailing how to change the transmitters to control (Four) 4 locos (or more depending on the number of channels a transmitter has e.g Six {6}), I decided that this may suit my situation and lighten the workload.
Forum Repackaging a commercial radio control transmitter
Following this method I converted a transmitter to test the concept of running Four (4) locos off the One (1) Transmitter.
To “repackage” the radio control into a box with knobs, I took the transmitter case apart and followed a modeller named “Tramcar Trev” method as below.
This was from Trev’s blog before it was discontinued plus what he posted on the forum so I hope it will be of the same use to people in the future as it was to me.
Making a commercial radio control suitable for railway use.....
Quote from blog;
I was trying to work out how to make the 80 degrees movement of the joystick into 300 degrees rotation battling all the while trying to maintain the electronic “integrity” of the whole thing. So I looked at the bits and there are marked B5K which is a linear 5000 Ohm variable resistor
The components for the conversion.
Problem; the potentiometers are 5K0 ohm linear ( that's what it says on the pots B5K0) but only the centre 60 degrees of the 300 degrees of "turn" are used and I want to replace the pots and be able to use the full sweep of 300 degrees.
Solution; as the pots are 5K over 300 degrees rotation then divide the 5000 by 300 = 16.6 Ohms/degree of rotation. Ok so then as I have the centre 60 degrees actually used there are 996 ohms in the swept area using the existing joystick. So if I use a 1K0 pot with a 2k0 fixed resistor on each "end" I end up close enough to 5K0 overall and the pot can be used for its full travel.
So just to be sure I measured one of the pots with a meter and the results were close enough to my theoretical calculations.
Result; Not sure when Murphy arrived on the scene but so just to be sure that this was going to work I soldered up the 2 fixed resistors and connected it all together only on 1 channel and gave it a try….. Nothing but a flicker of movement.
Initial replacement
For some reason I checked the pot again, the one I had removed and noticed in letters fully 10 microns high “80o”.
Ahhh; then it all fell into place (Murphy had struck) these potentiometers used are specifically made for this purpose (as I had read on the net) so it was a simple matter to delete all reference to my calculations and simply replace the pots with 5K 300o ones – AND IT WORKED!!!!
The final replacement
Now it’s a simple job to mark out the new box, install the switches, buttons and battery charger socket. Then the battery holder and main PCB can be installed. Some components will have to be moved off the PCB and the wiring extended so that they can be mounted on the new case. I can see no reason why this won’t work unless Murphy strikes again…..
The chrome plated snap ring is the key to disassembly
The bind button, even though it looks to me on the PCB to be a simple momentary contact button, actually did need a STDP button which once installed got it all sorted out.
The only other tricky bit was the actual soldering of the coax for the antenna.
I successfully tested binding Three (3) Receivers to the Transmitter. I didn't think the extra receiver was required for the test as Three (3) would suffice to prove the concept.
Then I connected Three (3) motor controllers (ESC's) to each Receiver and motors and controlled each motor separately from a corresponding channel potentiometer on the Transmitter.
At the end of testing the converted transmitter board then became the basis for the repackaging.
My method involved following most of the blog method but with some refinements to suit the packaging I was doing.
Changes I made were:
- Removed the "Trainer" plug as it was not used.
- Removed the potentiometer mounting boards and wired directly to the pots to make fitting easier.
- Install a 9.6V NiMH rechargeable battery pack that provides over Two(2) hours of charge.
- Relocated LED indicator from on board mounting to the front panel by way of extension wires.
- Removed board mounted power switch and replaced it with a On/Off/Charge switch mounted on the front panel.
- Cut the antenna out of the housing (being careful not to cut the thin coaxial cable connecting antenna to RF board) trimmed it and located it inside the box, testing did not reveal any effect on the range of the transmitter (original spec was an 800ft range).
- I did not move the "Bind" switch as this transmitter is dedicated to the Four (4) locos.
 |
| Stick Transmitter internals |
 |
| Repackaged Transmitter internals |
 |
| Antenna Location |
After completing the repackage I bound each Receiver in Four (4) locos that use my centre off motor controllers (Pololu, Syren 10 and Viper) to the Transmitter, I now only need to take one box out to the layout to run four (4) locos instead of two (2) stick transmitters as in the picture below.
NOTE;
I had to orientate the pots so that the centre on the knob was aligned vertically.
I did find that I had to reverse channel 4 "RUD" via its switch, not sure if it had anything to do with the Syren 10 motor controller.
 |
No comments:
Post a Comment