Repackaging a commercial Radio Control transmitter

[nicebutdim]

I completely agree with Trev there, the simpler radios are easier to dismantle and understand in operation.
The esc I use is normally a forwards/backwards one (viper loco10) but it is programmable with where the neutral position can be placed, so I set it with the stick fully down (pot on my controller fully anticlockwise), which I find gives better control. As the viper escs don't provide for directional lighting this method helps as the direction relay is in parallel with another relay that controls the lights. Probably not the simplest of methods, but it works and the loco is a real joy to play with operate, especially for shunting with.

 

[gregh]

Great innovation. Some good ideas to 'borrow' in your work.

 

[tramcar trev]

I completely agree with Trev there, the simpler radios are easier to dismantle and understand in operation.
The esc I use is normally a forwards/backwards one (viper loco10) but it is programmable with where the neutral position can be placed, so I set it with the stick fully down (pot on my controller fully anticlockwise), which I find gives better control. As the viper escs don't provide for directional lighting this method helps as the direction relay is in parallel with another relay that controls the lights. Probably not the simplest of methods, but it works and the loco is a real joy to play with operate, especially for shunting with.

Another good idea.. I had not thought of making the lights directional simply by utilising the output polarity of the ESC. Thanks for that.

 

[Dtsteam]

Well I never realised you could run a servo in parallel with an esc so we've all got a lot out of this thread.

 

[No72]

Well my control box seems to have died... Its the actual little bit in the shielded box that does the transmitting that's having problems.... Anyway for AU$27 I have another on the way which will work with the existing Rx's and I'm assured there are plenty of the Rx to match this transmitter available for AU$15.... Seems the V2 model is still quite popular with the flying crowd and for the price I guess its good value. So it will all start again... The box will be slightly different this time. As I dont have balloon loop termini each knob will be centre off and forward / reverse depending on which way the knob is turned. Ch6 will be used to turn on and off headlights and smoke on the Baldwin.. Sound is automatic as each car starts up. Its by far the most cost effective way of doing it with most other dedicated RC solutions costing in the hundreds.... Do Y'all want another bit by bit demonstration?

 

[PhilP]

Well my control box seems to have died... Its the actual little bit in the shielded box that does the transmitting that's having problems.... Anyway for AU$27 I have another on the way which will work with the existing Rx's and I'm assured there are plenty of the Rx to match this transmitter available for AU$15.... Seems the V2 model is still quite popular with the flying crowd and for the price I guess its good value. So it will all start again... The box will be slightly different this time. As I dont have balloon loop termini each knob will be centre off and forward / reverse depending on which way the knob is turned. Ch6 will be used to turn on and off headlights and smoke on the Baldwin.. Sound is automatic as each car starts up. Its by far the most cost effective way of doing it with most other dedicated RC solutions costing in the hundreds.... Do Y'all want another bit by bit demonstration?

Yes please..
Always good to see how others approach these projects, and helps dispel the myths that everything electronic is *really* difficult.
PhilP.

 

[No72]

Well first things first. The antenna for what I am using need not be outside the plastic box. If I was flying a plane 20 metres away form me then yes you need the external antenna. for what I'm using maybe 5 metres max the antenna can be just laid down inside the box... If that is too bulky then all I have to do is cut a bit of tinned wire to 1/4 wavelength of the 2.4 ghz which for all practical purposes is 31mm and solder it to the antenna pad.... The length is apparently critical, too long and you can burn out the transmitter too short and it wont work efficiently. This means I could actually mount the box to the shelf and power it from the traction supply thus eliminating the transmitter battery. That would men I could have a bigger box with digital readouts for each channel, the more useless information displayed the less critical the casual observers eyes....

 

[GAP]

Well first things first. The antenna for what I am using need not be outside the plastic box. If I was flying a plane 20 metres away form me then yes you need the external antenna. for what I'm using maybe 5 metres max the antenna can be just laid down inside the box... If that is too bulky then all I have to do is cut a bit of tinned wire to 1/4 wavelength of the 2.4 ghz which for all practical purposes is 31mm and solder it to the antenna pad.... The length is apparently critical, too long and you can burn out the transmitter too short and it wont work efficiently. This means I could actually mount the box to the shelf and power it from the traction supply thus eliminating the transmitter battery. That would men I could have a bigger box with digital readouts for each channel, the more useless information displayed the less critical the casual observers eyes....

Yes Trev the length is definitely critical to get max power transfer an reduce VSWR to a minimum.
VSWR or Voltage Standing Wave Ratio will affect a transmitters performance if the antenna is not at the correct length (usually 1/4 wavelength) the reflected output does some weird stuff.
If you want to fry your brain have a look at this, http://www.antenna-theory.com/definitions/vswr.php or just make the antenna the right length.
To be accurate the bare wire 1/4 wave 2.4GHz antenna length is 31.25 mm

And yes please another bit by bit demo will be most welcome (well for me anyway).

 

[GAP]

Another good idea.. I had not thought of making the lights directional simply by utilising the output polarity of the ESC. Thanks for that.

Trev,
I have wired my LEDs across my ESC output and get directional lighting that way.
They do not come on till the voltage reaches a level but I just explain away that as the driver just turns on the lights as he starts up (works for me as I run Rule 8 My Railway My Rules)

 

[No72]

Yes Trev the length is definitely critical to get max power transfer an reduce VSWR to a minimum.
VSWR or Voltage Standing Wave Ratio will affect a transmitters performance if the antenna is not at the correct length (usually 1/4 wavelength) the reflected output does some weird stuff.
If you want to fry your brain have a look at this, http://www.antenna-theory.com/definitions/vswr.php or just make the antenna the right length.
To be accurate the bare wire 1/4 wave 2.4GHz antenna length is 31.25 mm

And yes please another bit by bit demo will be most welcome (well for me anyway).

Ok... Yeah got the critical bit... But looking at most of these antennae they are in reality just a bare section of the coax cut to the precise length. this means they are shielded for most of their length. So how does a whip sound simply soldered to the antenna pad on the board 31.25mm long with no shielded cable at all? I believe its a simple mono pole and someone else has done something similar. If it was a di pole then there would be an exact counterpoise to the antenna, yes?

 

[No72]

Trev,
I have wired my LEDs across my ESC output and get directional lighting that way.
They do not come on till the voltage reaches a level but I just explain away that as the driver just turns on the lights as he starts up (works for me as I run Rule 8 My Railway My Rules)

I have been employing "rule 8" extensively. I believe "rule 8" to be an Aussie idea. Here it goes back to a chap named Basil Miller who was the tramway superintendent at Bendigo when it was a working service. He was also a keen gricer and was often found trackside photographing his trams and because he could he used to schedule cars onto differing routes to photograph them. One day he was asked why he wanted a particular tram dragged out of the depot requiring several others to be moved and he told the Starter "Rule 8, its my expletive deleted tramway and I'll run it as I see fit, thank you very much"....

 

[GAP]

Ok... Yeah got the critical bit... But looking at most of these antennae they are in reality just a bare section of the coax cut to the precise length. this means they are shielded for most of their length. So how does a whip sound simply soldered to the antenna pad on the board 31.25mm long with no shielded cable at all? I believe its a simple mono pole and someone else has done something similar. If it was a di pole then there would be an exact counterpoise to the antenna, yes?

The antenna element is the wire and the 'groundplane' would most likely be the metal shield in your picture.

The bare section of the coax would be the antenna while the shielded bit would be the feed and also provides the groundplane.

A dipole would have a groundplane element and is usually 1/2 wavelength ie antenna 1/4 wave and ground 1/4 wave and the signal is generally fed into the centre but that is not a hard and fast rule.

 

[No72]

Still waiting for a few components before I repackage the commercial 6 channel set into a single box... I shall replace all the Potentiometers with wire wound ones. I've had a look that the ones that are part of the new Tx and boy oh boy are they C&N... Just a carbon track on a thin sheet of phenolic resin board, not even a ceramic substrate. Its no wonder they are Romeo Sierra on the old Tx... But I guess for AUD$27 what would I expect.....

 

[No72]

Just thinking that I could go for a notchy experience by replacing the potentiometer with a multi position rotary switch. Most trams have 7 positions, 5 series and 3 parallel but Id have to go t with a 12 position switch or a 6 position switch with reverser switch for each channel or tram.
So getting down to the nitty gritty the Pots are 5000ohms end to end, half way and therefore "stop" is 2500ohms from either end. So with a 12 position switch the centre pole would be stop and then each of the poles would have around a 420Ohm resistor across them so that when you click onto the last one its high speed.... The resistor values could be tweaked by practical experiment I guess.Then make up a neat little imitation tram controller that would have a discrete 6 position rotary switch to select each channel or tram..... Obviously I'm inspired by the late great Eric Thorntons controller.... On the other hand am I going overboard on all this? Would every tram need the same motor/s?

 

[Dtsteam]

Well if you have 300 GBP to spare then this may look the part
http://www.rideonrailways.co.uk/accessories/page15.html

A bit more utilitarian than Eric's controller. One day I'll find out who has the patterns and get one cast off. The bit that made the difference was a decent star wheel. I've used rotary switches but they are a bit pansy. I found a ceramic RF rotary switch ages ago and that had a lot of bite, but I've never seen one since. It ended up in a sort of camshaft controller which lives in a dark corner of the attic.

I've also seen someone use a 12 meccano chain sprocket on top of the rotary switch. That appeals as you could blank out notch six and get a nice swing into parallel.

 

[GAP]

Just thinking that I could go for a notchy experience by replacing the potentiometer with a multi position rotary switch. Most trams have 7 positions, 5 series and 3 parallel but Id have to go t with a 12 position switch or a 6 position switch with reverser switch for each channel or tram.
So getting down to the nitty gritty the Pots are 5000ohms end to end, half way and therefore "stop" is 2500ohms from either end. So with a 12 position switch the centre pole would be stop and then each of the poles would have around a 420Ohm resistor across them so that when you click onto the last one its high speed.... The resistor values could be tweaked by practical experiment I guess.Then make up a neat little imitation tram controller that would have a discrete 6 position rotary switch to select each channel or tram..... Obviously I'm inspired by the late great Eric Thorntons controller.... On the other hand am I going overboard on all this? Would every tram need the same motor/s?

The notch idea sounds good, how are you planning to activate the reverser switch to achieve reverse below the halfway point?

One transmitter (Tx) with multiple receivers (Rx) bound to it could limit the number of trams you could run at one time, if you had more than one they would all be going in the same direction at a similar speed (speed being influenced by motor differences).
When motor differences come into play and cause problems you might have to experiment with speed matching, possibly using current limiting devices on the motor inputs.

I have modified some of my transmitters so that the left and right sticks operate in the same way so I have control over speed and direction of 2 locos on the one, that may be a way to go for operating two at a time.
See mode 3 transmitter on this page from gregh.
http://www.members.optusnet.com.au/satr/2point4GHz.htm

 

[PhilP]

The notch idea sounds good, how are you planning to activate the reverser switch to achieve reverse below the halfway point?

One transmitter (Tx) with multiple receivers (Rx) bound to it could limit the number of trams you could run at one time, if you had more than one they would all be going in the same direction at a similar speed (speed being influenced by motor differences).

With centre-off control, you can use a single channel 'per tram', so 6-7 should be possible?

 

[GAP]

With centre-off control, you can use a single channel 'per tram', so 6-7 should be possible?

Of course one channel per tram/loco, that is what I am doing myself with my modified Tx left stick = #1 right stick = #2, that will teach me to think things through before I write.

I am still at a bit of a loss about the centre off, I'm guessing that is a function of the ESC being used?
I have some that are bidirectional but others are just unidirectional and require a reversing switch to be operated hence the question.
Interested in which ESC is being used.

 

[No72]

With centre-off control, you can use a single channel 'per tram', so 6-7 should be possible?

Confusing... My ESC's are (wait for this) Bustophedron. That means they work each way so you end up with using a conventional radio control Tx with each joystick when at centre being "off". Move it one way or the other the tram moves forward of reverse. So with my 6 channel set I use 5 channels for tram control, i.e. each channel provides speed and direction control and Ch6 is used to turn lights on and off and smoke on the steam tram etc.
I use single and double switches off a single channel. The double requires different operating techniques but seems to work well enough , 1 click = 1 option, 2 clicks = the other option. 3 clicks = both 1 & 2 options are on 4 clicks turns all off..... A picture speaks a 100 words so here are the listings.
Single channel switch; https://www.ebay.com.au/itm/1pc-RC-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Double channel switch; https://www.ebay.com.au/itm/Two-Cha...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

ESC's https://www.ebay.com.au/itm/10A-Bus...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

https://www.ebay.com.au/itm/RC-10A-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

This ESC is problematic probably because I'm not drawing enough current; https://www.ebay.com.au/itm/ESC-Bru...d66e27c92:g:TDoAAOSwak5Zyw2g&autorefresh=true

 

[No72]

Of course one channel per tram/loco, that is what I am doing myself with my modified Tx left stick = #1 right stick = #2, that will teach me to think things through before I write.

I am still at a bit of a loss about the centre off, I'm guessing that is a function of the ESC being used?
I have some that are bidirectional but others are just unidirectional and require a reversing switch to be operated hence the question.
Interested in which ESC is being used.

I used to use single direction ESC's when I had the outdoor tramway because I had balloon loop termini. This layout is too cramped to be reaching around to throw switches... Posted the details of the ESC's one post up. Lets keep on this.