Turnout control by servo - my experiences

[gregh]

I've noticed on a US forum, discussions on using servos to operate turnouts.
I thought I post my experiences of using them outside for 15 years.

I started directly connecting the servo arm to the turnout tie-bar, but soon realised that I couldn't operate the turnout locally, as the servo 'locked' it - so I had to run back to the operating panel.

So my next attempt had a 'handle' on the servo arm so I could move the turnout locally. But it was quite difficult to operate.

servo cover off capt.jpg (425.89 KiB) Viewed 5789 times

And both methods 'locked' the turnout, so it was impossible to 'run through' the turnout without derailing.

So for my 3rd attempt, I devised a slotted push bar. The slot allows the turnout to be operated locally, manually, in the normal way of 'pushing it over'.
All this is explained in this video...
https://www.youtube.com/watch?v=rj8gxwYHIM4

The turnout is not locked by the servo, so the normal over-centre spring holds it in each position, and it can be run through in the wrong direction.
As to how to operate/control the servos, I use Picaxe and pushbuttons.
But a simple solution is to use a ‘servo tester’ as shown at the end of my video.

Dave Bodnar has made a very good video using a 'servo tester', in this link.
http://trainelectronics.com/Servo-simpl ... /index.htm

While I haven't tried it, I think it would be very easy to use the servo tester with my slotted push bar, just by turning the knob in either direction until the spring pulls the turnout right across and then returning the knob to centre (neutral). Maybe with a mechanical stop on the knob, instead of the electronics used by Bodnar?

Some might wonder if servos are OK outside. I've only used 'normal' sized ones for turnouts, not the micro size. Mine are in small buildings, like this

IMG_7842.JPG (112.47 KiB) Viewed 5789 times

and even in a small 'signalling cupboard' as seen in the top pic, and the oldest has been outside since 2002.

I have also used servos to operate semaphore signals. These use the micro servos protected only by the ‘cupboard’.

comp sig1.jpg (421.54 KiB) Viewed 5789 times

comp sig2.jpg (308.56 KiB) Viewed 5789 times

[ge_rik]

Brilliantly simple, Greg. It's one of those solutions which makes me think, now why didn't I think of that? I use LGB point motors but that's only because they were in situ on the bad old days when I used track power. Thanks to your help, I now operate these using a Picaxe sysem - http://riksrailway.blogspot.com/2015/08 ... ts-by.html - If I was starting from scratch I would use servos - particularly as they seem to survive ok outside.

Rik

[tom_tom_go]

I am pro servo for operating points and signals even outside. Not had any problems with the weather although all my servos are mounted under the track as my line is raised. I use cheap micro servos and they have plenty of power to do what I want.

Here is what you can achieve (I don't use the uncoupling ramp anymore as I have got magnetic uncoupling working, KISS works for me!):

[ge_rik]

Nice video, Tom. I don't think I've seen that one showing the whole operation before.

Rik

[philipy]

Right guys, I'm gonna ask a stupid question!
I have points in 4 distinct locations, separated by many metres ( approx 40 from end to end). Am I right in thinking that I would have to either, 1) do what I think Rik did and put the Rx and electronics in one central box and then run wiring to each individual servo, or 2) have a separate Rx and electronics at each of the 4 positions?

[tom_tom_go]

One box Phil but that will depend on equipment you use and I think we have already discussed this at length in your own thread where you ended up using Tortoise motors?

[tom_tom_go]

Nice video, Tom. I don't think I've seen that one showing the whole operation before.

Rik

I posted last year I think?

All controlled from my Deltang Tx using Ardunio.

[ge_rik]

Right guys, I'm gonna ask a stupid question!
I have points in 4 distinct locations, separated by many metres ( approx 40 from end to end). Am I right in thinking that I would have to either, 1) do what I think Rik did and put the Rx and electronics in one central box and then run wiring to each individual servo, or 2) have a separate Rx and electronics at each of the 4 positions?

Hi Philip
Actually, I've got both systems - for the pointwork I have one central box and for the signalling, I have a box for each station (at least I would if I got around to making them for the other stations). I went for the central box for the pointwork because the wiring was already in place for track power. The Deltang points controller by default can handle up to seven servos (or point motors) - however, it can be modified to control up to 9 different receivers and 45 points/signals. You could therefore control four different receivers from one handset (ie one receiver at each location). You could power each receiver and its associated servos from separate battery battery packs or just run power cables to each location from a central power supply. It would be better, to my mind, than trying to run all the cabling needed for each separate servo from one central location.

Rik

[ge_rik]

I posted last year I think?
All controlled from my Deltang Tx using Ardunio.

Must have missed it. Suggests that it's worthwhile re-posting when a similar topic arises from time to time. Although I try to keep up to date with posts on the forum, it's easy to miss some - even with the 'New Posts' button.

Rik

[philipy]

One box Phil but that will depend on equipment you use and I think we have already discussed this at length in your own thread where you ended up using Tortoise motors?

Yes, I have been here before, I'm afraid, Tom. Trouble is that I haven't yet come to something that I'm comfortable implementing everywhere. The Tortoises worked fine when I first did them, but the spring wires are corroding and losing their Uumph and are not really viable outdoors long term.
I liked Rik's Picaxe solution when he first posted, but couldn't get my head around the programming and interfacing, at that time. I've been looking again in the light of Greg's posts and wondered if it worth me having a go, but wondered how much RC gear I would have buy, on top!

[philipy]

You could therefore control four different receivers from one handset (ie one receiver at each location). You could power each receiver and its associated servos from separate battery battery packs or just run power cables to each location from a central power supply. It would be better, to my mind, than trying to run all the cabling needed for each separate servo from one central location.

Rik

Thanks Rik. I really didn't like the idea of running all the cabling from one central box.

[tom_tom_go]

I think it's a waste of money that you will need 4 x Rx for each point because you don't want to wire to one location?

[gregh]

I am pro servo for operating points and signals even outside. Not had any problems with the weather although all my servos are mounted under the track as my line is raised. I use cheap micro servos and they have plenty of power to do what I want.

Very nice slow movement of the turnout.
What kind of control are you using to generate the servo signals? This thread seems to have assumed radio control is needed.

[tom_tom_go]

Hi Greg,

If you read my RWLR thread starting from here it should cover what you need to know:

https://gardenrails.org/viewtopic.php?f ... &start=165

[gregh]

Hi Greg,
If you read my RWLR thread starting from here it should cover what you need to know:
https://gardenrails.org/viewtopic.php?f ... &start=165

Thanks. I see you are an Arduino and Deltang man. ( I was hoping for another picaxe addict like me)
I read right through your RWLR pages - great reading and ideas. I wish I understood how your magnetic uncoupler works. Can you pull a wagon through it without it uncoupling?
I see you're been down the path of 'bouncing semaphores too. here's my attempts from a few years back.

[tom_tom_go]

This is a better video showing the how the magnetic uncoupling works:



When the chopper is under tension it will not try and lift.

I use the Arduino as it was given to me so waste not and all that. I have not researched the pros and cons between Ardunio vs Picaxe although there seems to be more freely available information and help with Ardunio for idiots like me who are not programmers or electrical pros.

[tom_tom_go]

Your signal bounce looks better than mine.

Could you dump the code here please so I can see how you do it (use the code tags to format it properly in a post).

Tom

[ge_rik]

Your signal bounce looks better than mine.
Could you dump the code here please so I can see how you do it (use the code tags to format it properly in a post).
Tom

Hi Tom
It's a quarter to one in the morning in Sydney and so, while Greg snoozes on, here's his Picaxe code for signal bounce which he passed on to me for my signals. I'll let him explain the process he went through in formulating the procedure - like most things Greg does, he took a very mathematical approach to it.
https://riksrailway.blogspot.co.uk/2016 ... phore.html

Rik
PS - As you can see from the introductory comments on the program, he's outlined the approach he adopted for the two procedures(raise and lower)

[gregh]

Your signal bounce looks better than mine.
Could you dump the code here please so I can see how you do it (use the code tags to format it properly in a post).
Tom

I thought yours looked better Tom! Thanks for the 2nd video on uncoupling too - all is clear now.
Thanks Rik for doing my work while I slept. That program looks complicated as it covers 4 signals.If you'd like the code for a simple 1 signal, as in the first video, I can try and dig that out. It's a few years ago now, so I've forgotten how it works too. I could try using that code tag method too.

[tom_tom_go]

Thanks Rik/Greg.

Can I have the code for one signal please as I am not familiar with Picaxe (I think that's another reason I prefer Ardunio as it uses C/C++ functions which I understand being an IT bod for my sins).