Servo's for Signals

Stuart Barker
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Servo's for Signals

Postby Stuart Barker » Wed Feb 18, 2015 4:16 pm

Dear all

I read with great interest Mr Robertson article page 31 of Scalefour News No.191 Feb 2015, LMS Ground Signals for Slattocks Junction.
My particular interest is the servo's he managed to purchase from e-bay. I am currently in the planning process for my layout and like the idea of using servo's for operating the semaphore signals, trying to obtain a more cost effective solution than using the tortoise motors which I am using for some of my points.

Does someone know what the make & model of these servos in the article are?

I have done a little research so I am looking to go down the route of a very simple solution at this stage.

Many thanks

Stuart

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David B
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Re: Servo's for Signals

Postby David B » Wed Feb 18, 2015 7:51 pm

Martin Lloyd wrote an article in MRJ 201 (2010) about semaphore signals and servos.

The commonly used servos are Tower Pro, the 9g.

RedDragon
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Re: Servo's for Signals

Postby RedDragon » Wed Feb 18, 2015 8:50 pm

Search for Tower Pro SG90 on Ebay, they can be bought for silly money, cheapest at about £2.19 each.

You will then require a driver/setter board - Merg, Wizard Models and at least 3 other companies do them.

SteveT

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grovenor-2685
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Re: Servo's for Signals

Postby grovenor-2685 » Wed Feb 18, 2015 8:58 pm

David B wrote:The commonly used servos are Tower Pro, the 9g.

Designated as the SG90, search Ebay for them.
Note you also need a driver circuit, commercial ones tend to be a bit pricy, MERG does kits which are very easy to build and are much more economical.
You do need to budget a membership fee, but so long as you need more than one driver board it will still be worth it. Each board will operate 4 servos.
Regards
Keith
PS Steve got in first, NB the Servos also operate points very well!

DougN
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Re: Servo's for Signals

Postby DougN » Wed Feb 18, 2015 9:53 pm

I have used servo's from Hobbyking.com they send to the UK as well. The control circuits I purchased locally from Brunel models. I know that John will post to the UK. Last time I purchased one as a kit it was about $9 AUD or about 4.50quid. Not sure how this compares to MERG though. You do need to purchase a toggle switch for the signal and a power supply.
Doug
Still not doing enough modelling

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LesGros
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Re: Servo's for Signals

Postby LesGros » Wed Feb 18, 2015 11:18 pm

SG90 servos also available from The servo Shop at £3.10 or 4 for £11.60 and 10 for £27.50
see http://www.servoshop.co.uk/index.php?ar ... eat+Prices
LesG

The man who never made a mistake
never made anything useful

Stuart Barker
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Re: Servo's for Signals

Postby Stuart Barker » Thu Feb 19, 2015 10:36 am

Hi

Thank you for taking the time to respond to my post, and the excellent advise.
I am hoping eventually to build a reasonable sized layout so this really helps, and hadn't realised they can also be used for points.

Thank you once again.

Stuart

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Jol Wilkinson
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Re: Servo's for Signals

Postby Jol Wilkinson » Thu Feb 19, 2015 1:56 pm

Stuart,

more important than what servo is the question of which servo controller. Suppliers include MERG, Heathcote Electronics, Tam Valley Depot (available through Coastal DCC), GF Control, Micro Miniatures, Full Stop Signals and others.

The MERG is the least expensive but some of us have experienced interference problems with DC. Those, like the MERG, with a remote setting facility make life easier.

Jol

Stuart Barker
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Re: Servo's for Signals

Postby Stuart Barker » Thu Feb 19, 2015 6:16 pm

Hi Jol

Good point and timing. I have just started to look at the suppliers previously mentioned. Wizard offer a servo controller made by MSE(SM11) at £15.00, but it doesn't specify if it controls more than one servo. Have looked at the MERG site and they have a myriad of kits so I was planning on e-mailing them to get a price on which kit they recommend. Will also try the sites you have listed.

Many thanks

Stuart

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Penrhos1920
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Re: Servo's for Signals

Postby Penrhos1920 » Thu Feb 19, 2015 6:48 pm

Has servo twitch on been solved? Every layout I know that uses servos has had or currently has twitching issues. Personally I'm not convinced servos are as good as they are made out to be.
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grovenor-2685
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Re: Servo's for Signals

Postby grovenor-2685 » Thu Feb 19, 2015 7:01 pm

No need to contact MERg as you effectively already have by posting on here!
To advise on the most appropriate drivers it would help to know:
1. How do you intend to operate the signals, eg. from a switch panel or from a computer or ...?
2. How many points and how are they distributed over your boards?
Regards
Keith

PS. Twitching. This seems to come in two flavours:
1. Twitching on power up, which we believe has been largely eliminated by revisions made to the driver board and to the firmware.
2. Twitching caused by DC locomotives, usually in specific locations on the track, reported to be cured by fitting a capacitor across the track in the area where the problem is observed, the same sort of capacitor commonly fitted to motors in RTR stock for suppression purposes.

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pheald
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Re: Servo's for Signals

Postby pheald » Thu Feb 19, 2015 8:51 pm

Keith said:

"PS. Twitching. This seems to come in two flavours:"

For those of us not familiar what is twitching?

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stevecarr
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Re: Servo's for Signals

Postby stevecarr » Thu Feb 19, 2015 9:09 pm

Keith

Could you be more specific on the cures for twitching bearing in mind i am an electronic numbskull!

Thanks

Steve

RedDragon
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Re: Servo's for Signals

Postby RedDragon » Thu Feb 19, 2015 9:16 pm

Megapoints Controllers are another manufacturer for servo controllers, saw these at the last Warley and was particularly impressed. The GF Controls one mentioned by Jol I have seen demonstrated also and has a very good bounce action.

SteveT

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grovenor-2685
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Re: Servo's for Signals

Postby grovenor-2685 » Thu Feb 19, 2015 9:51 pm

For those of us not familiar what is twitching?

https://www.google.co.uk/?gfe_rd=cr&ei=JVnmVNihFcjH8gfJkYHgDw&gws_rd=ssl#q=rc+servos+twitching

Could you be more specific on the cures for twitching bearing in mind i am an electronic numbskull!

Not easy to take that further without knowing what sort of problem you are experiencing, a generic treatise would be rather long.
Regards
Keith

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Will L
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Re: Servo's for Signals

Postby Will L » Thu Feb 19, 2015 10:23 pm

Also Twitchy servos, symptoms and, eventually, solutions have been discuses here before.
http://www.scalefour.org/forum/viewtopic.php?f=26&t=2227

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grovenor-2685
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Re: Servo's for Signals

Postby grovenor-2685 » Fri Feb 20, 2015 11:29 am

Thanks Will, all the essential info is in that old topic. I didn't have time to look for it last night.
Regards
Keith

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Mark Tatlow
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Re: Servo's for Signals

Postby Mark Tatlow » Fri Feb 20, 2015 1:27 pm

Stuart,

You might find this helpful: http://www.clag.org.uk/tatlow-signalling.html. Going back through my Highland Miscellany thread either on here or my blog (eg http://highlandmiscellany.com/2013/02/0 ... nmutchkin/) you will see more of this kind.

Whilst these are mostly about making the signals, there is both a little on the servos and also on how I mount them on the signals. I am actually quite surprised others don't do it in the manner I do; I find it important to be able to take the signal out when required simply but to keep the joint as masked as possible.

To date, the servos that I have used are SG90s but I have started using something smaller but a bit more expensive. It enables me to reduce the size of the base a bit and get more servos stacked below whilst being in the depth of my boards. I have a 9 movement gantry on the workbench which I will post about in due course that will show these.
Mark Tatlow

ralphrobertson
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Re: Servo's for Signals

Postby ralphrobertson » Fri Feb 20, 2015 6:37 pm

Hi Stuart,

Since I wrote the article I may be able to help you here.

First though those photos make some of those signals look just awful, our Editor James has blown the photos I took up to something like a 400% size which shows all the warts which is not quite what I intended! Having said that I can at least make changes before they get finally installed in the months to come.

I have used SG10 servos but only for turnouts and not for signals. These are 3.7G servos and as I said in my article you can get them direct from China. A quick search on Ebay just now shows these available but there may be others. http://www.ebay.co.uk/itm/4pcs-RC-Sub-Micro-Servos-3-7g-High-Speed-Torque-Servo-rc-helicopter-airplane-car-/231462244293?pt=LH_DefaultDomain_3&hash=item35e4398fc5. The larger servos will not fit in the Plastruct channel whereas the 3.7G ones fit perfectly.

Hope this helps you in your choice.

Ralph

ralphrobertson
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Re: Servo's for Signals

Postby ralphrobertson » Fri Feb 20, 2015 6:42 pm

I should have added that the control is via the MERG CBUS Servo control boards which currently control most of our turnouts on Slattocks although we do still have some Tortoise motors. All the signals will be controlled from servos and in view of the size of the servos I decided to use these 3.7G's.

Ralph

Stuart Barker
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Re: Servo's for Signals

Postby Stuart Barker » Thu Mar 19, 2015 9:46 am

Dear all

Firstly I must apologies for not keeping up to date / replying to your postings.
Since my last posting I have purchased 10 x tower pro SG90 servo motors that have now arrived.

I have also just place an order with Digitrains for the OCT030 OCTOPUS III SERVO DRIVER, OCT031 REMOTE ALIGNER.
(Late last year I purchased all my DCC kit from them, they were really helpful as I was very new to DCC)
Having said that I had read an excellent series of articles in Scalefour News which I found very useful.

Anyway, once the servo driver arrives I will be able to have a play.

My layout is still very much at the early design stage, so nothing is finalised apart from the decision to go down the route of DCC with sound.
As guide I am using the book " An Historical Survey of selected LMS STATIONS layouts and Illustrations" Volume One

Thank you all once again for your assistance

Stuart


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