Megapoint - a simple way to control turnouts?

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Ian Everett
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Megapoint - a simple way to control turnouts?

Postby Ian Everett » Fri Dec 11, 2015 10:22 am

Has anyone experience of using the Megapoint system for controlling turnouts and signals using cheap servos? It looks to be very well thought through, cheaper and more effective than traditional point motors and simpler than setting up MERG etc. kits. It can be used with a traditional lever frame or (with an extra module) by DCC.

See http://loolee.org

Ian

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grovenor-2685
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Re: Megapoint - a simple way to control turnouts?

Postby grovenor-2685 » Fri Dec 11, 2015 12:07 pm

My experience is with MERG kits, which are pretty simple for this purpose and work well. A P4 modeller should have no problem assembling them.
The megapoints controller has some good recommendations but one or two issues to note.
1. To be cost effective you need to have 12 servos within reasonable reach of the board, anything more than 9 inches will need servo extension cables.
2. The actual setting up is quite tricky with a lot of counting LED flashes etc. You need good visibility of both board and the points/signals while doing the setup. Probably advisable to be able to connect up and complete the setup before fixing the board under the layout.
Regards

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steamraiser
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Re: Megapoint - a simple way to control turnouts?

Postby steamraiser » Fri Dec 11, 2015 5:44 pm

A S7 modeller friend of mine has given up on the MERG system and changed to the MEGA Points system.
He is looking to use the MP system to operate points, signals and uncoupling magnets.

He is of the opinion that the MP system is a lot more stable and is very well supported by the proprietor.
I understand that further operating options are being developed by MP.

Gordon A
Bristol

Alan Turner
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Re: Megapoint - a simple way to control turnouts?

Postby Alan Turner » Fri Dec 11, 2015 5:55 pm

steamraiser wrote:A S7 modeller friend of mine has given up on the MERG system and changed to the MEGA Points system.
He is looking to use the MP system to operate points, signals and uncoupling magnets.

He is of the opinion that the MP system is a lot more stable and is very well supported by the proprietor.
I understand that further operating options are being developed by MP.

Gordon A
Bristol


Well as a Scale 7 modeller who uses MERG products exclusively for the control of Ellerton Road I can assure those interested that the MERG modules are as stable as anyone else's.

Regards

Alan

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Jol Wilkinson
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Re: Megapoint - a simple way to control turnouts?

Postby Jol Wilkinson » Sat Dec 12, 2015 10:07 am

Alan,

I wish I could share your view.

I have used MERG servo controllers on the new signals on London Road and experienced various problems. I was attracted to them by the convenience of a remote control setting box, low cost and recommendations by several acquaintances and respected modellers.

Sadly I have found the MERG controller susceptible to interference (twitching) on DC powered locos and a "loss of initial position" memory when powering up (temporarily resolved by operating each servo's control switch). I joined MERG to buy the controllers and setting box but left after a year when it became apparent that there wasn't (at the time) a straightforward fix, despite the help provided by several MERG members and trying several software versions/upgrades. I also didn't wish to have to learn the language in which most of the articles in the news letter were written. It seemed to resemble English but I couldn't understand it.

Various "external" fixes for the interference created twitching have been applied, including shielded power supply and control feed cables, and mounting the units in aluminium boxes for shielding. The latest - a Tam Valley "No Buzz Inline Servo Quieter" - supplied by Kevin Dickerson at Coastal DCC - seems to provide a solution. I am therefore also going to try - again on Kevin's advice - a Tam Valley "Octopus" servo controller (don't you just love American product branding). This also has an optional remote setting box, although not as user friendly as the MERG unit.

The servo "throw" seemed limited by the MERG controller to about 80 degrees, which proved to be a problem with the LNWR rotating ground signals and one which I have yet to resolve.

It is disappointing that I couldn't get the MERG units to function satisfactorily. Inexpensive, small, easy to assemble, good r/c setting box. Having left MERG, I don't know what improvements may have been made.


Jol

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grovenor-2685
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Re: Megapoint - a simple way to control turnouts?

Postby grovenor-2685 » Sat Dec 12, 2015 12:36 pm

Jol,
The standard rotation for servos is nominally 90 degrees which the base level firmware provides for, some servos may not achieve this with the specified pulses, we have optional firmware that provides nominally 180 degrees which will allow any servo to achieve a full 90 degrees, the mechanical limits are usually a bit less than 180.
For interference from DC locos the most successful fix seems to be to fit small capacitors across the track in the area where the loco is when the problem occurs.
Since this is not the MERG forum perhaps take it off line and see if we can sort your problem.
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dal-t
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Re: Megapoint - a simple way to control turnouts?

Postby dal-t » Sat Dec 12, 2015 3:20 pm

I've not (yet) used servos, and although I'm attracted to the technology, reports of the sort of problems quoted by Jol have quite put me off. But I would also see the '9" from the board' proviso for locating servos as quite a severe limitation. By coincidence, I've just drawn out a 'fun' layout with 8 turnouts clustered very near the centre of one baseboard - but there are outlyers several metres away, and all a good deal more than 9" apart from each other. Glancing at more typical trackplans I can see few that would meet a 9" rule; even for a simple runaround loop that limits you to 18" (turnout each end, board in the middle) i.e. capacity for only a two-coach set. I know both turnouts to a loop can be linked and operated as one (let's not get into the pros and cons - I happen to be an 'anti') but that isn't the point, I want my servos to go wherever the track formation demands. Of course it wouldn't matter if boards were cheap as chips (which I presume is what they actually are, but again let's not go there ...). But at £50 a time I couldn't afford to litter them around, only working one or two servos each. Or have I misunderstood? I'm afraid it has been known ...
David L-T

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grovenor-2685
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Re: Megapoint - a simple way to control turnouts?

Postby grovenor-2685 » Sat Dec 12, 2015 3:26 pm

Boards are available to operate a single servo, the issue of cost effectriveness is with boards designed to drive 8 or 12 servos. The servo leads can be extended within reason, I have gone to about 3 ft without problems but I do seem to have been lucky so far as interference issues go.
Mind you, bear in mind that half a dozen people with problems, possibly self inflicted, make more noise than dozens without. MERG has sold hundreds of Servo control boards, many of them repeat orders.
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dal-t
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Re: Megapoint - a simple way to control turnouts?

Postby dal-t » Sat Dec 12, 2015 4:44 pm

Ah, enlightenment begins - thank you for that. I shall start checking the plan for my next major build to see how the turnouts might best (or most cost-effectively) be 'grouped'. Considering the other functions/adaptions it strikes me 90°rotation would be extremely useful for wagon turntables, the working of which I am currently mulling over, as well as for LNWR-style groundsignals. Regarding 'surge' interference, do I take it DCC eliminates the problem, or simply ameliorates/modifies it?
David L-T

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grovenor-2685
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Re: Megapoint - a simple way to control turnouts?

Postby grovenor-2685 » Sat Dec 12, 2015 5:22 pm

Regarding 'surge' interference, do I take it DCC eliminates the problem, or simply ameliorates/modifies it?

Difficult to be sure on these things when not experienced personally.
There seem to be several reported interference issues, that I have gleaned from the various problem reports and fixes.
1. Twitching of various types at start up, either inadequate power supplies or poor hardware or firmware design. The first is in the hands of the owner the latter two have been largely resolved.
2. Poor repeatability and similar problems in use, seem to be a symptom of poor quality servos, the SG90 in particular seems to have a lot of poor chinese clones.
3. Interference from passing locos, usually both location and loco specific, I have yet to see any report of this with DCC, it seems to be mainly an issue with kit built locos which have not been fitted with suppressors, suppressor capacitors on the track are reported to be a fix.
Regards

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stephenfreeman
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Re: Megapoint - a simple way to control turnouts?

Postby stephenfreeman » Sun Dec 13, 2015 9:06 am

Hi,

Yes the Megapoints board can be a little tricky to understand at first but is quite straightforward once you get the hang of it. I was fortunate in living not to far away from Dave and had a personal demonstration. It is more picky about it's power supply than others though. GF Controls is easy to set up but more expensive. The latest incarnation of Servo4/Sema4 works well.

For signals, the Megapoints system has possibly the best bounce simulation of the 3, then GF Controls, a close second, Sema4 does not IMHO give a good simulation without some tweaking of the code can be done.
Stephen Freeman
Bespoke Finescale Trackwork and Semaphore Signals 7mm to 4mm scales
https://www.tracknsignals.co.uk

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Jol Wilkinson
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Re: Megapoint - a simple way to control turnouts?

Postby Jol Wilkinson » Sun Dec 13, 2015 12:25 pm

stephenfreeman wrote:Hi,

The latest incarnation of Servo4/Sema4 works well.



It is perhaps regrettable that MERG doesn't take a leaf out of the S4 Society's book, and make some of their products available to non members. It might attract some to join.

As a former member, I don't feel inclined to join again to get the latest version of the Servo4, without the opportunity to try one.

Jol

junctionmad
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Re: Megapoint - a simple way to control turnouts?

Postby junctionmad » Mon Dec 14, 2015 11:42 am

Jol Wilkinson wrote:
stephenfreeman wrote:Hi,

The latest incarnation of Servo4/Sema4 works well.



It is perhaps regrettable that MERG doesn't take a leaf out of the S4 Society's book, and make some of their products available to non members. It might attract some to join.

As a former member, I don't feel inclined to join again to get the latest version of the Servo4, without the opportunity to try one.

Jol


It's £16 a year !!!!! , that's about the price of a good pub lunch, supplying to non members brings one closer to issues of commercialisation


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