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Author Topic: Longframlington (Northumbrian branch line)  (Read 56006 times)

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Offline DaveGlew

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Re: Longframlington (Northumbrian branch line)
« Reply #375 on: April 09, 2018, 08:16:05 AM »

Uncouplers - I need to replace the two under-track permanent magnets with the servo-driven hinged flaps that I have been working on.

Hi Richard, would you be able to post a picture of these please.? I'm about to drill holes for a bunch of electromagnets but before I do so, I'm keen to see what you have done - particularly as you are moving away from magnets. Thanks
Dave
If it looks right and it works then I'm happy.

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #376 on: April 09, 2018, 09:03:30 AM »

Uncouplers - I need to replace the two under-track permanent magnets with the servo-driven hinged flaps that I have been working on.


Hi Richard, would you be able to post a picture of these please.? I'm about to drill holes for a bunch of electromagnets but before I do so, I'm keen to see what you have done - particularly as you are moving away from magnets. Thanks
Dave


It's here: http://www.ngaugeforum.co.uk/SMFN/index.php?topic=22058.msg500625#msg500625

There is a short video on the next page.  Make sure the hinge is brass, not brass-plated steel. Ignore the big hole in the baseboard, that is just a legacy of previous experiments.  You will need to cut away a recess for the magnet to swing into, but if you are careful this can be done from underneath without cutting through the top of the board or disturbing the track.

Cheers, Richard
« Last Edit: April 09, 2018, 09:06:09 AM by belstone »

Offline DaveGlew

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Re: Longframlington (Northumbrian branch line)
« Reply #377 on: April 09, 2018, 09:15:03 AM »
 :thankyousign:
Thanks for sharing Richard, that looks like a properly engineered solution  :beers:
If it looks right and it works then I'm happy.

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #378 on: April 09, 2018, 10:44:51 AM »
:thankyousign:
Thanks for sharing Richard, that looks like a properly engineered solution  :beers:

Over-engineered more like - you could probably use it to uncouple full-size wagons. But the flap hinge does need to be quite heavy so it falls away under its own weight, which means you need a big servo to lift it up. Just 'cos it's N gauge doesn't mean the hidden bits need to be tiny as well.  But there again my layout has welded Dexion baseboard frames so you might argue that I tend to make things a bit stronger than they need to be...

Richard   

Offline kirky

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Re: Longframlington (Northumbrian branch line)
« Reply #379 on: April 10, 2018, 08:25:52 AM »
:thankyousign:
Thanks for sharing Richard, that looks like a properly engineered solution  :beers:

Over-engineered more like - you could probably use it to uncouple full-size wagons. But the flap hinge does need to be quite heavy so it falls away under its own weight, which means you need a big servo to lift it up. Just 'cos it's N gauge doesn't mean the hidden bits need to be tiny as well.  But there again my layout has welded Dexion baseboard frames so you might argue that I tend to make things a bit stronger than they need to be...

Richard   
Good god, the whole mezzanine floor at our club is held up with Dexion which has about five layouts on it and often twenty fat blokes. Definitely over engineered.
Cheers
Kirky
Northallerton will make its next public appearance at the LINCOLN MODEL RAILWAY CLUB ANNUAL EXHIBITION Feb 29th -1st Mar 2020



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Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #380 on: April 10, 2018, 02:13:34 PM »
The original plan was to do the frames in welded aluminium U channel (I prefer metal to wood in general) but I would have had to farm out the fabrication and I was too impatient to wait.  These boards are outrageously heavy, I won't be making any more like them.

Richard

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #381 on: May 13, 2018, 08:59:54 AM »
Dear old Longfram is back.  It never really went away, but has spent the last month languishing under the dining table while I fiddled around with coupler designs. This kind of treatment is not good for a layout, but the only casualties appear to be a couple of chimney pots.

The last time I did any work on it I pulled out almost all the electrics to start again.  So the first thing to do was sort out a control panel.  With it being a small layout (four turnouts) I had the idea of building the controller, turnout and uncoupler operation into a single handheld box.  So I ordered a load of bits, and this is the result.





The controller is an old AMR unit which were well thought of in their day.  It will be interesting to see how it performs compared to the Gaugemaster I was using before.  Four toggle switches on the front for turnouts (like a very small lever frame) and two thumb-operated pushbuttons for the uncouplers.  All housed in a metal enclosure with a 15 pin Sub-D chassis mount socket firmly bolted to it, connected to the layout using a VGA cable.  I have no idea whether the cable will handle the current in/out on the controller, all the switches are carrying only signal loads for the servo boards so they will be fine. I have read that VGA cables are rated somewhere between 300ma (marginal) and 1A (no worries) but haven't found a definite answer.

Having got the control unit built and circuit tested, I set about fitting servos to the three turnouts on the station throat complex and the uncoupler beneath the level crossing.  No problems there, using the same mounting system as the one I fitted to the other end of the layout.  I then started connecting everything up: I now have eleven wiring colour codes which isn't quite enough (I need another colour for frogs, and green is taken already) but should give me a fighting chance of diagnosing faults in a couple of years time when I have forgotten what I did in May 2018.



The attachment for the 15 pin socket is a temporary lashup, I will probably bolt it to another metal enclosure for rigidity.  I want everything to plug in from underneath, no wires and plugs sticking out of the sides. The wiring needs a bit of tidying, a few cable guides to stop stray wires getting caught in the servo arms, but meanwhile I found I had a problem of my own making.

On my previous layout I used small signal relays for frog switching.  They are cheap and reliable, much less fiddly than microswitches, so I thought I would so the same here.  Unfortunately I had a blonde moment and didn't think enough about the way that the servo switching works.  So I now realise I don't have a 12v feed to trigger the relays.  I poked around the servo board with a multimeter and found that each servo switch has the feed side at +5v when off, 0V when on.  A bit of Internet research suggests that I can use that as a signal to switch the corresponding relay using a very simple transistor circuit, hopefully without interfering with the actual servo operation. I will order some bits.

So I only managed to get trains running in a straight line from fiddle yard to baseboard edge.  It's a start anyway.  The uncoupler works fine, and so do my "Poundland Tortoise" slow-action turnout motors. For now the coal merchant will have to unload his delivery at the station throat: these wagons aren't going any further until I get the second board wired up.



Richard

Offline kirky

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Re: Longframlington (Northumbrian branch line)
« Reply #382 on: May 13, 2018, 09:37:20 AM »
Dear old Longfram is back. 

 :claphappy: :claphappy: :claphappy:

Thats looking very interesting indeed Richard. Love the idea of a lever frame within your handheld - ingenious
Im really happy Longfram is back.

Cheers
Kirky

Northallerton will make its next public appearance at the LINCOLN MODEL RAILWAY CLUB ANNUAL EXHIBITION Feb 29th -1st Mar 2020



Layout: Northallerton: http://www.ngaugeforum.co.uk/SMFN/index.php?topic=1671.msg16930#msg16930

www.northallertonngauge.co.uk

Cleveland Model Railway club website: www.clevelandmrc.club

Offline Newportnobby

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Re: Longframlington (Northumbrian branch line)
« Reply #383 on: May 13, 2018, 10:32:31 AM »
Aaaargh! More scary pics of wiring but I have to say that hand built controller is a great idea and looks superb.

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #384 on: May 13, 2018, 09:32:10 PM »
Day 2 of the Longframlington Big Weekend, and I can now run a locomotive from one end of the layout to the other (although only in a straight line until I get the frog switching sorted).  The main job was installing the second flap-type uncoupler which sits roughly level with the end of the bay platform.  This also happens to be where the crossmember for the baseboard frame is - not a problem with the old permanent magnets which were buried in the trackbed and the track laid over the top.  I didn't want to dig the track up to remove the old magnets, so I had to do it from underneath, which meant cutting a section out of the crossmember.  This, like the rest of the baseboard frame, is made from welded Dexion.  It isn't often you see someone working on their layout using an angle grinder.



With the offending bit of steel out of the way I used a carbide milling cutter (Chinese bargain) in the minidrill to excavate around the magnets until they could be extracted with pliers, rather like pulling teeth.  The new uncoupler is exactly the same as the one under the level crossing, powered by a big chunky old-fashioned servo which should be more reliable than a little baby one. Due to laziness I bought some laser-cut plywood servo mounts rather than making them myself (the uncoupler servos have to be mounted sideways) and I am more than happy with those.

The two servos on the station board are controlled by a Heathcote control board which is actually mounted on the other board, with long extension leads to the servos.  That reduces the number of connecting wires between the two boards, a five pin DIN plug and socket does the job nicely.  The other job I did was to put a DPDT reversing switch in between the controller and the power feeds to the track.  This is tucked away under the baseboard, and means that the direction switch on the controller can be made to correspond to the direction of travel of trains, whether the layout is being operated from in front or behind.  Oh, and I made up a proper bracket to support the 15 pin plug for the control box lead, and used about half a bag of cable ties to smarten everything up a bit.



"Smart" in this case is a relative term, but I can live with this level of rats-nestery.  OCD I am not. Apologies to @Newportnobby for yet another scary wiring photo, almost the last I promise.

Richard

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #385 on: May 15, 2018, 11:36:27 PM »


Today's post brought a padded envelope full of cheap electronic components, and what you see here is the test prototype for the frog switching units.  It uses a 2N4401 transistor, a diode and a resistor to take the 5v signal from the servo control board and use it to operate a 12 volt SPDT relay to switch the frog polarity at the same time that the servo moves the point blades, and using the same on-off toggle switch. 

The circuit diagram I used was for a 24v relay and I had no idea how a transistor worked.  It specified a 4.7K resistor in the signal input line.  I found that although the relay engaged smartly it was very slow to disengage, and the servo board was making a faint humming noise.  I took a random guess that the resistor value was incorrect, added a second resistor in series with the first, and the result was better but still a bit slow.  So I hunted through my big box of electrical junk, found a 100K variable resistor (out of sight in the photo), plumbed that in and discovered that the relay worked fine at around 14K resistance.  So I will get busy with Veroboard and soldering iron, and should very shortly have a fully working layout again.

The ability to operate a relay in parallel with a servo is a handy little trick, opening all sorts of possibilities for interlocking, automated signalling etc, and the components cost buttons.  I love this hobby: before this evening I had absolutely no idea what a transistor actually did. Now I have made one do something that I can understand and have a use for.

Richard

Offline Newportnobby

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Re: Longframlington (Northumbrian branch line)
« Reply #386 on: May 16, 2018, 09:47:22 AM »
I was fine up until "It uses...." on the second line and then you lost me completely :dunce: :-[

Offline Papyrus

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Re: Longframlington (Northumbrian branch line)
« Reply #387 on: May 16, 2018, 11:52:35 AM »
I was fine up until "It uses...." on the second line and then you lost me completely :dunce: :-[

Wot 'e said...  :confused1:

Chris
"As I always say, it's a funny old world. Do you always say that? Oh good." (Jill Tweedie)

Offline belstone

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Re: Longframlington (Northumbrian branch line)
« Reply #388 on: May 16, 2018, 01:11:02 PM »
I have always regarded electronics with deep suspicion, and I still can't quite believe I am dabbling in this kind of witchcraft.  But it's all about reliability: if I didn't use relays to switch the frogs I would have to use microswitches, which are much more fiddly to set up and easily knocked out of adjustment. It's all harmless really.

Richard

Offline Mito

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Re: Longframlington (Northumbrian branch line)
« Reply #389 on: May 16, 2018, 08:52:14 PM »
At first glance at the photo I thought you'd pinched one of my spaghetti photos! Do you have a wiring diagram for this? I'm liked you, I find electronics difficult but something like this I could possibly manage, I think ???
You know you're getting older when your mind makes commitments your body can't meet.
https://www.ngaugeforum.co.uk/SMFN/index.php?topic=40567.0 125x60 and a bit.
https://www.ngaugeforum.co.uk/SMFN/index.php?topic=24101.0 Off on a journey

 

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