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BritMod OO Challenge (The Dave Competition) - Devil's Bridge


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Some messy wiring occurs:

 

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Despite my small mountain of electronic components I have, I don't have any 40k resistors needed to get the voltmeter to read on the correct scale so just ordered some from ebay (the meter leg closest to the camera with the blue and white wire wrapped around is where it should connect).

 

The choc block on the left is for attaching a seperate power supply for when using the DCC bus isn't an option. I work in DC still so I'd need that anyway, but it means if this idea doesn't work then it won't take much to convert it to a more conventional setup. 1 of the toggle switches is for selecting which supply source to use.

 

DCC bus still needs adding under this board and boards 1 and 3, and this board still needs some droppers from the sidings.

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The work listed above has been carried out last night and this morning, so.......

 

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All 3 boards in a nice big 90 degree corner format :) look carefully and you can see the voltage needle sat in the middle of the Farnell supply at the far end and the needle sat in the middle of the meter closest to the camera. The meter is attached to the track proving the bus works along it's whole length and there's no crossed polarity.

 

The boards are being held together by clamps as per the Dave standard and my test dutch 37 over on the far board has been doing succesful lengths of the whole track under it's own power (is this the first thing running across independent modules using the Dave standard?) and into each siding on board 2.

 

Next job is to level the track/boards on board 1, there's far too much undulating going on each side of the bridge, the VGA in the picture was uncoupling itself each time it got to those sections. I need to dig out an AC power supply to test the point control system properly, however I have been able to lable the switches with the DC supply connected so it can be tested properly when completed :)

 

Useful notes to others building modules, having more than 1 module makes it easy to check whether the rail ends are at 90 degrees to the board end and whether the rails get close enough to the board ends. This is the first time these boards have been set up in this orientation and it showed that on 2 of my ends the rails were too far back and needed a little tweak for smooth running. Everything was at 90 degrees though so I'd got that right at least :)

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Well, all work and no play makes Satan a dull boy. So I took a walk with the dog at sun up this morning down to the road bridge over the railway at Devil's Bridge Curve which was offering a nice view up and down the line today (is it just me or does this place feel like it's laid out different each time I visit?)

 

The line is usually fairly dull, DMUs plodding up and down all day, but first thing in the morning is when the daily speedlink passes through and occasionally shunts the nearby sidings. We don't have long to wait before we hear the first DMU of the day coming from the east, which as a bonus is towing a CCT with the days newspapers in:

 

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Next, the freight is also due from the east, but an unexpected noise can be heard in the opposite direction and we're in luck! There was a possesion last night and the engineers ballast train is only now returning:

 

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Not much longer and another 37 can be heard, line regular misappropriated onto RfD turns 'Ripple Lane' appears over the river slowing down with the morning speedlink. At least more than 50% of the train is tankers so it's not too far removed from it's usual duties!

 

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We're in luck as it's come to a stop just after the bridge and get to watch as it collects the VGA before carrying on:

 

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The dog's getting a bit bored now so it's time to head home. The scenery's looking a little bland around here, somebody really should look into that.....

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Electrickery a flowin', points be a throwin'......

 

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......As long as you don't want to throw more than 1 point every 2 minutes! But proof of concept has worked, CDU charges drawing less 5mA from the bus and is able to throw a point. Metering on the rails show no effect or spikes on the track voltage. It doesn't completely drain the CDU each time so tomorrow's test with a cap 250x larger (and 250x longer to charge in the current set up (that will be resolved!)) hopefully will allow multiple throws before running out. Watch this space.....

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I guess the key thing is how long does it take from initial plugin until it becomes "useable".

 

It may make a difference as to whereabouts it goes in a modular setup and how soon it gets to a point where power can be connected to the board - unless it has its own power supply until then but that rather defeats the whole point of having the "integrated" power supply!

 

The standards do, of course, say that all point and accessory control should be completely independent from the main track bus in case a point shorts and knocks everything out, then you can't change it ... so I'm not sure what would happen in the event of that happening.  Or if they're Peco I guess they could just be changed by hand? (that wouldn't work with my Minx motors - but then again, they do have their own power supply).

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Initial report from adding bigger cap:

 

For a start, input resistance has been reduced for a quicker charge time (Ammeter is now x30 (still, drawing less than 20mA overall from the bus) and can recharge the CDU alone in about 10 seconds (10 seconds between point throws rather than 2 minutes)).

 

Big cap is currently connected 'unprotected' across the voltmeter for testing. Charge time is very long! However, it was up to about 8 volts after 15 min and I accidently knocked a point switch......enough power at low voltage to confidently throw a point! (Needs at least 16v on just the CDU) so that's a good start.

 

once this testing phase is done, the next phase will be to add a low value/high current resistor to the + side of it (then possibly a diode too depending on effectiveness) then attach it to the caps on the CDU. The theory being that the CDU alone charges much quicker for regular throws and the extra resistor will make the big cap charge slower but keep the CDU topped up for multiple throws in a short space of time in the long run.

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I guess the key thing is how long does it take from initial plugin until it becomes "useable".

 

It may make a difference as to whereabouts it goes in a modular setup and how soon it gets to a point where power can be connected to the board - unless it has its own power supply until then but that rather defeats the whole point of having the "integrated" power supply!

 

The standards do, of course, say that all point and accessory control should be completely independent from the main track bus in case a point shorts and knocks everything out, then you can't change it ... so I'm not sure what would happen in the event of that happening.  Or if they're Peco I guess they could just be changed by hand? (that wouldn't work with my Minx motors - but then again, they do have their own power supply).

on the last 'point', any issues with it and the switch on the left completely isolates it from the DCC bus.

 

I probably interpreted it wrong, but with it being DCC I partly assumed the 'independent from the bus' was refering to using decoders to control points from handsets. Hence why 'current draw by an LED' levels (how many have lights in their loco's?) For any module extras seems reasonable and wasn't mentioned in the standards. As long as it doesn't interfere with the DCC signal I'll consider it a win.

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Of course, I think the thought behind "independent" was actually if you use DCC to change a point and there is a short, you then can't re-energise the bus to change the point and fix the problem.

 

Using Peco or similar "thump" motors of course you have the "move by hand" option (assuming you know which one it was that caused the problem...) but if you are using a slow action point motor that can't be adjusted by hand, then problems may occur.

 

Despite earlier explanations of plunging villages into darkness, exploding transformers and setting fire to things, you seem to have this well thought out and certainly in concept form everything seems to be working exactly as designed.

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Of course, I think the thought behind "independent" was actually if you use DCC to change a point and there is a short, you then can't re-energise the bus to change the point and fix the problem.

 

Using Peco or similar "thump" motors of course you have the "move by hand" option (assuming you know which one it was that caused the problem...) but if you are using a slow action point motor that can't be adjusted by hand, then problems may occur.

 

Despite earlier explanations of plunging villages into darkness, exploding transformers and setting fire to things, you seem to have this well thought out and certainly in concept form everything seems to be working exactly as designed.

Yes I do enjoy scaring people (tbh, when dealing with high voltages those are regular occurrences in some situations) I'm even debating getting a spare digital V meter I have to attach to the big cap just for you to make it look more like a bomb ;)

 

Report @ 16v and still charging: able to do at least 4 throws back to back before losing too much energy. I suspect if I was using push buttons or electric pencil operation methods it would be more as the old Hornby passing contact switches I'm currently using make 2x contacts on each throw which unnecessarily uses 50% more power than required each time.

 

Edit: as suspected, @16v using electric pencil method = 9 back to back point throws :) Now onto the next test then.....

Edited by Satan's Goldfish
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Here's a button to scare you cromptonnut ;)

 

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It's a bit of a misnomer really, it'd only draw 1A from stone cold empty. Pressed when partly charged my maths still puts it's draw at less than a modern rtr loco.

 

Anywho, here it is all properly connected to the CDU, the 7.5 ohm resistor means that when a point is thrown the PM draws from the CDU, then after that the big cap tops the CDU back up fairly instantly. So 1) no massive cap connected directly to the CDU or bus, and 2) when an auxilary supply is used current draw is limited when the capacitor is empty.

 

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As already stated, I'm not happy with the Hornby switches, but for this set up enough point throws can happen between recharges for the small amount of occasional shunting the yard would see. For bigger installations (Narwich modules) less energy inefficient switching methods will be used, and I'll do some proper investigation on what is an acceptable current draw on the bus from empty. The level of current draw this is set to is incredibly low really.

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Some colour (I'm not predicting much scenery before the meet) and some more posing of stock. With a limit of 2 trains at the meet I'm trying to get a feel for what I think works best with my modules.

 

MGR snakes quite nicely around the curves:

 

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Loco hauled passenger stock. A 7 carriage train should normally seem a big prospect but it looks small on the modules to me:

 

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Mixed freight.......well that's most likely going to be 1 of the 2 trains anyway, just got to work out which wagons and 37 I want to use. Testing an unfitted rear here:

 

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As can be seen on some of the pics I've started painting the sides black IAW the uniform recommendation. Currently trying to find the motivation to visit my spider infested garage to make sides for the bridge module so that can look a little neater.

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  • 2 weeks later...

SG, can I just check one thing please?

 

Are each of your three boards "independently legged" and to standard, or are they all supported off the centre board and one module made up of three boards?  It's just the way I have the modular meet set up at present has your three boards in different areas of the arrangement so I wanted to make sure that I didn't have to actually put all three boards adjacent to each other?

 

Whether it's a good idea or not I can't make my mind up yet but I've done my best to "break" the modular system by having everyone's individual modules apart from their others so that we can check wiring, height and other compatibility as much as possible.

 

Whilst set up as above it's very impressive, I'm just looking at the various options - it may end up "as one" yet anyway...

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Hey Nut,

 

They are 3 completely independent seperate modules each with their own legs. They don't have to be beside each other.

 

I did put on the forms that I was going to drill through the end plates to be able to bolt my modules to each other rather than using clamps, but I never got around to that.

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Excellent, that does help with flexibility considerably.  Just don't forget to buy those clamps...

 

At the moment your "sidings" are on the single track end of Hailsham, with my 'buffer stop' on the end to stop trains falling off.  The 90 degree curve is top right after a 10ft long straight section out of the fiddle yard, then Badgers Vale as a short straight section then your LH s bend before the junction.

 

It'll all make sense when the plan arrives, honestly!

Edited by cromptonnut
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  • 1 month later...

A successful first meet for the 3 Devil's Bridge boards, work will now continue on them for scenery.

 

A couple of things I've learnt, the uncoupler ramps I'd got for the sidings weren't quite what I thought they were! But following what I've seen today I think the sidings will be better served if they're Kadee friendly instead. Also, point control for shunting in modular mode is much simpler using mk1 finger!

 

Following the Shillingstone example, I'm going to create a couple of 'end plates' so I can store and transport the sidings and the bridge boards face to face. As well as making them easier to handle, it will also help protect scenery.

 

The curve......... I really need a bus for the bridge.

 

Looking forward to the next Dave meet :)

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  • 4 months later...

Sad days, due to space limitations in the garage and other project priorities, the 3 Devil's Bridge Dave modules will be deconstructed. The 2 Hornby river bridges were also damaged in the house move. The track is all salvageable along with the electrics, and the legs are going to be reused on a new project (which may have some Dave compatibility built in, final design isn't ready yet).

 

It's been an enjoyable experience, a straight Dave board that's easier to store may be in my future if there's still life in the concept down the line.

 

THAT IS ALL

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Sorry to hear of the damage - but we haven't yet finalised a date for our 2016 meet so you have plenty of time for something else :)

 

Remember that as long as the ends are Dave'd, what's in between generally doesn't really matter.

 

Looking forward to hearing your exploits on your next projects.

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  • 3 weeks later...

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