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Fulgurex point motor control

22526 Views 70 Replies 13 Participants Last post by  dwb, 
dwb
This week's project is to add control circuitry for a Fulgurex slow motion point motor. The photo below shows the parts I intend to use:


Those familiar with driving Fulgurex will probably think this is a bit over the top, but there is method in my madness and each component has its place in my scheme.

First, it is my intention in the longer term to drive the point motor via DCC, but there may be times when I don't want to have to go to the bother of addressing the motor via the control unit and then selecting the direction I want. To avoid that, I need a local switch. Some DCC point motor controls provide a facility for local buttons, but I'm not sure which those are and whether or not I will use them. In the meantime, I need to control the motor now because unlike Peco solenoids, you can't manually "flick" a Fulgurex. My solution to this need is to use a normally open, momentary action DPDT switch which can be seen in the left of the photo.

The momentary nature of the switch means that once the limit has been reached and the current is switched off, I can release the switch and there will be no current at all. This should avoid conflicts with any DCC control unit I install later. The drawback with this method is that I lose the switch acting as an indicator for the current setting of the point blades. The solution to this problem is to use one set of auxiliary contacts on the Fulgurex to drive the pair of LEDs which are also on the left along with the resistors and matching mounting bezels. This will provide a visual indication by the switch of the current setting. When DCC control is added, any changes caused by the DCC unit will be reflected by the LEDs. This circuit may also double up as input to a pair feedback sensors to provide PC control some time in the distant future.

The ceramic disc capacitor at the bottom of the photo is to provide a degree of noise suppression. According to LDT, the Fulgurex is rather "noisy" electrically and this is a good precaution. Once the motor is installed under the baseboard, I don't fancy lying on my back trying to retrofit these things later, so they're going in now.

The other two devices beside the capacitor are a pair of Zener diodes. This again is an LDT recommendation for reducing the voltage supply to the motor to reduce the change over speed. I'm doing this because the motor will be supplied at about 14v DC which is a bit on the high side.

I will be using the other pair of microswitch contacts to change the frog polarity on the point. The switch blades themselves are hard wired to the outer rails. This eliminates the potential for shorts should the microswitch change over before the moving point blade has ceased making contact with the outer rail. A short on an analogue DC layout is no problem, but it will shut down DCC which is not a good thing.

The black stringy stuff in the top right is heat shrink tubing which I will use to make sure there are no bare wires straggling about.

Now I just need to find something to mount the switch and LEDs on. Panel thickness is a bit of an issue for these LED bezels because the LEDs are quite small.

David
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dwb
Thanks for the compliments and the tips. I will certainly act on them.

I did wonder about whether or not to lay the tape first, but it seemed the easiest way to "break into" the problem. I was making it up as a I went along using my original plan as a guide. I have a suspicion that the adhesive on the tape will "cure" over a period of a few days or so. If it does then, with a steady drill the damage will be restricted to the immediate area of the hole. The bezels on the switches and LED holders should cover any frayed edges.

If it all goes pear shaped then there is still plenty of tape left on the reel to do the whole lot over again once the holes are drilled.

David
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dwb
>I bought a Clarke's bench drill for about £35.
Would that be the CPD5DD? Machine mart are advertising them for about £35 or so.

Regarding drilling holes. I have no training in metalwork and precious little experience either, so I would greatly value some advice.

After I have donned safety specs and gloves(?) and secured the panel so that it won't move, how do I go about drilling the holes?

The panel is 3mm thick aluminium. The LED bezels need a hole in the region of 3mm and it is possible that the hole will have to be "relieved" at the back since the bezel is designed for 2mm max.

The switches require a hole at least 6mm, and there needs to be a wee "ding" on the top surface for the locking ring key which prevents the whole thing from twisting.

David
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John Webb
David,
Drilling the small diameter pilot holes just rest the panel on a piece of 12mm to 20mm MDF board or plywood. Press down firmly to keep the metal panel from shifting with one hand and use the other to operate the drill. For holes 6mm or over use a clamp of some sort each end to hold the panel to the wood board. (The wood board supports the panel and stops the drill going into the table of the drill.) For holes over 10mm diameter I'd bolt the board to the drill table with countersunk screws and then clamp the panel to the wood.
It's also good practice with larger holes to check the drill is central to the pilot hole by lowering the drill over the pilot hole before turning the drill motor on.

DON'T WEAR heavy-duty work GLOVES when drilling - swarf can catch in gloves and if the hand slips and catches the rotating drill there is a real risk of the drill trying to drag the whole hand round. Light surgical type gloves are OK to protect against oil and dirt. Goggles (or impact resistant spectacles with side guards) should be worn - swarf can fly some distance. Regularly use a dustpan and brush to remove swarf etc from around the drill, workbench and floor in the area of the drill.

All holes drilled in aluminium will need a light deburr on the reverse side - a small ridge of metal is thrown up as the drill goes through. This ridge can be sharp and I don't recommend touching them.
The switch locking ring actually needs a hole or depression drilled to take the little down-turned bit on the ring, usually about 2mm diameter - measure the width to make sure.

It might be worth looking in a library or local bookshop for books on basic metalwork. (My knowledge comes from doing an O-level in 'Engineering Workshop Theory and Practice' about 40+ years ago!)

Regards,
John Webb

PS Yes, you are right about the Model number of the drill I bought.
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dwb
Thank you for the advice John, it is much appreciated.

David
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Makemineadouble
When you drill into thin section stock use small piece of emery paper between the drill bit and the work piece this stops it digging in and ripping, obviously you need a piece of soft wood behind the work piece as well.
Yes I know what I'm talking about I used to be a toolmaker..many years ago.
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dwb
Thanks MMaD


David
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dwb
A brief update...

boring, boring....

I didn't realise that there were quite so many holes.....

David
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5
While on the safety bit if you have any rings on your fingers take them off (if you can).
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Doug
More pictures please


Where are the switches? In line with the track on the point?

Are your LEDs all the same colour?
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dwb
>While on the safety bit if you have any rings on your fingers take them off (if you can).
I don't think my wedding ring will come off. I don't have any other rings. I try to work with my left hand close to the off switch. I have the panel clamped to the drill platform with a piece of scrap wood underneath. Once it is secure, I operate the lowering handle with my right hand very slowly.

The only damage I've done to myself so far is a small scratch from the "safety" visor that you drop down in front before drilling. I keep my safety goggles on at all times.

>More pictures please smile.gif
I'll post a picture of the panel when I've drilled the holes for the switches.

The switches will be "in place" on the panel. I've chosen centre off double throw switches. All the leds will be red.

I'm tempted to add signal controls and section occupied indicators but with 32 points at 4 connections per point, I think I've reached saturation point for the panel size. Of course if I decided to stick to "pure DCC / computer" control the panel would be un-necessary..


David
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dwb
The drilling has finished. I have "loaded" the panel with four switches and 8 LEDs. Here's what it looks like from the front:-


and here's the view from the back:-


I made the support brackets from "L" shape and plain aluminium strip I bought from B&Q.

Now I have to decide whether to drill any more holes "just in case" because once I start wiring it, that's it. The likely candidates are some LEDs to indicate section occupancy and some activation switches for electric uncouplers.

While I am pondering that, I'm going to work out how to arrange the rather large number of wires in a neat and orderly fashion

David
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John Webb
David,
I used a plastic spiral round the cables in my control panel (and underneath the layout) to keep them tidy - the spiral easily allows wires in and out and adjusts to different quantities of wire to keep them together.
Regards,
John Webb
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dwb
>I used a plastic spiral round
That's a good idea; I remember using it years ago at work.

David
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B
That's looking very good David, very professional.

One of the trade names for the plastic spiral is "Spirwrap". Easy to use & as John says easy to alter things or to add to at a later date.
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dwb
>That's looking very good David, very professional.
Thank you. It wouldn't pass close inspection though; some of the holes have wandered by up to 2mm.

David
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dwb
>very professional.
I should also mention that most of the appearance is due to advice given in this thread - I bought a Clarke drill press and an automatic centre punch to mark the position of the holes.

David
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dwb
I think I might drill a set of holes along some sections for some LEDs (maybe yellow) to indicate "section occupied". I think the Lenz LB101 module might be just the thing to drive this as it is a current sensor which delivers some kind of output when 1ma is detected flowing in the DCC supply. The only thing I don't know is, what kind of output is being delivered? It would be nice to know what volts and amps are involved. Does anyone know?

David
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dwb
I have drilled a set of holes which can be used as section occupancy indicators. I have also added four more switch holes and LED holes offset to the north east of the switch hole. These will be for electrically operated Kadee uncouplers. One side of the two pole switch will activate the relay which will allow the 3 amps needed by these brutes to operate. The other will send current through the indicator LED at the top left to show that the circuit is operating. I rather fancy blue for that.

Here's the state of the panel with the extra holes and most of the dirt cleaned off:


I have now started the process of installing the LED bezels, but I have run out.. I think I need another 100.

David
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B
Excellent progress David - it's going to look really good when lit up.
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dwb
>it's going to look really good when lit up.

The whole country will know because of the "brown out" when I switch it on


David
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