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Fulgurex point motor control

22526 Views 70 Replies 13 Participants Last post by  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.

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Looking good David. Thats going to be excellent when finished.
Thanks for the encouragement. I'm going to order the remaining bezels, LEDs and switches tonight.

Plastic spiral opaque white coloured in two sizes can be obtained from any Maplins stores. Can easily be cut to desired length and threading cables through plastic spiral without bother or can be wrapped round cables.
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I've installed the first four LEDs. This is what they look like when they are all switched on (they've rather flared out on the camera, in real life they are a nice bright red) :-
Musical instrument Wood Line Metal Art

The rear of the panel looks like this:-
Machine Electrical wiring Cable Electronic component Auto part

The LEDs are all driven by external signals, so the anode has a resistor attached and then a long external wire which will end up on a terminal block somewhere behind the unit. The cathodes all go straight to 0 volts. I am using some copper coated paxolin strip left over from when I tried to make my own points many, many years ago as a bus bar. I don't know which is more disturbing - the fact I remembered that I had it, or that I was able to put my hands on it in about 5 seconds.

With this successful trial, it looks like quite a few evenings are going to be spent on the production line fitting LEDs.



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QUOTE With this successful trial, it looks like quite a few evenings are going to be spent on the production line fitting LEDs.

It will be worth it in the end.

Dose it get difficult using one colour of wire (orange)?

It dose look very impressive

QUOTE (dwb @ 6 Mar 2007, 22:26) <{POST_SNAPBACK}>I don't know which is more disturbing - the fact I remembered that I had it, or that I was able to put my hands on it in about 5 seconds.

I get very worried when that sort of thing happens to me !

The LED's look good & I like the idea of the copper strip for the common - the panel just gets better & better.
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On the control panal I made for my simple layout (well, compared to David's one) I use small squares of 'Veroboard' behind each LED. These squares are soldered to the LED leads and also hold the series resistor. The connecting wires go to the tracks on the Veroboard rather than direct to the LED. This gives greater mechanical strength and makes replacement easier if ever needed.

John Webb
>Dose it get difficult using one colour of wire (orange)?
I've just received Monday night's order and now have some red and black as well. I will reserve these for power and 0v.

For identifying the orange wires I have one necessity and three options:-

1) I must label every LED and switch on the diagram

2a) I only document the chocolate block connector terminals that will form the link to the layout. Then I wire each circuit in turn. Once complete the wires will be anonymous.
2b) I write the LED / Switch number on a small seld adhesive label before sticking it into the documented terminal strip. I have done this in the past but my number writing can be patchy and in time the adhesive fails so the labels fall off
2c) I use cable markers to identify each circuit. I already have a set of markers for larger wire from when I set up the main supply buses around the layout. So long as they don't fall off before I get them attached to the terminals, they should be ok.

That's an interesting idea. I don't think I have space for that at this stage. However if this panel works, there will be two more to build and I will throw that idea into the mix - I like variety.

I'm going to wire up one of the blue LEDs tonight because I want to see what it looks like
(and also because the red LEDs were short shipped).

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Check out my control panel. Hi-tech marvel that it is. Very cheap too. More info in my Blog...

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>Check out my control panel
I see you'be already solved my "problem for the day" - how to mount the panel to the baseboard

My third switch, the one on the right, controls two points on a crossover. If one is set for the crossover, the other has to be as well or else it will cause a derailment. So both cross or both are straight.

After spending more hours under the baseboard, I have proclaimed to the heavens that there has to be another way. I will be contemplating long and hard about coming up with a better way of securing the point motor and wiring up all the connections.

If I draw up a control panel template on the PC, how can I transfer this image to a sheet of metal? Is there some sort of photo etching method...?
>If I draw up a control panel template on the PC, how can I transfer this image to a sheet of metal? Is there some sort of photo etching method...?

You're now getting into the phsical side of CAD and I have very little experience here. The closest I can offer is PCB design where one of the outputs is a "Gerber plot file" which is sent to the PCB house to drive the hole drilling machine. I am sure there are some on the forum who may know what you are looking for. If you don't get an answer in this thread, I would suggest starting a new one so that everyone gets to see it.

When I printed my panel, it came out about half size. As I had drawn a grid round the edge, I was able to do the same with the panel. After a little bit of phaffing about it came together quite nicely. Using the car lining tape helped a lot.

I am really pleased with my choice of a 6U 19" rack blanking panel. It's 3mm thick aluminium and really solid so it is able to act as a structural member in the frame I have constructed to support it. I've also worked out how to get 180 connections onto the frame with all screws accessible. I'll post some photos when I'm done, but since I haven't got any m3 bolts and nuts, you'll have to wait a few days.

Good luck.

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To Doug re panel production:
The method used will depend on the size of your panel. If you only have an A4 sized printer, you will need either to limit your panel to A4 or your drawing or DTP program will need to be able to print out a larger sheet onto several A4 pages.

You could either simply stick the pages down onto the metal panel or the following might work.
Print out onto Overhead Projector Transparency sheets with a negative image - ie the 'track' is clear and the background black.
Photo-resist spray the panel and arrange the printed OHP sheets on it and expose to light as per the Resist instructions.
Develop etc. This should leave you with photo-resist on the background and the tracks clear. Now paint over the tracks with whatever colours you want.
Clean off the unwanted paint and photoresist which should leave you with a clear metal background.

Please note this is all theoretical - I have not tried it myself!

Another route is to find someone with silk-screen printing techniques and use that process to transfer your layout onto the metal panel.
John Webb
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Another way may be to use Xtracad and print that onto A4 as by the time you have it to fit on an A4 sheet it will look like a single line anyway and then use that as your template.

>my "problem for the day" - how to mount the panel to the baseboard
I have now resolved this one. It doesn't have quite the style of Doug's method, but it works for me

Wood Font Rectangle Art Parallel

The panel hinges forward so that I can get at the insides:-

Wood Rectangle Indoor games and sports Electronic device Toy

I have now dismounted the panel so that I can wire it up in comfort:-

Rectangle Font Gas Wood Electronic instrument

If you look closely at the mounting frame, you will see 3 strips of 5 chocolate block connectors, each with 12 connections. I think that's just about enough for the 32 points and miscellaneous section occupancy indicators.



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That Looks great David
How much has it cost you so far David?

It's looking really good David. Like the way you have mounted it so that it is easy to work on - much better than lying underneath or having to bend over something.

Can't wait to see it all lit up !

Thanks for the update & pics.
>How much has it cost you so far David?
about £134. The major cost items so far have been the front panel - £23 - and the DPDT momentary center off switches. The ones I am using are pricey at about £3.75 each. I've still another 20 to get. Next is the LED mounting clips at £16.50, the LEDs themselves and their resistors come in at about the same cost and then the connector blocks at around £14 for the 15 you see attached in the photo. It is a lot of money when added up, but I've been placing orders for about £30 a time, about once every two to three weeks. So spread that way it is much more affordable. I bought the connector blocks last October.

The "expendable" items in this project are the front panel and the car lining tape. Everything else can be reused though whether it would be worth recycling the LEDs or not, I'm not sure.

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Looking good.

I have found some cable with 8 bound wires 0.22mm² that will go to each point. Power will come to the panel and the wires will take power to the point and send back switch status to the LEDs. I was using Ethernet cable, this new one will hopefully be a little easier to manage.
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