Looking good David. Thats going to be excellent when finished.
Fulgurex point motor control
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:
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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
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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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.
David
The rear of the panel looks like this:-
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.
David
Attachments
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.
David
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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David
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.
3
>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.
>Veroboard
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
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(and also because the red LEDs were short shipped).
David
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.
>Veroboard
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
David
2
>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.
David
I have now resolved this one. It doesn't have quite the style of Doug's method, but it works for me
The panel hinges forward so that I can get at the insides:-
I have now dismounted the panel so that I can wire it up in comfort:-
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.
David
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