Brimsdown-The last grand project.
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Will L
- Posts: 2524
- Joined: Sun Jul 20, 2008 3:54 pm
Re: Brimsdown-The last grand project.
Back in the day when peole were a great deal less fussy about fitting realistic tie bars to points I too had switch blades solder to a PCB stretcher/tie bar. The solder joint was indeed inclined to fail. The solution was to reinforce the joint with a little L shaped piece of thin metal strip. I used 5 thou phosphor bronze strip which I also used to make pickups at the time. Sides of the L no more than 1mm vertically and 2mm horizontally and the strip no wider than the PCB tie bar. You can barely tell they are there in among the solder and they can be relied on. I can't say I never had one fail, but I don't remember it happening. It was certainly not a regular thing which the plain solder joint failing was.
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PhilipT
- Posts: 44
- Joined: Thu Mar 05, 2015 4:18 pm
Re: Brimsdown-The last grand project.
A simple but highly effective alternative was described by Mike Norris in SNews a few years ago using vertically mounted pcb with 0.45mm brass wire soldered to the switch blades. It is not difficult to make, is reliable and unobtrusive. Where he used 1mm thick pcb, I use 0.6mm material which is more than adequately strong. I have also used 0.4mm stuff but gapping it while retaining strength is a bit fraught, hence the 0.6mm which I believe is obtainable from Hobby Holidays.
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Tony Wilkins
- Posts: 818
- Joined: Tue Mar 20, 2012 3:57 pm
Re: Brimsdown-The last grand project.
PhilipT wrote:A simple but highly effective alternative was described by Mike Norris in SNews a few years ago using vertically mounted pcb with 0.45mm brass wire soldered to the switch blades. It is not difficult to make, is reliable and unobtrusive. Where he used 1mm thick pcb, I use 0.6mm material which is more than adequately strong. I have also used 0.4mm stuff but gapping it while retaining strength is a bit fraught, hence the 0.6mm which I believe is obtainable from Hobby Holidays.
Hi Philip.
I seriously considered using those or something like it for my layout. However as I didn't really want the tie bar on edge, for several reasons, I elected to go for the 'simple' solution for the hidden sidings. Plan B is that if their reliability proves unsatisfactory, I will replace them with a modified design as they fail. The desire to get enough track down to be able to run something being the overriding factor. For the scenic turnouts I will be using a combination of Mike Norris's design and the old MRSG / Studiolith wire in tube type utilising Exactoscale Tortoise mounting plates modified to fit the Cobalt motors. I have already successfully fitted something similar, but with Tortoise point motors to the EMAG (ex NAG) group layout. I will post details in the not too distant future.
EDIT: the pcb I am using is approximately 0.75mm thick x 2.0mm.
Regards
Tony.
Inspiration from the past. Dreams for the future.
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Tony Wilkins
- Posts: 818
- Joined: Tue Mar 20, 2012 3:57 pm
Re: Brimsdown-The last grand project.
What follows is pretty mundane stuff, but may be of interest to some.
Dropper wires.
The method I use dates back to my involvement with the North London Group's layout Heckmondwike and has been successfully used on Bodmin and my layout Green Street. The golden rule is a minimum of two dropper wires per length of rail or rail section (crossing or switch). This is to build in some redundancy and increase reliability. If one joint fails, and they do, things will continue to work. Only when both fail do things stop and then there will be two joints to mend, but less often.
I use 22 swg tinned copper wire for preference. A batch of wires are cut to length (never enough) and the end 2.5 - 3mm bent at right angles to the rest.
Holes are drilled through the base board next to the outside of the rail, being careful not to mark the head of the rail. A small piece of scrap plastic drilled through and placed against the chuck can serve this purpose. My drill features a hexagon quick release system (sometimes known as Snappy) and I have some drills with quite a smooth face to the holding piece. I previously used a 1mm drill for this job, but as the smallest drill in the set was 1.5mm, I have used that instead and has the advantage of being longer.
After inserting the dropper wires into the holes, the end of the wire is pulled up and the last 5mm or so of the vertical part is gently bent inward toward the rail so that when pushed back down into position, the horizontal end of the wire lines up with the underside of the rail, ready for soldering. It is important that the horizontal part of the wire is parallel with the bottom of the rail to obtain the best solder joint. Adjust if necessary.
Here is one that I made but removed before soldering showing the final shape.
The dropper wire is then held in place from underneath, whilst Orange label flux is applied to the joint followed by a small amount of solder carried on the bit to the job. I know this is not the text book way of doing things, but this controls the amount of solder used better and it works. It takes me less time to do than to write about. I can understand why people choose to solder the droppers to the side of the rail, its easier, but does not look as neat.
Where this gets to be fun is with the tracks near the center of 2 foot or wider baseboards as there are invariably baseboard members in the way and one starts to run out of reach. Occasionally I have shifted where I put the droppers for easier access underneath.
Tag strips are then fitted in place usually under the rail ends of adjacent track panels. The end track panels have two sets of droppers fixed at the inner end, as seen to the right of the tag strips. This reduces the amount of cable needed to wire things up. The inner track panels have one set at each end.
The dropper wires are then fiddled through the tags, but not soldered at this stage. Any poorly soldered joints usually make their presence known at this stage.
Dropper wires.
The method I use dates back to my involvement with the North London Group's layout Heckmondwike and has been successfully used on Bodmin and my layout Green Street. The golden rule is a minimum of two dropper wires per length of rail or rail section (crossing or switch). This is to build in some redundancy and increase reliability. If one joint fails, and they do, things will continue to work. Only when both fail do things stop and then there will be two joints to mend, but less often.
I use 22 swg tinned copper wire for preference. A batch of wires are cut to length (never enough) and the end 2.5 - 3mm bent at right angles to the rest.
Holes are drilled through the base board next to the outside of the rail, being careful not to mark the head of the rail. A small piece of scrap plastic drilled through and placed against the chuck can serve this purpose. My drill features a hexagon quick release system (sometimes known as Snappy) and I have some drills with quite a smooth face to the holding piece. I previously used a 1mm drill for this job, but as the smallest drill in the set was 1.5mm, I have used that instead and has the advantage of being longer.
After inserting the dropper wires into the holes, the end of the wire is pulled up and the last 5mm or so of the vertical part is gently bent inward toward the rail so that when pushed back down into position, the horizontal end of the wire lines up with the underside of the rail, ready for soldering. It is important that the horizontal part of the wire is parallel with the bottom of the rail to obtain the best solder joint. Adjust if necessary.
Here is one that I made but removed before soldering showing the final shape.
The dropper wire is then held in place from underneath, whilst Orange label flux is applied to the joint followed by a small amount of solder carried on the bit to the job. I know this is not the text book way of doing things, but this controls the amount of solder used better and it works. It takes me less time to do than to write about. I can understand why people choose to solder the droppers to the side of the rail, its easier, but does not look as neat.
Where this gets to be fun is with the tracks near the center of 2 foot or wider baseboards as there are invariably baseboard members in the way and one starts to run out of reach. Occasionally I have shifted where I put the droppers for easier access underneath.
Tag strips are then fitted in place usually under the rail ends of adjacent track panels. The end track panels have two sets of droppers fixed at the inner end, as seen to the right of the tag strips. This reduces the amount of cable needed to wire things up. The inner track panels have one set at each end.
The dropper wires are then fiddled through the tags, but not soldered at this stage. Any poorly soldered joints usually make their presence known at this stage.
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Last edited by Tony Wilkins on Tue Mar 31, 2020 9:26 pm, edited 1 time in total.
Inspiration from the past. Dreams for the future.
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Tony Wilkins
- Posts: 818
- Joined: Tue Mar 20, 2012 3:57 pm
Re: Brimsdown-The last grand project.
The above could be subtitled. How much can one write about a piece of bent wire?
Mundane topic number two: Tag strips.
The ones I use come in strips of 30 holes with 28 tags fitted.
With one notable exception, these need to be cut down for use. In this example for ten ways.
I use more two way tags than anything else and I used to laboriously cut between the tags with a razor saw. But with the quantity I need for this project, life's too short.
With the design of these tags strips, it is possible to remove individual tags by squeezing the retaining tabs inward and I then move the first one to the end hole and then remove every other one.
Next cut the paxolin at every other hole. A chunky pair of cutters is best for this, but hold on to both halves while you do this.
Next the excess bits are trimmed off
and then cleaned up with a file.
To increase the tag retention, I bend the tabs out at the back of the strip with pliers.
Something else I do depending on need, is to bend the tags up to make inserting wires easier when in place under the baseboard.
The cables and tag strips are now fitted to the point motors
and pin one marked.
X and Y are the crossings of the tandem turnout above. X has three droppers and Y four.
I should also point out that consideration needs to be given to section breaks as this may well affect the tag arrangement.
The notable exception mentioned earlier was for the jumper connection cables between the baseboards. For these I generally need at least 38 ways, which requires one 28 way tag strip and of course a 10 way one. Depending on the baseboard space available they could be mounted separately or together as here.
These are only temporarily fitted in place at present so I can mark the numbers of the tags. They will need to be removed later for wiring to the connectors.
The next job is connecting all the common returns together with bare copper wire. Again nothing is soldered yet.
Mundane topic number two: Tag strips.
The ones I use come in strips of 30 holes with 28 tags fitted.
With one notable exception, these need to be cut down for use. In this example for ten ways.
I use more two way tags than anything else and I used to laboriously cut between the tags with a razor saw. But with the quantity I need for this project, life's too short.
With the design of these tags strips, it is possible to remove individual tags by squeezing the retaining tabs inward and I then move the first one to the end hole and then remove every other one.
Next cut the paxolin at every other hole. A chunky pair of cutters is best for this, but hold on to both halves while you do this.
Next the excess bits are trimmed off
and then cleaned up with a file.
To increase the tag retention, I bend the tabs out at the back of the strip with pliers.
Something else I do depending on need, is to bend the tags up to make inserting wires easier when in place under the baseboard.
The cables and tag strips are now fitted to the point motors
and pin one marked.
X and Y are the crossings of the tandem turnout above. X has three droppers and Y four.
I should also point out that consideration needs to be given to section breaks as this may well affect the tag arrangement.
The notable exception mentioned earlier was for the jumper connection cables between the baseboards. For these I generally need at least 38 ways, which requires one 28 way tag strip and of course a 10 way one. Depending on the baseboard space available they could be mounted separately or together as here.
These are only temporarily fitted in place at present so I can mark the numbers of the tags. They will need to be removed later for wiring to the connectors.
The next job is connecting all the common returns together with bare copper wire. Again nothing is soldered yet.
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Inspiration from the past. Dreams for the future.
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Tony Wilkins
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Re: Brimsdown-The last grand project.
Having wired up the main part of the common return for the track and point motors, the supply rails are connected up with insulated wire, each track having its own dedicated colour. At this stage it may be found desirable to begin soldering some of the joints to prevent wires falling out of their tags.
What one needs to watch out for is that you don't solder tags where additional wires are likely to be added later, for instance with the point motor tag strips where the common return is needed for both the point motor return and one side of the common crossing switch. The thin black wire here.
I guess this brings us onto mundane topic number 3 wire / cable.
There are three main types of cable, solid core or single strand, multi strand and multi way or multi core.
Single strand as its name implies has a single conducting wire. This is useful for fixed wiring installations as it tends to stay put once formed, but does not take kindly to repeated flexing and will soon fracture causing an open circuit or worse an intermittent connection.
Multi strand cable has more than one strand of wire in its core, typically 7, 16 or more. This should be used for flexible applications such as jumper cables where movement is expected.
It is even possible to get extra flexible cable, which is typically used for applications such as meter and test probes as they are subjected to more flexing than most.
Multi core cable has multiple conductors individually insulated usually within an outer cover, each conductor may be either single or multi strand.
There is of course much more to it than this. Cables have both a voltage and current rating and it is important to choose the correct rating for the job in hand, so let us expand a little on this.
Ignoring mains cables for now and concentrating on our typical low voltage application 12 - 16 volts. It is highly unlikely the voltage rating of any cable will be an issue for our purposes, which means that the main concerns will be current carrying capacity and voltage drop due to resistance and I shall try to avoid this getting too technical.
Cable is specified by the number of strands and the diameter of those stands and increasingly these days the cross sectional area. The current rating varies accordingly.
Typical single core cable is specified as (1/0.6) meaning one strand of wire 0.6mm diameter. This is rated at 1.5 Amps.
The wire I am using to wire up the track within each baseboard is a mix of (1/0.9mm dia) and 1mm square lighting cable, which is rated up to 15 Amps.
By contrast telephone cable (the thin black cable in the above picture) is only rated at 0.25 Amp.
Multi strand cable is specified typically as follows
(7/0.2) seven strands of wire 0.2mm dia. Rated 1.4 Amps.
(16/0.2) sixteen strands of wire 0.2mm dia. Rated 3 Amps.
(24/0.2) Rated 6 Amps.
(32/0.2) Rated 10 Amps.
(30/0.25) Rated 25 Amps.
It should be born in mind that the current rating is for a continuous current with the cable in free air to avoid overheating. If it is enclosed then it will need to be de-rated. This particularly applies to multi core cables where multiple conductors are generating heat at the same time.
This begs the question whether DCC layouts should be wired with (24/0.2) cable in view of the current supply available. However under short circuit conditions DCC power supplies shut down very rapidly so for most small layouts (16/0.2) cable should suffice.
For larger layouts, such as mine, voltage drop over long lengths of cable is the enemy, hence the requirement for heavier cable for the traction and auxiliary supply cables.
It may be thought that cable does not have much resistance, over a longer length it can be significant. Take a 100 meter reel, find the two ends and measure the resistance. For thinner wires it can be several ohms. Then consider that each circuit has two wires, a feed and a return, which will be in series so doubling the total resistance.
I learned this lesson the hard way many years ago. Mike Sergent, who was Heckmondwike's electrical gaffer asked if anybody in the group had any wire he could use to begin wiring up the layout. I had a large reel of red (7/007) cable (the 007 being thousandths of a inch) the equivalent to (7/02), which I lent him to be able to make a start. About a month later Mike asked me if I had any more wire. When I inquired what he had done with the wire I already gave him, he informed me that he had used it all. All 500 yards of it! I thought no more about it other than the fact that most of the layout wiring would all be the same colour, until the first time we came to run trains around the layout. Trains appeared slowly from the fiddle yard, gradually gaining speed as they approached what was to become the middle of the scenic part of the layout only to begin slowing again as they approached the the other end of the layout. A quick check with a meter revealed that the 12 volts applied to the track near the power supply reduced to something nearer 8 volts at the opposite side of the layout. This was entirely down to the resistance in the wiring circuit and the current the loco was attempting to draw from the track.
Ohms law states that for a given voltage, the current flow is inversely proportionate to the resistance, so as the resistance increases, the current falls and with it the available power at the far end.
Considering that typical motors back then could draw anything up to an amp, at that current 1 ohm of resistance would lose 1 volt of the available supply.
Modern motors being so much more efficient, this effect is far less of a problem, but I still have many locos powered by iron age current hungry motors.
The solution of course is thicker cable.
Regards
Tony.
What one needs to watch out for is that you don't solder tags where additional wires are likely to be added later, for instance with the point motor tag strips where the common return is needed for both the point motor return and one side of the common crossing switch. The thin black wire here.
I guess this brings us onto mundane topic number 3 wire / cable.
There are three main types of cable, solid core or single strand, multi strand and multi way or multi core.
Single strand as its name implies has a single conducting wire. This is useful for fixed wiring installations as it tends to stay put once formed, but does not take kindly to repeated flexing and will soon fracture causing an open circuit or worse an intermittent connection.
Multi strand cable has more than one strand of wire in its core, typically 7, 16 or more. This should be used for flexible applications such as jumper cables where movement is expected.
It is even possible to get extra flexible cable, which is typically used for applications such as meter and test probes as they are subjected to more flexing than most.
Multi core cable has multiple conductors individually insulated usually within an outer cover, each conductor may be either single or multi strand.
There is of course much more to it than this. Cables have both a voltage and current rating and it is important to choose the correct rating for the job in hand, so let us expand a little on this.
Ignoring mains cables for now and concentrating on our typical low voltage application 12 - 16 volts. It is highly unlikely the voltage rating of any cable will be an issue for our purposes, which means that the main concerns will be current carrying capacity and voltage drop due to resistance and I shall try to avoid this getting too technical.
Cable is specified by the number of strands and the diameter of those stands and increasingly these days the cross sectional area. The current rating varies accordingly.
Typical single core cable is specified as (1/0.6) meaning one strand of wire 0.6mm diameter. This is rated at 1.5 Amps.
The wire I am using to wire up the track within each baseboard is a mix of (1/0.9mm dia) and 1mm square lighting cable, which is rated up to 15 Amps.
By contrast telephone cable (the thin black cable in the above picture) is only rated at 0.25 Amp.
Multi strand cable is specified typically as follows
(7/0.2) seven strands of wire 0.2mm dia. Rated 1.4 Amps.
(16/0.2) sixteen strands of wire 0.2mm dia. Rated 3 Amps.
(24/0.2) Rated 6 Amps.
(32/0.2) Rated 10 Amps.
(30/0.25) Rated 25 Amps.
It should be born in mind that the current rating is for a continuous current with the cable in free air to avoid overheating. If it is enclosed then it will need to be de-rated. This particularly applies to multi core cables where multiple conductors are generating heat at the same time.
This begs the question whether DCC layouts should be wired with (24/0.2) cable in view of the current supply available. However under short circuit conditions DCC power supplies shut down very rapidly so for most small layouts (16/0.2) cable should suffice.
For larger layouts, such as mine, voltage drop over long lengths of cable is the enemy, hence the requirement for heavier cable for the traction and auxiliary supply cables.
It may be thought that cable does not have much resistance, over a longer length it can be significant. Take a 100 meter reel, find the two ends and measure the resistance. For thinner wires it can be several ohms. Then consider that each circuit has two wires, a feed and a return, which will be in series so doubling the total resistance.
I learned this lesson the hard way many years ago. Mike Sergent, who was Heckmondwike's electrical gaffer asked if anybody in the group had any wire he could use to begin wiring up the layout. I had a large reel of red (7/007) cable (the 007 being thousandths of a inch) the equivalent to (7/02), which I lent him to be able to make a start. About a month later Mike asked me if I had any more wire. When I inquired what he had done with the wire I already gave him, he informed me that he had used it all. All 500 yards of it! I thought no more about it other than the fact that most of the layout wiring would all be the same colour, until the first time we came to run trains around the layout. Trains appeared slowly from the fiddle yard, gradually gaining speed as they approached what was to become the middle of the scenic part of the layout only to begin slowing again as they approached the the other end of the layout. A quick check with a meter revealed that the 12 volts applied to the track near the power supply reduced to something nearer 8 volts at the opposite side of the layout. This was entirely down to the resistance in the wiring circuit and the current the loco was attempting to draw from the track.
Ohms law states that for a given voltage, the current flow is inversely proportionate to the resistance, so as the resistance increases, the current falls and with it the available power at the far end.
Considering that typical motors back then could draw anything up to an amp, at that current 1 ohm of resistance would lose 1 volt of the available supply.
Modern motors being so much more efficient, this effect is far less of a problem, but I still have many locos powered by iron age current hungry motors.
The solution of course is thicker cable.
Regards
Tony.
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Inspiration from the past. Dreams for the future.
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Tony Wilkins
- Posts: 818
- Joined: Tue Mar 20, 2012 3:57 pm
Re: Brimsdown-The last grand project.
The previous post has just been edited and extended since first submitted.
I must admit that I hadn't intended this to turn into a treaties on wiring, but anyway here goes.
As well as cable to wire up each baseboard, we need connectors in between them. There are two main ways to connect up a layout, star and daisy chain formation. With Star formations each baseboard has a loom or jumper cable connecting it to a central point, usually the control panel. Daisy chain formations have each baseboard connected to its neighbour and are by far the most common. Both schemes have their pros and cons.
Star formations use fewer total connections as each connection goes only to the baseboard it controls and allows each baseboard to be tested in isolation. Against this generally more of the wires within each loom will need to be thicker to carry traction currents and they will get progressively longer to reach the more distant baseboards. Therefore this system tends to better suit smaller layouts although the irony is that in many ways it would be better suited to larger layouts, but the growing collection of cable looms reminiscent of the underground is a definite deterrent.
Daisy chain formations use more interconnections as there will be jumpers between each baseboard interface, however they will generally be shorter in consequence. Some cable runs will span multiple baseboards and hence contain multiple connection joints. This is potentially their weak point as with cheap connectors failures of any joint will cause problems. Yet this system tends to be that preferred to wire up most layouts mine included.
It therefore follows that reliable connectors are a must. 40 years ago the choice of connector types was much wider than it is today. Basically if it is not used somewhere in the computer or automotive industry it seems to have become obsolete.
D types are favoured by many modelers as they are readily obtainable and reasonably priced. However a word of caution. There are two types. The cheaper ones have pins formed from a rolled strip and the line where the two edges of the strip meet is visible when viewed from the front. The better type have turned pins meaning they are machine turned and then gold plated. This type of connector has a rated life of so many insertions. For the rolled pins I have seen some types quoted for as low as 25 insertions, although 100 is more typical. This explains why they can fail so suddenly. The turned pin ones can be in the thousands.
The type of multi-way connector I use I came across quite by accident when helping to empty a cupboard when I worked for BT back in the 1980s. My governor was glad to see the back of them as they had been there for some while. The building needed to be emptied before we moved to the main factory site at Brimsdown, It was subsequently replace by a Sainsbury's.
Here is one of the same type in situ.
More anon.
I must admit that I hadn't intended this to turn into a treaties on wiring, but anyway here goes.
As well as cable to wire up each baseboard, we need connectors in between them. There are two main ways to connect up a layout, star and daisy chain formation. With Star formations each baseboard has a loom or jumper cable connecting it to a central point, usually the control panel. Daisy chain formations have each baseboard connected to its neighbour and are by far the most common. Both schemes have their pros and cons.
Star formations use fewer total connections as each connection goes only to the baseboard it controls and allows each baseboard to be tested in isolation. Against this generally more of the wires within each loom will need to be thicker to carry traction currents and they will get progressively longer to reach the more distant baseboards. Therefore this system tends to better suit smaller layouts although the irony is that in many ways it would be better suited to larger layouts, but the growing collection of cable looms reminiscent of the underground is a definite deterrent.
Daisy chain formations use more interconnections as there will be jumpers between each baseboard interface, however they will generally be shorter in consequence. Some cable runs will span multiple baseboards and hence contain multiple connection joints. This is potentially their weak point as with cheap connectors failures of any joint will cause problems. Yet this system tends to be that preferred to wire up most layouts mine included.
It therefore follows that reliable connectors are a must. 40 years ago the choice of connector types was much wider than it is today. Basically if it is not used somewhere in the computer or automotive industry it seems to have become obsolete.
D types are favoured by many modelers as they are readily obtainable and reasonably priced. However a word of caution. There are two types. The cheaper ones have pins formed from a rolled strip and the line where the two edges of the strip meet is visible when viewed from the front. The better type have turned pins meaning they are machine turned and then gold plated. This type of connector has a rated life of so many insertions. For the rolled pins I have seen some types quoted for as low as 25 insertions, although 100 is more typical. This explains why they can fail so suddenly. The turned pin ones can be in the thousands.
The type of multi-way connector I use I came across quite by accident when helping to empty a cupboard when I worked for BT back in the 1980s. My governor was glad to see the back of them as they had been there for some while. The building needed to be emptied before we moved to the main factory site at Brimsdown, It was subsequently replace by a Sainsbury's.
Here is one of the same type in situ.
More anon.
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Inspiration from the past. Dreams for the future.
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Andrew Bluett-Duncan
- Posts: 84
- Joined: Tue Mar 01, 2016 7:47 pm
Re: Brimsdown-The last grand project.
Hello Tony
A clear explanation of wiring requirements for both DC and DCC. I could have done with this a few months back when I was installing the main traction current feeds for Yeovil. I ended up using 32/02 just to be on the safe side and in fact twisted them together which I’m reliably informed reduces interference, significant if using servos. Would your words and picture be worth replicating in the society magazine do you think? And in fact not just for this aspect but your general approach to wiring?
Edit: l posted the above not realising that you added to the topic two posts ago and then added in a new post late last night.
Diaisy or Star? Daisy I understand and would be ok on a very small layouts as you say. Star I didn’t completely follow unless it’s the way I ve wired Yeovil Pen Mill?
That is:
1. Traction bus(One for each district) ,
2. a Servo bus,
3. an Odds & Sods bus
4. and a DCC Control bus.
Each baseboard is fed directly off each bus with the exception of the ZTC control bus which is there to provide plug in points for the handhelds.
Could you run to a diagram or two to further illustrate the principles ?
Kind regards
Andrew
A clear explanation of wiring requirements for both DC and DCC. I could have done with this a few months back when I was installing the main traction current feeds for Yeovil. I ended up using 32/02 just to be on the safe side and in fact twisted them together which I’m reliably informed reduces interference, significant if using servos. Would your words and picture be worth replicating in the society magazine do you think? And in fact not just for this aspect but your general approach to wiring?
Edit: l posted the above not realising that you added to the topic two posts ago and then added in a new post late last night.
Diaisy or Star? Daisy I understand and would be ok on a very small layouts as you say. Star I didn’t completely follow unless it’s the way I ve wired Yeovil Pen Mill?
That is:
1. Traction bus(One for each district) ,
2. a Servo bus,
3. an Odds & Sods bus
4. and a DCC Control bus.
Each baseboard is fed directly off each bus with the exception of the ZTC control bus which is there to provide plug in points for the handhelds.
Could you run to a diagram or two to further illustrate the principles ?
Kind regards
Andrew
My Layout : Yeovil Pen Mill 1922. http://85a.co.uk/forum/view_topic.php?i ... d=6&page=1
and on the new Templot Forum https://85a.uk/templot/club/index.php?t ... -in-em.11/
and on the new Templot Forum https://85a.uk/templot/club/index.php?t ... -in-em.11/
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Tony Wilkins
- Posts: 818
- Joined: Tue Mar 20, 2012 3:57 pm
Re: Brimsdown-The last grand project.
Hi Andrew.
32/02 is fine for what you are doing. What you have created by twisting the supply and return wires is know as a twisted pair. The theory being that two wires in close proximity carrying equal but opposite currents generate equal and opposite magnetic fields which therefore cancel each other out. By the same token any magnetic spikes will generate an equal voltage pulse in each conductor so again net result, nil. It is a cheaper alternative to earthed screening.
I guess to some extent this depends on Editor Tim and how short of copy he is, but although I obviously have the original pictures, the only copy of the text is on here.
Diagram as requested.
It is also possible to combine elements of both systems for instance Daisy chaining the power bus combined with a Star arrangement for the control cables.
The cables shown in the picture with the connector are the main power bus for my layout, which will form a ring running around the entire layout, however these connectors will also carry the control lines as well.
Regards
Tony.
Andrew Bluett-Duncan wrote:Hello Tony
A clear explanation of wiring requirements for both DC and DCC. I could have done with this a few months back when I was installing the main traction current feeds for Yeovil. I ended up using 32/02 just to be on the safe side and in fact twisted them together which I’m reliably informed reduces interference, significant if using servos.
32/02 is fine for what you are doing. What you have created by twisting the supply and return wires is know as a twisted pair. The theory being that two wires in close proximity carrying equal but opposite currents generate equal and opposite magnetic fields which therefore cancel each other out. By the same token any magnetic spikes will generate an equal voltage pulse in each conductor so again net result, nil. It is a cheaper alternative to earthed screening.
Would your words and picture be worth replicating in the society magazine do you think? And in fact not just for this aspect but your general approach to wiring?
I guess to some extent this depends on Editor Tim and how short of copy he is, but although I obviously have the original pictures, the only copy of the text is on here.
Daisy chain or Star? Daisy chain I understand and would be ok on a very small layouts as you say. Star I didn’t completely follow unless it’s the way I've wired Yeovil Pen Mill?
That is:
1. Traction bus(One for each district) ,
2. a Servo bus,
3. an Odds & Sods bus
4. and a DCC Control bus.
Each baseboard is fed directly off each bus with the exception of the ZTC control bus which is there to provide plug in points for the handhelds.
Could you run to a diagram or two to further illustrate the principles ?
Kind regards
Andrew
Diagram as requested.
It is also possible to combine elements of both systems for instance Daisy chaining the power bus combined with a Star arrangement for the control cables.
The cables shown in the picture with the connector are the main power bus for my layout, which will form a ring running around the entire layout, however these connectors will also carry the control lines as well.
Regards
Tony.
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Andrew Bluett-Duncan
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Re: Brimsdown-The last grand project.
Hello Tony
Well you don't hang around do you. Thanks for the explanation of why I twisted the wires together. Rather unintelligently I just read about it on the Merg site (Davy Dicks treatise on layout wiring) and carried out his ideas without really understanding why! So now I'm a further forward in my understanding, so thank you.
As to the article, if Tim doesnt have space then I'd be pretty sure Steve Young over on the EM gauge society would probably. And maybe a bit of a wild guess that a lot of Scalefour Society are also members of EM Society, so a lot of the appropriate audience would benefit.
And yes the Star approach is the way I've wired Yeovil P.M. which as soon as I saw your second diagram became clear. Sorry its not your words that were inadequate, I'm a predominately visual person and often get confused when reading anything complicated. When I built my first Finney kit I think i read the sparsely illustrated, but otherwise highly comprehensive instructions, about 5 times before I got the hang of it!
Thanks again
Kind regards
Andrew
Well you don't hang around do you. Thanks for the explanation of why I twisted the wires together. Rather unintelligently I just read about it on the Merg site (Davy Dicks treatise on layout wiring) and carried out his ideas without really understanding why! So now I'm a further forward in my understanding, so thank you.
As to the article, if Tim doesnt have space then I'd be pretty sure Steve Young over on the EM gauge society would probably. And maybe a bit of a wild guess that a lot of Scalefour Society are also members of EM Society, so a lot of the appropriate audience would benefit.
And yes the Star approach is the way I've wired Yeovil P.M. which as soon as I saw your second diagram became clear. Sorry its not your words that were inadequate, I'm a predominately visual person and often get confused when reading anything complicated. When I built my first Finney kit I think i read the sparsely illustrated, but otherwise highly comprehensive instructions, about 5 times before I got the hang of it!
Thanks again
Kind regards
Andrew
My Layout : Yeovil Pen Mill 1922. http://85a.co.uk/forum/view_topic.php?i ... d=6&page=1
and on the new Templot Forum https://85a.uk/templot/club/index.php?t ... -in-em.11/
and on the new Templot Forum https://85a.uk/templot/club/index.php?t ... -in-em.11/
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Will L
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Re: Brimsdown-The last grand project.
Andrew Bluett-Duncan wrote:... if Tim doesn't have space ..
Don't think that's likely
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Tony Wilkins
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Re: Brimsdown-The last grand project.
So some more detail about what are now my standard connector system.
When I first came across these they were marketed as Varelco 8016 series video connectors.
They were apparently designed in Canada for the video industry. No I couldn't work it out either.
Over the years this has changed to Elco, which is still moulded into the plastic, but are currently known as Edac 516 series racking connectors.
There are several features about them that I like. It may be noted from the above pictures that they do not have the contacts ready mounted. This has the advantage that the soldering can be done away from the plastic body, so no risk of heat damage, except perhaps to fingers, and the contacts inserted afterwards. The contacts are available in a range of styles. Solder tag, which I prefer. Crimp, for those who don't like soldering, but needs the corresponding crimping tool, and wire wrap versions, another solderless system.
Below is a solder tag version together with a length of 32/02 cable ready striped.
The forked end mates with an identical tag at 90 degrees, like so.
Unlike most contact designs, which have 1 or 2 mating surfaces, these are designed to meet on the corners of the slots thus creating 4 mating surfaces simultaneously. The wiping action ensures good contact. Each contact is rated to carry 8.5 amps maximum, but with a very low contact resistance, 6 Milli-ohms max, are equally good with low current signal wires as well.
To wire up a contact, the wire is inserted through the hole in the tag end, making sure all the strands are through and folded back over
then soldered. It is important to maintain a straight alignment.
With bare wires in close proximity sleeving is essential.
Sleeving tool and sleeving oil required.
Only the slightest smear of sleeving oil is required to get the rubber sleeve onto the tines of the sleeving tool or it will end up getting everywhere.
This is gently stretched to get it over the contact
and the sleeve slid off the tines into place.
The contact can then be inserted into the connector until it clicks home.
One advantage of this design is that only the desired number of contacts need be inserted as you go.
It is though prudent to allow a few extra, otherwise inevitably one will need more later.
The connector shown has a capacity of 38 ways.
They are available in 20, 38, 56, 90 and 120 way versions. The 120 way ones are a really chunky connector. I used one under Green Street between two baseboards. Accessories include extractor and insertion tools. The insertion tool is useful when trying to insert a contact on the end of a thin cable.
One other feature of these connectors is that they are self jacking. The hole in the center of the socket has a threaded bush that mates with a screw thread on the plug so that the two halves screw together or apart rather than being pushed or pulled.
When I first came across these they were marketed as Varelco 8016 series video connectors.
They were apparently designed in Canada for the video industry. No I couldn't work it out either.
Over the years this has changed to Elco, which is still moulded into the plastic, but are currently known as Edac 516 series racking connectors.
There are several features about them that I like. It may be noted from the above pictures that they do not have the contacts ready mounted. This has the advantage that the soldering can be done away from the plastic body, so no risk of heat damage, except perhaps to fingers, and the contacts inserted afterwards. The contacts are available in a range of styles. Solder tag, which I prefer. Crimp, for those who don't like soldering, but needs the corresponding crimping tool, and wire wrap versions, another solderless system.
Below is a solder tag version together with a length of 32/02 cable ready striped.
The forked end mates with an identical tag at 90 degrees, like so.
Unlike most contact designs, which have 1 or 2 mating surfaces, these are designed to meet on the corners of the slots thus creating 4 mating surfaces simultaneously. The wiping action ensures good contact. Each contact is rated to carry 8.5 amps maximum, but with a very low contact resistance, 6 Milli-ohms max, are equally good with low current signal wires as well.
To wire up a contact, the wire is inserted through the hole in the tag end, making sure all the strands are through and folded back over
then soldered. It is important to maintain a straight alignment.
With bare wires in close proximity sleeving is essential.
Sleeving tool and sleeving oil required.
Only the slightest smear of sleeving oil is required to get the rubber sleeve onto the tines of the sleeving tool or it will end up getting everywhere.
This is gently stretched to get it over the contact
and the sleeve slid off the tines into place.
The contact can then be inserted into the connector until it clicks home.
One advantage of this design is that only the desired number of contacts need be inserted as you go.
It is though prudent to allow a few extra, otherwise inevitably one will need more later.
The connector shown has a capacity of 38 ways.
They are available in 20, 38, 56, 90 and 120 way versions. The 120 way ones are a really chunky connector. I used one under Green Street between two baseboards. Accessories include extractor and insertion tools. The insertion tool is useful when trying to insert a contact on the end of a thin cable.
One other feature of these connectors is that they are self jacking. The hole in the center of the socket has a threaded bush that mates with a screw thread on the plug so that the two halves screw together or apart rather than being pushed or pulled.
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Terry Bendall
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Re: Brimsdown-The last grand project.
The video multi way connectors look very useful. So far I have relied on my stock of secondhand multiway connectors of various vintages although finding them is now not very easy. I use 16/02 cable for traction current and I prefer a larger connector than the standard D type connector which is of course easily available.
I guess Tony that the sleeving that you use avoids the problems of heat shrink sleeving which I tend to use?
Terry Bendall
I guess Tony that the sleeving that you use avoids the problems of heat shrink sleeving which I tend to use?
Terry Bendall
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Paul Townsend
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Re: Brimsdown-The last grand project.
See my advert in classified section for these connectors......edited 6/5/20 .....now all gone to 2 of us.
I previously mentioned cables available and got smacked for thread drift! Fair enough
I previously mentioned cables available and got smacked for thread drift! Fair enough
Last edited by Paul Townsend on Wed May 06, 2020 6:22 am, edited 1 time in total.
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grovenor-2685
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Re: Brimsdown-The last grand project.
Terry Bendall wrote:I guess Tony that the sleeving that you use avoids the problems of heat shrink sleeving which I tend to use?
Terry Bendall
What are the problems with heat shrink?
I would use it for this sort of application, no need for special tools, the soldering iron will shrink is as soon as you have completed the joint.
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Rod Cameron
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Re: Brimsdown-The last grand project.
Interesting stuff on wiring Tony, thank you. On Balcombe, which is daisy-chained throughout, to minimise voltage drop I used buses of copper hi-fi speaker cable running directly between the interboard connectors, as well as the 'slow line' cables feeding the droppers on each board. The connectors are currently mains-rated choc blocks, which are robust but you do have to watch for the screw terminals coming loose.
Measuring DCC track voltage it is constant all the way round.
Measuring DCC track voltage it is constant all the way round.
Rod
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John Palmer
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Re: Brimsdown-The last grand project.
Thank you, Tony, for a really useful set of posts about wiring matters generally and the Edac connector system in particular. The scales have now fallen from my eyes as to how these work.
For our Burnham layout, begun in the 1970's, we adopted for our board connectors the Belling Lee Unitor range of connector chassis, backshells and inserts. These were a popular military grade connector and have given us absolutely trouble-free service. I see that they are still available (just about) so may acquire a set for a new, demountable switch/ground frame panel I am constructing for the layout. However, if I hit problems sourcing the required components I may now go the Edac route rather than use the readily available D-sub connectors I have to hand. I do like the self-jacking feature of the Edac system with the jack screw in the centre of the connector, just where it is needed to even the mating/parting forces.
It's certainly true that you can use a soldering iron to reduce heat shrink tubing to the required size, but I always seem to end up depositing some solder or muck on the heat shrink. I prefer the approach of our resident electronics guru Gordon Dyte, who uses a nifty little hot air gun designed for this purpose. I haven't tried it but suspect that a hair drier would be equally effective.
For our Burnham layout, begun in the 1970's, we adopted for our board connectors the Belling Lee Unitor range of connector chassis, backshells and inserts. These were a popular military grade connector and have given us absolutely trouble-free service. I see that they are still available (just about) so may acquire a set for a new, demountable switch/ground frame panel I am constructing for the layout. However, if I hit problems sourcing the required components I may now go the Edac route rather than use the readily available D-sub connectors I have to hand. I do like the self-jacking feature of the Edac system with the jack screw in the centre of the connector, just where it is needed to even the mating/parting forces.
It's certainly true that you can use a soldering iron to reduce heat shrink tubing to the required size, but I always seem to end up depositing some solder or muck on the heat shrink. I prefer the approach of our resident electronics guru Gordon Dyte, who uses a nifty little hot air gun designed for this purpose. I haven't tried it but suspect that a hair drier would be equally effective.
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Terry Bendall
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Re: Brimsdown-The last grand project.
John Palmer wrote:I prefer the approach of our resident electronics guru Gordon Dyte, who uses a nifty little hot air gun designed for this purpose. I haven't tried it but suspect that a hair drier would be equally effective.
I use a paint stripper heat gun on the lowest heat setting and with a nozzel to confine/direct the heat and that works well but I have seen a hair dryer used.
Terry Bendall
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triumph3
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Re: Brimsdown-The last grand project.
This is an excellent series, can I suggest that this is incorporated into the Scalefour Society Manual?
David
David
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Tony Wilkins
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Re: Brimsdown-The last grand project.
Paul Townsend wrote:See my advert in classified section for these connectors.
I previously mentioned cables available and got smacked for thread drift! Fair enough
Only lightly
Inspiration from the past. Dreams for the future.
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Tony Wilkins
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Re: Brimsdown-The last grand project.
I am not going to reply individually to all the above comments for perhaps obvious reasons, but generally, a hot air gun of some sort is the recommended way to shrink heat shrink sleeving although, like most, I have resorted to a soldering iron to do the job.
There is a good reason why I use rubber sleeves rather than heat shrink.
It is the traditional way of doing it. Besides, I have very little heat shrink sleeving.
The tray on the left has H20 sleeving and that on the right H12.
Translation: H20 has a 2.0 mm bore and H12 by the same logic a 1.2 mm bore. As always they come in a range of sizes.
Whilst I use the proper tool to apply the sleeving, due to the number of edges these contacts have to snag the sleeve, they are not mandatory and for many applications are not really needed. For wiring something like a D type connector, it is easier to slip the sleeving over the wire before stripping the end and definitely before soldering or it is too late; and don't forget the cover either.
When starting to cover this particular subtopic, I was very much in two minds as to whether to include the wiring and associated paraphernalia here or begin a new thread under the electrics subheading rather than have it buried in the middle of the main tread. As the object of the exercise was to keep things together in one place, there seemed little point.
Tony.
There is a good reason why I use rubber sleeves rather than heat shrink.
It is the traditional way of doing it. Besides, I have very little heat shrink sleeving.
The tray on the left has H20 sleeving and that on the right H12.
Translation: H20 has a 2.0 mm bore and H12 by the same logic a 1.2 mm bore. As always they come in a range of sizes.
Whilst I use the proper tool to apply the sleeving, due to the number of edges these contacts have to snag the sleeve, they are not mandatory and for many applications are not really needed. For wiring something like a D type connector, it is easier to slip the sleeving over the wire before stripping the end and definitely before soldering or it is too late; and don't forget the cover either.
When starting to cover this particular subtopic, I was very much in two minds as to whether to include the wiring and associated paraphernalia here or begin a new thread under the electrics subheading rather than have it buried in the middle of the main tread. As the object of the exercise was to keep things together in one place, there seemed little point.
Tony.
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Paul Willis
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Re: Brimsdown-The last grand project.
triumph3 wrote:This is an excellent series, can I suggest that this is incorporated into the Scalefour Society Manual?
David
David,
I'm sure that the Society would benefit from such a document.
Only one question - who is going to write it?
Cheers
Paul Willis
Deputy Chairman
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk
www.5522models.co.uk
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Tony Wilkins
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Re: Brimsdown-The last grand project.
Back to the subject in hand.
The connectors will need to be mounted somewhere. With previous layouts, I have always mounted the connectors underneath, however these present more of a challenge with age, so a different approach was called for, especially as the underside of many of these baseboards will be pretty inaccessible due to the sub-frame the straight boards rest upon. I therefore decided that the inter-board connections would be through the side face of the baseboards.
This though is to get slightly out of sequence. The first thing I needed to do was make some mounting plates for the connector.
The first ones were fashioned from some scrap Aluminium plate I had available.
Cutting the rectangular hole to just clear the base of the connector is the fun part. I resorted to using some Abra files (who remembers those?) and files to clean up the hole for a close fit. Years ago you used to be able to get rectangular Qmax cutters to do the job, but although round Qmax cutters are still available, square and rectangular ones don't seem to be. Mind you we did manage to break a couple of the bigger rectangular ones, so perhaps that's why.
The bare plate (minus connector) was used to mark a rectangle and the fixing centers on the face of the baseboard. An outer rectangle was then marked sufficient to give clearance for the plug to go through and align with the socket.
The corners of the rectangle were drilled through and the hole cut out with a coping saw.
Next the fixing holes were drilled for M3 screws and countersunk. I had some long M3 screws and these were fitted with some threaded pillars to act as standoffs for the plates. These can be seen in this picture.
The reason for these is to reduce the amount that the plug protrudes from the baseboard face.
The plugs look like this.
These have plastic covers, but metal ones are available too.
This is the one on the opposite end of the same board. The loom drops under the edge of the baseboard and is securely clamped to the inside face by a pair of large P clips.
If anybody is tempted to try these connectors remember that quality costs. However if total reliability is your quest then you won't do any better.
So here's what it is all about another two boards ready for testing. Power plugged in at the far end.
The graceful flow of track that only Templot provides.
Regards
Tony.
The connectors will need to be mounted somewhere. With previous layouts, I have always mounted the connectors underneath, however these present more of a challenge with age, so a different approach was called for, especially as the underside of many of these baseboards will be pretty inaccessible due to the sub-frame the straight boards rest upon. I therefore decided that the inter-board connections would be through the side face of the baseboards.
This though is to get slightly out of sequence. The first thing I needed to do was make some mounting plates for the connector.
The first ones were fashioned from some scrap Aluminium plate I had available.
Cutting the rectangular hole to just clear the base of the connector is the fun part. I resorted to using some Abra files (who remembers those?) and files to clean up the hole for a close fit. Years ago you used to be able to get rectangular Qmax cutters to do the job, but although round Qmax cutters are still available, square and rectangular ones don't seem to be. Mind you we did manage to break a couple of the bigger rectangular ones, so perhaps that's why.
The bare plate (minus connector) was used to mark a rectangle and the fixing centers on the face of the baseboard. An outer rectangle was then marked sufficient to give clearance for the plug to go through and align with the socket.
The corners of the rectangle were drilled through and the hole cut out with a coping saw.
Next the fixing holes were drilled for M3 screws and countersunk. I had some long M3 screws and these were fitted with some threaded pillars to act as standoffs for the plates. These can be seen in this picture.
The reason for these is to reduce the amount that the plug protrudes from the baseboard face.
The plugs look like this.
These have plastic covers, but metal ones are available too.
This is the one on the opposite end of the same board. The loom drops under the edge of the baseboard and is securely clamped to the inside face by a pair of large P clips.
If anybody is tempted to try these connectors remember that quality costs. However if total reliability is your quest then you won't do any better.
So here's what it is all about another two boards ready for testing. Power plugged in at the far end.
The graceful flow of track that only Templot provides.
Regards
Tony.
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Tony Wilkins
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Re: Brimsdown-The last grand project.
Flymo748 wrote:triumph3 wrote:This is an excellent series, can I suggest that this is incorporated into the Scalefour Society Manual?
David
David,
I'm sure that the Society would benefit from such a document.
Only one question - who is going to write it?
Cheers
Paul Willis
Deputy Chairman
I think that's known as a loaded question.
Regards
Tony.
Inspiration from the past. Dreams for the future.
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Winander
- Posts: 855
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Re: Brimsdown-The last grand project.
triumph3 wrote:This is an excellent series, can I suggest that this is incorporated into the Scalefour Society Manual?
David
Isn't this a candidate for Notes?
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