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Model Railway Express

Hints & Tips ELECTRICAL

Updated October 28th, 2010

The following Hints and Tips were contributed to Model Railway Express Magazine as a service where readers have been invited to submit "things they do" to keeps costs down, techniques they use to build their items and manage their railways in general.

These pages show the Hints and Tips categorised in the order they have been received by MRE mag. I am not promising "perfection" but as of the creation of these pages, these Hints and Tips page are also shown in order on Page 1... please click on this to access the hints in order that they have appeared in MRE Mag!

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Hints & Tips No.2 – Short out Brian Macdermott

What do you do if you are enjoying a pleasurable running session and everything suddenly shorts out?

When this happens on my layout I will almost always find it has something to do with the previous train movement. Sometimes, it’s as simple as a metal-wheeled wagon bridging an insulated rail gap on a reverse loop.

Hints & Tips No.8 – A flick of a switch Brian Macdermott

When referring to DC reverse loops, conventional wisdom says that one should drive a train into the ‘reversible section’, stop, throw the double pole/double throw (DPDT) switch, reverse the controller and then drive out.

Here is a little trick if you have a controller with switchable forward/reverse.

Drive your train into the reversible section. With the train still moving, flick the ‘backwards’ switch on your controller with one hand and - at precisely the same time - flick the DPDT switch as well. This may take a bit of getting used to, but I can now keep my trains moving with no perception of the polarity change whatsoever.

Older tender-drive locos may give a bit of a twitch, but more modern Bachmann and Hornby are easy. As far as I know, this does no harm to the motors.

Hints & Tips No.10 – Train protection Brian Macdermott

When I isolate a loco/train on my DC layout, I always turn the controller on a fraction in reverse. I occasionally find that I have accidentally isolated the wrong section. Turning the controller on for a spilt second will show up the errant train and being in reverse prevents it from running into anything ahead of it in my linear hidden sidings.

Hints & Tips No.14 – Panic Button Martin Walls, Australia

I run my power controllers through a power board that plugs into a power point fitted with an RCD safety switch (Residual Current Device).

The test button for the RCD makes a very handy ‘panic button’ for cutting track power quickly. This is useful when trains are on an intercept course at one of my many Tri-ang diamond crossings.

Hints & Tips No.81 - Diode Protection for Sidings.

By Trevor Gibbs, (Melbourne, Australia)

Model Railway and Railroad conventions dictate that a loco will run forward when the right hand running rail is Positive. We can use this to our advantage to protect locos overrunning sidings which are close to the baseboard edge and doing themselves (and our wallets) a fair bit of damage. At a discreet distance from the end of the siding, cut the rail on the LEFT hand side (as you enter the siding) and insulate it, preferably with an insulated joiner. Now bridge the gap with a 1 amp diode (a 1N4004 will do) with the bar of the diode towards the dead end of the siding.

You will be able to drive in but hopefully not too far. However reversing your loco will have it able to be driven out. There is a bit of a voltage loss of about .6 of a volt but because you are starting the loco, I doubt that you might perceive it. If your loco goes the wrong way because you misunderstood these instructions, just reverse your diode and test it.

DCC operators cannot quite do this, but it is quite prototypical that engines had to use a small rake of wagons to get another wagon parked in a siding because of light rail, insufficient clearance over the cylinders etc. Protect your siding with an “Engines must not pass this point” sign and insulate as above. Now have a Normally Open pushbutton switch with wiring bridging the insulated gap. When you are sure that your loco is set to go the correct way push your bridging button and you can drive your engine out. It is not as surefire safe as with DC operations but it will do the trick.

(A Note from Trevor - This Hint and Tip generated a few replies these are among them... not in order!)

From myself with Nick Stanbury's input

ADDITIONAL PROTECTION WHEN PROPELLING STOCK INTO A SIDING

Further to the note of Nick Stanbury, I thought of this solution and maybe it will help a few of you for straight DC anyway


Imagine if you will a long dead end siding, such as a terminal platform road. If a train is drawn in, the only protection needed is that described in the initial Hint and Tip, using a single diode to bridge a rail break an engine length or so from the buffer stop. But this will not help if a train or rake is PROPELLED into the siding and could hit the buffers before the engine is denied current. So, another diode is needed to bridge a second (outer) break (preferably in the same rail), positioned a little further from the buffer stop than the length of the longest rake you would back in.


You will also require two simple on/off switches. One switch is connected in PARALLEL with the outer diode, so that when 'on', that diode is bypassed and a train being DRAWN in can approach the end of the siding in the normal way. That engine cannot however hit the buffers as the inner diode will deny it forward current. The other switch is connected in SERIES with the inner diode, so that when switched 'off', the train engine remains isolated whilst another engine approaches the rear of the rake and draws it away.


There is still a problem with a DMU or similar train having pickups at each end and I am contemplating a solution using a photoresistor embedded in the track... watch this space...



From Paul Plowman

The idea of protecting terminal buffer stops and siding ends with a diode has been around for many years. Many modellers have used it successfully. However, there is a major shortcoming with the idea; it does not prevent over runs while propelling non-powered rolling stock such as coaches and valuable Pullman cars.

I suggest an alternative arrangement: Place an insulated joint in one rail about six inches from the buffer stops; locate all of the insulated joints in the same side rail throughout the layout; connect all of the protecting sections for each control area to the common terminal of a two-way switch; connect the two terminals of the switch to the track supply. In one position of the switch the protecting sections will have the wrong polarity and any metal wheel crossing an insulated joint will cause a dead short. The circuit breaker will then drop out and stop any further movement of trains. The operator then throws the two-way switch to clear the short circuit and the offending rolling stock can be recovered without the intervention of the hand of God. The switch is then returned to the protecting position.

The switch could be a two-way sprung push-button, which has to be held down while recovery takes place. With DC the circuit breaker would have to be of the type, which only rests after power is cut off, not one that resets automatically immediately the short circuit has been removed. The reason is because the short circuit occurs only momentarily.

I admit to not having tried this idea in practice but it should work with any item of rolling stock fitted with metal wheels and with DCC. It certainly worked with DCC yesterday when I accidentally wired up a pair of droppers the wrong way round.

From Paul Harman

Trevor Gibbs tip for DC is excellent, but DCC users should not be disillusioned as the technology to extend this technique to DCC layouts is already with us.

Users of Lenz Gold and Zimo decoders, that support asymmetric braking, have it easiest where the simple diode can be replaced with a Lenz BM1 module - which is little more than a network of five diodes that can be made easily for a few pence. It is a very simple solution that will make trains stop (with inertia) when being driven into the dead end, but allow them to be reversed out with full control of functions retained, and all the sound and lights still on.

For those DCC users that have other decoders, Brake on DC or brake signal insertion modules can be used, which is a little more complex to install, and will require a push button or similar to enable the train to be reversed out, but a useful safety stop can still be achieved.

From Graham Plowman

Trevor Gibbs raised the topic of diode protection for sidings. I have a much simpler solution: Don't design and build a layout which has track close to the edges of the boards!

Hints & Tips No.87 - Track soldering and DCC tip

By Bob Montgomery (Arkansas)

If you solder your track joints and run DCC , make sure you remove your DCC loco's from the track before soldering new joints. The static etc. generated by soldering can damage decoders. Do not ask how I found this out. Just felt that I should pass it on.


Also it may be a good idea to disconnect your DCC power supply when soldering rails, I have not fried that yet , but why take a chance.

Hints & Tips No.88 - Recycling computer parts Pt 1.

By Jeffrey Wimberly (LA, USA)

Old PC power supplies make very good power supplies for structure lighting and signalling devices. On my previous layout I used one to light over 50 structures. On my current layout the same PC power supply is pulling nearly 50 bulbs (not LEDs) and is not even starting to strain. Try that with an old train power pack.

(A Note from Trevor... There are a number of web sites which deal with making a power supply from an ATX Power supply but please use safety precautions. If you do not feel comfortable dealing with Mains power which you will have to do if your Power Supply box does not have an off switch, then get an electrician ... within your club... to help. Later feedback suggests that some form of thermal overload protection in case of a derailment is essential as Computer Power supplies are not as robust as our made to purpose ones)

Hints & Tips No.91 - Recycling computer parts Pt 2

By Thomas Statton, (Tennessee USA)

Old floppy drives and CD Roms are good sources for small motors and screws. The case should have small gauge wires and connectors for the LEDs and such. Gears and misc. parts can be gondola or open wagon junk loads when painted a rust color.

(A note from Trevor – I also used a small motor for an American 0-6-0 from a CD ROM to replace an open frame motor and a small double connector which I could not locate commercially for LEDs in the headlights of a diesel so I could remove the body totally. The motor runs very well)

Hints & Tips No.93 - Recycling computer parts Pt 3

By Thomas Statton, (Tennessee USA)

Old computer device ribbon cable looks pretty good as corrugated iron when painted a silver color. Just cut to length and glue it to your fence frame material. A little rust colour will assist the image.

Hints & Tips No.95 - Recycling computer parts Pt 4

By Kevin Smith, (Saskatchewan, Canada)

You might actually want to keep an older working computer around. You do not need a lot of speed to run things like decoder pro, make inventories of your stock using spreadsheets such as Open Office or Excel or using simple drawing packages for layout changes or simple structures. You can then keep an older computer in the layout room. And a PC with a sound card might also become the basis for a sound system on your layout.

(A Note from Trevor – You might want also to save the H&T files on an old computer just so you can refer to it and wonder why you kept an old computer under your railway - ala this hint! :). Thanks Kevin!)

Hints & Tips No.117 – Controlling maximum speed on transistor throttles.

By Trevor Gibbs (Melbourne Australia)

I use inertia transistor throttles on my layout with a minimum and maximum speed set. The maximum speed has been particularly handy when visitors come to see the layout. It is approximately set to the fastest speed I would want a loco to go and I do not have the grief of kids or adults who are kids at heart trying to run the train at slot car speeds, particularly if the adjustment is out of reach.

The modification would be easy on existing plain transistor throttles. Place a potentiometer between the throttle and the return side connecting the centre leg and the right as you look at it from the top to the right leg and the return "rail" of the throttle. Increasing this resistance decreases your maximum speed but it also means you have better control over more of a speed range for your throttle... and that is a good thing.

Hints & Tips No.125

Colour coding Wiring

by Martin Hollebone (TR Models North Hants)

When wiring your layout to operate points, lights, power feeds, etc., always use different colour multi-stranded flexible wires. Plan first with a diagram and record the colours used for each function for future reference. You will find this invaluable when checking for faults later.

Hints & Tips No.135

Running on lower voltage

by Trevor Gibbs (Melbourne Australia)


If you are still using any sort of Globe as compared to using LEDs, run your power pack at a lesser voltage than the rating quoted by about 70%. If you have 12 volt globes, try running them on say 8 volts, 6 volts should be cut down to 4 etc.


This extends your globe life remarkably and will cut down the heat factor in your train area.


Personally I run all my lights bar a few Headlights with LEDs. At 80,000 hours rated life and I am 54, I don't expect to change too many and the heat is a whole lot less. I can also run from old Mobile Phone charger transformers and get quite a few lights, well LEDs running for virtually no outlay.



Hints & Tips No.137

Using Black light or ultraviolet lights

by Rob Smith (Labrador Queensland)

Combined with fluorescent paint applied discreetly to buildings, fences and car headlights etc “Black Light or Ultra Violet lights can make an incredible effect for your village scene. Generally the ultraviolet lights are tube-type available from Electrical and Hardware stores.

There are several sizes depending on the size of display you want it on. Try mounting the light above or at the rear of your display. Or make a hill to conceal your light in your display. Caution...the effects on your display is addictive... paint stars on the backdrop, in the night sky...timed daylight to night scenes...

Hints & Tips No.139

Use of Wahl Oil

by Trevor Gibbs (Melbourne Australia)


For many years, some modellers have been using Wahl clipper oil to help with their locos maintaining good electrical contact with the track. This was dramatically shown when a friend bought an older Rivarossi Cab Forward locomotive to an exhibition which was running very raggedly. A few drops of Wahl Oil on the track and you would not have thought you were viewing the same engine!


There have been a number of spurious claims made about the product ( traction increased for example... physics tells me that oil and traction are not compatible) but the conductivity is improved if only a few drops are applied every 3-4 metres/10-12 feet or so. Like many other areas in this hobby, just do not overdo the oiling.


Hints & Tips No.142

Alternative Catenary

by Trevor Gibbs (Melbourne Australia)


You can make catenary or trolley wire for trams by stripping suitable sized copper wire and hardening it. You do this by placing one end in a vice and using a power drill, hold it reasonably tightly and start spinning the drill chuck while holding a tension.


You would think the wire would twist all over the place but it spins on itself and becomes quite rigid. Try to stop spinning before the wire actually snaps, usually just out of the drill chuck or vice. You can then make a jig to create your favourite catenary shape or length, cut the wire to length and shape and solder away.


I have also used wire in this way to make model signs for my own and club layouts, especially small signs like whistle and speed board signs for trackside details. You could use the copper wire from catenary offcuts in this way if you do not use these for the wire hangers!


Hints & Tips No.144 - Making a Turntable

by Trevor Gibbs (Melbourne Australia)

You can make a simple turntable from a length of timber (preferably plywood for dimensional stability), a reversing switch and a stereo jack, preferably one of the thicker ones at 4.8mm.

The stereo jack is wired so that the plug is on the turntable bridge side, while the socket is on (or in) your baseboard. Get it exactly in the middle of your bridge. The socket goes in your baseboard and is wired by a reversing switch to your track. The reversing switch is to get the polarity right, when your locos are rotated.

You can then sink your turntable into your baseboard or sit it on top and raise the track to it. You will need to make some sides for the turntable bridge - either a girder made from styrene or card above the rail, or a girder to cover the wooden bridge. You will also need to construct a model fence at rail height. You should now have a basic turntable to give you years of enjoyment and trouble free service.

Hints & Tips No.152

LEDs for Headlights

by Trevor Gibbs (Melbourne Australia)


I am still on DC because I like my throttles and like playing with controlling braking. Headlights are another issue as the old globes varied with the track voltage and were non directional. I have now fitted Golden White LEDs as Headlights to most of my locos. They are fairly constant with their intensity and look good.


Because you have to put a regular diode in line with the LED as well as the load resistor, if your motors are the sensitive type make a block with diodes in reverse parallel, that is Cathode to Anode at both ends and put this in series with your motor. Because Diodes drop 0.6 of a volt, your motor will need a higher starting voltage and you will hopefully be lucky enough that the loco will start just after the headlight goes on. If your Diode is sensitive, you may need two diodes in Series. But the headlight effect is worth it and they do not shine constantly in reverse!


Hints & Tips No.193

Bi Directional LEDs for Signals

by Trevor Gibbs (Melbourne Australia)


I have a number of working colour light signals home made at both ground and upper levels which I have lit by a single Bi Directional LED.


The feed in for this is a small Alternating Current and I have two switches governing each of them. The AC has one line in with two diodes in reverse direction to each other, one which will give a half wave positive feed and give a green light while the other gives a half wave negative and gives a red light. So far so good and maybe that is enough for many of you. There is very little perceptible difference between the half wave in this way and using a reversing switch.


The second switch feeds in straight from the AC to the LED, effectively shorting or bypassing the Diodes. The Feed of Red and Green together at a frequency (in Australia 50 Hz) produces a very plausible Orange-Yellow tone which does as a Caution signal. If you have room on your control panel, a three position rotary switch could also do this.


So those of you who do not want to make oscillator circuits because you feel as if you are electronic klutzes but know a little about electricity now have no excuse... so get out your soldering irons!


Hints & Tips No.196

A Source of Cable

by Trevor Gibbs (Melbourne Australia)


If your workplace is being fitted up with Network cable or Security Camera Cabling, the installers usually have long reels (by model railway standards anyway) of the cable left over. Usually it is taken for scrap and sometimes dumped.


I have increased my own supplies of this by asking for the left over cable and got various lengths which are otherwise useless to them but a treasure to us. The cable come in 4 and 6 wire, and stripped down is more than ample for most applications.


And all you have to do is ask...




Hints & Tips No.213


How To Make a Yard Floodlight – Pt 1

by Trevor Gibbs ( Melbourne Australia)


You will need about 9 inches or so of Brass Tubing 3mm should be good, a small amount of flat brass, 2 High Intensity LEDs, 2 1K resistors and some wire and 2 Bic Biro Tops (?) Intrigued? Read on


Many years ago in my teens, I bought a set of Yard Flood lights, one with four lights and the other with two. I found them again fairly recently and having a broken Light in one, thought it better to replace so I bit the bullet and opted for LEDs. They really look effective lighting up the yard, casting shadows in the right directions etc and with so little power consumption.


I really probably need at least one more and could not get another tower in reasonable condition so I have elected to make my own and one for the club ... here is how!


Drill a hole in the centre of the brass plate for the tube to fit in and solder in place. This will be the tower and the platform on which your lights will rest.



Hints & Tips No.214


How To Make a Yard Floodlight – Pt 2

by Trevor Gibbs ( Melbourne Australia)


Cut the clip part of your Bic Biro or similar top off at the end of the cap. While your top is still a half reasonable length to handle, file the rest of the clip which is moulded onto the cap so that is has a flat facet to sit on your platform.


From the end, cut the cap to about 8-10mm long. Glue some clear styrene to one end which will be where the light will be focused. Make a cap for the other end using styrene but do not glue yet. This will be the “spotlight casing”.


Wire up your LEDs with 1 wire up to 12” long. Solder the wire on the SHORTER leg of the LED. Drill a small hole in the white styrene cap and thread the wire and other leg of the LED through it then use some white glue to hold it to the back of the light


Place your selected LEDs so that the longer of the two legs (The Cathode) can be soldered to either the tube or the plate leaving a reasonable degree of movement.


At the other end of the tube solder, another length of wire with a 1K dropping resistor which will run to your power source or if it is like mine to a pair of bus wires running around the layout.


Feed your remaining two wires through the tube and join them or join them before they go through the tube. Paint to suit and you have a tower for the cost of two LEDs, some brass tube and some stuff you might have thrown out anyway!


And in something totally out of the box, here is an illustration... photos of item to follow!





NOTE – You can also make larger scale headlights from the biro caps in much the same way !

Hints & Tips No.245

Heat Sinks for Soldering Track

By Trevor Gibbs ( Melbourne Australia)

Do not risk melting plastic sleepers when soldering wire leads to the track. Use heat sinks in the form of small spring metal paper clips on each side of the solder joint.


Hints & Tips No.251


Making Elongated Meter Extensions.

By Harvey McRae (Kelowna BC, Canada)

I often get under my layout, and want to check to see if I have a broken wire. Of course the other end is away down at the other end of the layout. I made an extension cord for my Ohm/Volt/Amp Meter. This is how I got “my arms stretched” to the other end of the layout. First, find an empty wire reel. (I happened to have a spare so I did not have to take all my wire off).....Measure out the length you would like to use for the extension wires. Ideally you will have two different coloured wires. On the sides of the reel, drill two holes and buy yourself two female probe sockets that your multimeter probe leads will fit in. The female sockets should ideally be the same size as your meter probes.

Drill two holes in the ROLL part of the reel and feed your different coloured leads through these holes into and out of the centre of the roll, leaving enough length to solder to the female plugs and cover with heat shrink insulation. Bare the ends of the wire and attach to the sockets. The wire feeding through the holes in this way will act as an anchor and save unnecessary stress on your female plug solder joints when and if tension occurs. Having fed your wires through the roll of the reel, bare the other ends of the wire and solder to two alligator clips. You are now done!

Now to use the extension, clip your alligator clip to one end of your wire you want to check for continuity, plug your one side of your meter into the female plug in your roll and test with the second probe of the meter or use the second wire to reach the other far end... and measure!


Hints & Tips No.313

Cutting Tiny Wires using a Razor Saw

By James Fulham

Put the wire on a surface like a cutting mat. Put the saw blade across the wire so that it it trapped between two of the teeth. Now gently pull the wire to remove the insulation.

Depending upon how big your razor saw teeth are, this can work for very small wire - i think that I was using 0.25mm wire at the time.


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