I have never been happy with the fumes from lead based soldering wafting into my face. A properly fitted extractor hood would be ideal but I cannot justify the cost or space for hobby use. I know I probably should use lead free solder but I have never been happy with the finished joint in that either.
The simple device described below at least blows the fumes across the work area for dispersal, instead of up into my nose.I have recycled a computer cooling fan (12v 300mA) wired to a fan speed control which was also recycled. I notice that you can buy the simple controller on eBay at $3.40 AU from China. It is adjustable to give enough airflow to move the fumes. without being too draughty.My unit plugs into a 12v outlet on my workbench – also available for testing various MERG & other projects. TOOL Racking and Storage will be the subject of another post.
Printed Circuit Boards (PCBs) are possibly a step too far for many railway enthusiasts. However the material lends itself to many simple possibilities. What is PCB? There are two main types:
a board based on glass reinforced resin and coated with a thin layer of copper which is a good conductor and easily soldered. Some PCBs are double sided, ie. coated with copper on both sides. For our purposes, both could be used but there is not much advantage in double sided boards for these simple projects.
an earlier type which is based on a phenolic material, dark brown in colour and somewhat brittle. Otherwise similar to the above
The PCB we want to use is BLANK PCB which can obtained from on-line
or retailers like Jaycar® or Altronics® in Australia.
The rest of this post will focus on how to make simple PCBs even more basic than the one outlined above.
Rather than a Terminal Strip with screws:
The PCB on the right is about as simple as you can get (& cheap!)
It is divided into 2 discrete parts by making a saw cut through the copper cladding. Each half is a separate part of the circuit. One for the RIGHT rail of the DCC supply and the other for the LEFT rail.
A couple of screws hold it to wood in this case. It could have been glued (epoxy) to the wood or to the underside of a foam layout with contact cement. 2 screw holes are needed.
The copper is cleaned with fine wet & dry or a fibreglass brush. For ease of soldering under the layout, I made 10 small starter “blobs” of solder.
The pic above also appeared in the Track Feeder Post Whilst this one looks slightly chaotic, it shows a couple of other aspects:
the PCB has been glued to the base of the foam with contact cement.
the piece of PCB is super simple – the copper has been split into 2 sections by using a modellers razor saw (see below)
colour coding is obvious and important
the 2 CBUS wires (red & white) to the far right have been held in place using a low temperature glue gun.
the purpose of the exercise was to feed DCC power to 4 adjacent tracks on the turntable.
This is the finished product PCB.
It converts 12V DC to 5V DC which is required in some circuits.
The construction technique is UNUSUAL but SIMPLE to use for basic circuits. In effect a bit like modern boards which are made using SMDs (Surface Mount Devices) except that the latter are TINY, almost microscopic.
How to Cut the Grooves:
The “pads” of copper will form discrete parts, or “pads”, of the circuit for this 12V to 5V converter. Below I am using a small bench drill (or a rotary cutter like a Dremel) with a guide clamped to the left. To set the depth of the cutter, the simplest way is to adjust the cutter so that it just touches the surface of the copper, then slide the PCB away and place a piece of paper under the board which will raise it enough to route a groove. You will need to experiment with the thickness of paper but a thin piece is all that is required.
A slightly more crude approach, but one that will work, is to mark out the pattern with a pen and freehand cut the grooves. The electricity won’t mind if the edges are a bit ragged! But check that each area is not shorting to a neighbour with a meter or test lamp. Treat the cutting tool carefully with respect to SAFETY . Wear safety glasses. If cleaning up with a fibreglass tool, vacuum up any loose material – it has an attraction to entering your skin!
The NEXT STEP of installing the components involves SOLDERING so see the Soldering Postto reproduce something like the little power supply above.
At present I will continue this post to show how to use super simple pieces of PCB as an aid to wiring layouts and panels.
No … not that sort of bus!
In our case it’s a wire, or a collection of wires that carry an electric circuit or a data circuit.
In this example the bus is connected to a PCB strip in 4 places to simplify connection of the droppers to the bus.
I will have a post to cover using printed circuit board PCB for various purposes.
See: Making Simple PCBs
This an underside view of my layout with 4 bus wires in view.
A = DCC main bus; (heavy duty stranded copper wire) Red = rear track wire B = 12V; (H/Duty above) Blue is Positive and White is Negative C = DCC sub bus (in this case from the main bus to the YARD bus). This allows
me to easily isolate that section. D = MERG Can-bus which distributes the electronic data around the layout. Note that it is very thin as it carries low current signals.
Note also that the wires carrying a data signal A,C & D are all lightly twisted to lessen interference one to the other.
Note the colour coding – there is no fixed rule but RECORD your code.
Our problem is to get the track feeders through the baseboard, in this case FOAM, to the Bus underneath. EVERY piece of track must be fed between joiners. There is a special issue with foam.
Some sources indicate that the foam can react with the plastic on electrical wiring and cause it to break down. A wooden base board can just be drilled 6mm.
So, after we have drilled the hole in the foam (as shown here with the 6mm K&S brass tube drill still in place) we need to line the hole with an inert material.
Note the colour coding – there is no fixed rule but RECORD your code.
See the Post on DRILLING HOLES IN FOAM for more info.
Because this section of my track was using Expanded foam (not recommended) I had to clean the hole out with something that was a loose fit to get rid of all the little white balls of plastic.
This is not needed in Extruded Polystyrene Foam. See details on foam HERE.
The 6mm hole is an exact fit for a drinking straw. My preference is for the paper straws but they seem to have disappeared on the far South Coast so plastic ones will do.
Measure it to be 5 mm longer than the total depth of foam and underlay.
Coat the straw lightly with some PVA…
… and slip it into the hole.
Wipe off the excess PVA …
…and do the second one.
Now we come to the bit where you need to solder a wire to your track, take it down the feeder hole and connect it to your Bus wiring.
Shown below are the tools you will need for the top side. I have a colour code for the droppers – RED is the Right DCC track (or in my case, the REAR track closest to the wall in an around the walls layout). My front rail is fed with GREEN (because I had heaps of that colour).
In a module you just need to be consistent making sure that no swap-overs occur.
As can be seen at the top, I have a main DCC bus which feeds 4 sections – North (Carriage Works), South (Loco), East (Yard) & West (Station – “Bolgan Road”).
Each section is fed via a STOP LIGHT BULB in series with one feed wire. If there is a SHORT CIRCUIT, the stop light bulb will carry the load and LIGHT UP.
See THIS SITE for more info. Or THIS ONE.
If you are working on a timber baseboad, the feeder hole can be drilled between the sleeper (tie) ends under the connection point and there is no need to line the hole.
The photo above shows some of the kit I use when working under the layout.
1. a low level seat which can slide on the floor
2. a low level 240v light (LED) which has now been replaced by a similar size rechargeable LED work light,
3. soldering station,
4. wire strippers, knife, sidecutters (not visible) for removing the insulation from about 1cm of the Bus wire.
5. and, BEST of all – a locking clamp with a roll of solder attached so that it is easily accessible. See the post on Strain Relief to help you work under a layout.