Making Simple PCBs

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 3 PCBs above are all based on glass fibre PCBs. The one in the middle is the focus of this article. It is a Power Supply.
The other 2 boards are produced by the MERG (Model Electronic Railway Group in the UK). Members can buy these boards either as a kit (with all parts) or just the PCB for the owner to purchase the parts and assemble. The latter is what I have done in these 2 boards.
In these complex PCBs, a series of “components” are connected by conductive “tracks”. The components are soldered to the PCB through holes in the board.
In simple terms, the one on the left operates up to 8 servos which can be controlled by the one on the right. The latter handles input from switches.

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.
    To do a simple divide on the surface of copper clad PCB you can use a home made (left) or purchased mitre box (right).
    Just make sure that both segments are electrically isolated using a test lead or a multimeter on the Ohms range.
    To make the PCB on the right, cutting with a saw, as described above, will not work.
    A cutter such as a dental burr or a “Dremel” engraving cutter such as this one is needed in a rotary tool or drill press.
    This one is a #111 engraving cutter but I think #105 or one of the
    others as shown on the Dremel Site should work.

     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.

    This is the circuit diagram for the project described above including the “pinouts” of the 3 leg 7805 voltage regulator IC. Feed it with 7-35V DC and it will deliver 5V DC. The function of this board was to provide 5V to power the servos controlling my points.
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 Post to 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.

The example above is the rear face of a control panel (see the Post on Control Panels). Several pieces of PCB have been attached to the back of the acrylic panel material. The long strips distribute a connection to the DCC bus. This is used to operate the LEDS, shown later, which reflect the setting of the points switches and the solenoid position. The smaller squares terminate the connections from the LEDs via 1k resistors.
The PCB here brings in the connections from the module that controls the point switches shown in the first photo. The connecting cable is called “rainbow cable” and sells from suppliers like Jaycar in 16 wire ribbons. Other suppliers have even wider cables but they all repeat in batches of 10. This cable makes figuring out which wires go where, much easier.
Strain relief on the cable is provided by clamping an additional piece of 2mm plywood. The mounting ply and the PCB are epoxied to the recycled picture frame housing the panel.
The panel shown above is now complete and ready for testing. At the back, the LH PCB connects switches to the panel. This board was made using techniques shown above.
The right hand board is a piece of commercial strip-board sometimes known as Veroboard. This board is bringing in connections to the frog from 8 points. This signal is used to set indicator LEDs showing which track is “set”.

This gives some idea of what the panel does – the LEDs indicate which road is set. The switches also indicate the road but the LED is easier to see and actually indicates that the road has power. The switch on the right is replicated on the next panel and can be controlled from either panel.

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Rick Fletcher

Born in the steam era and developed an interest in railways when given a clockwork Hornby "set". Surrounded by steam when travelling to school (by train of course) and holidays were always by steam train as we had no car. How lucky was I?

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