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 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.