Lighting

The lighting on the layout is all located on the Engine Shed. The shipyard itself had very little lighting so anything on the model has been added in the “heritage” phase. I did try some lamp standards but they didn’t really look right so I abandoned them and put them back into stock for another project.

I’ve used two types of LED, both from Kytes Lights. On the outside of the shed are two of their Double LED Wall Lights whilst the interior lights (which won’t be seen) are the Prewired Nano 0603 LEDs in Warm White. The connecting wires on these are extremely fine so I decided to solder some slightly thicker wire on before they connect to the controller.

The LED lighting on the layout is controlled by a home-built board that uses an MCP23017 I2C interface chip (the same as used in the bought in IO board). These have a limited switching capacity so I added a Darlington Pair IC as an electronic switch; this is old-fashioned technology but it works. Building the board took me a couple of attempts and it’s not pretty but it works. One thing I can do using this control board is code lighting effects. Fluorescent tubes don’t just “come on” they often flicker when switched, I’ve been able to replicate this.

The exterior lights and one
internal light in action

Fluorescent light effects, the final light has a failing starter
These may be reproogrammed later

Although the MCP23017 has 16 outputs I only needed 8 for this job so I used a single 8 channel Darlington Pair chip. The layout is fairly self explanatory, the links to A0, A1 and A2 are to set the I2C address. I made one mistake, the 0.1” spacing screw terminals used for the lighting wires cannot be stacked together and I didn’t buy any 8-way ones. Fortunately I only needed 7 connections so simply left one unconnected.

The lights used require a resistor in line with the power supply to run on 12v, which I included on the control board. I used the suplied resistor values as  starting point but experimented with higher values to get the effect I wanted. One thing to be noted is that this circuit switches on the 0v line not the 12v, however the resistors can be inserted in either.

Python Code

TBC

Stripboard layout for the
lighting controller

The actual controller board