To produce the smoke I've fitted a Seuthe smoke generator inside the chimney (it's about 1cm from the top). You can see the smoke generator in the photo to the left; this was taken while I was testing how it works. It is actually very easy to use, you simply add a small amount of smoke fluid to the chimney using the supplied syringe and then apply electricity; it requires quite a bit of juice and I'm powering it with a 19V DC supply using the adapter from the cheap OO gauge train set I bought last year.
The flickering fire effect is a little more complex. Now I'm sure that I could probably have bought something for this purpose but I decided I'd prefer to build my own solution. Essentially the flickering is produced using five bright (6 million candles each) LEDs, 1 red and 4 yellow. These LEDs are connected to a small micro-processor (this is essentially a shrunk down Arduino) that runs a very simple piece of code to flicker the lights: randomly choose one of the LEDs, randomly set its brightness and then wait randomly up to 50ms before starting again. It's simple but effective, although I think it could improved by tweaking the minimum brightness of the LEDs.
Two simple additions which, I hope you agree, really help bring the factory to life.
