Monday, 27 February 2017

Let there be headlights

One of the diesel kits I have has a hole at each end for headlights, it seems a shame not to have a go at making them work, so I ordered a pack of tiny surface mount LED's from Ebay (pre-wired). Quickly mocked up with a resistor on top of a Kato chassis they worked...


Over on the NGRM forum Harry Manthekis had posted a circuit he uses for LED lights, which uses a tiny chip to regulate the current and small capacitors to remove any flicker. My simple circuit certainly suffered from flickering, and varying brightness as the controller speed was increased, so I figured it worth trying Harry's idea.


The LM334Z gives out a regulated current ensuring that once the operating voltage is reached the LED's run at constant brightness, the resistor "sets" that current and I found 100 ohm suited me, not too bright. The capacitors ensure no flicker (especially useful with a feedback or PWM controller). Harry's circuit connected the cathode (-) of the LED to the - side of the rectifier and capacitors, however I wanted two directional LED's and realised that grounding them to each of the motor/pick-up connections would mean only one would light, depending on polarity. I've not shown the suppression capacitor accross the motor as it's part of the chassis, but I'm told it should be present to protect the LM334Z chip - especially from high frequency track cleaners.


It took a while to figure out how to assemble the parts in a compact space, I'm sure there must be smaller rectifiers! I will trim the LED leads once installed in the loco, but here's a trial run. Note one LED lit (on the left).


And with direction reversed, here's the other one lit. They do light much more steadily, so the extra circuit complexity is worth it.


With the circuit removed the means of contact can be seen, it will be mounted inside the body of the loco and the two springy contacts touch the pick-up strips on top of the Kato chassis. I'd removed the capacitor while fitting the electronics, it's since been replaced out of the way of the contacts, and the circuitry protected with much more insulating tape.

Right, on with the body preparation...

Tuesday, 21 February 2017

Narrow Gauge South West - The Final Curtain

After 25 years of holding the Narrow Gauge South-West show in Shepton Mallet, the organisers (the Small and Delightful Railway Group) announced that this year's show would be the last. It's not a show I've managed to attend often, being a fair trek from here, but I exhibited Awngate their a couple of years back, and really enjoyed it. With the final show promising to be super-sized with around seventy layouts (yes, really), I decided it was worth making the effort!


One of the stars of the show was Pempoul, a stunning model of French Narrow-Gauge in 1:50 by Gordon and Maggie Gravett.


Bridport Town and Charmouth by David Taylor is a well-known O-16.5 freelance model, that has featured in Railway Modeller, with that difficult to find "atmosphere!.


Devil's Bridge by Eddie Field is a relatively new layout in 009, capturing the feel and space of the prototype really well, set in an earlier era.


Another new prototype 009 layout but set in the present day was Launceston Steam Railway, by Richard Holder - instantly recognisable to anyone who has visited the line, and modelled to a high standard.


At the other end of the fidelity scale was Hobbiton End, a model of Middle Earth in 5.5mm scale by Simon Adelsee. Obviously built with a sense of humour, it has also been built with much thought to get the "feel" right, and to a high standard of modelling too.


As well as browsing the show I spent a couple of hours helping my friend and Sussex Downs group member Martin Collins with his superb 009 layout, Llandecwyn.

With so many (excellent) layouts at the show I can't go over them all here, but I can say the trip was well worth the effort - and with the bonus of chatting to many familiar faces too. But if you do want to see more, there's a large set of photos here.