sharris

Could it be because this part of the forum is called "Handbuilt track and Templot"?

276 didn't even appear in the Wimbledon Smiths where I usually pick it up. I have a feeling Smiths has deserted me. Heaven knows, I'm miserable now.

Quite some years ago, our company wrote some software for a client who wanted to demonstrate it at conferences, and being new software, we were to be on hand to do the demonstrations. The client plugged in their computers on their trade stand at a European conference where they were to debut the new software, and BANG - guess where they'd been the week before and forgotten to change the voltage selectors back!

Funny - I have a desk lamp that runs off 240v and the power switch and cable to that are quite light weight. Do you perhaps mean it's quite hefty because it has to pass a lot of current? (somewhere in the region of 3A at 240V or 6A at 110V for a quite generous AT PSU - less if you keep to the 250W you mentioned above). What is most likely to electrocute you with an external switch hanging on a wire is the mains line voltage exposed on the connections on the rear of the switch - you should shroud the back of the switch (often you can find an appropriate shoe to fit) to make sure that connections cannot be touched. If a switch really needs a protective earth, I'd rather it had an earth wire connected to it, than relying on the enclosure to provide a good path to earth.

Remember that the PC industry transitioned from the AT to ATX form factor in the mid to late '90s so an AT PSU you might find on your favourite auction site is quite likely at least 20 years old, pulled from old equipment and may now be of uncertain electrical condition.

For my current build (and if you cross-reference some of my other threads you might suspect that I'm toying with designing my own controllers), I'm considering using laptop power bricks to bring the mains down to something useful. The most common will put out about 3.something amps at between 14 and 19 volts, depending on the type of laptop (generally about 50-60VA) - should be sufficient for my fairly modest requirements - since I'm using Tortoise motors I don't have current surges on point switching. Other advantages - completely enclosed, certified (assuming it's come from a reputable manufacturer) and, if necessary, easy to PAT test.

Incidentally, a question for 1960s/70s Triang and Hornby experts: Was the searchlight wagon ever sold without the searchlight and control room as an ordinary well-wagon? (I've seen pictures of it had a variety of other BattleSpace loads) I had one as a kid, but with a different load (girders I think), but all the searches I've tried end up back at a Battlespace wagon, or a smaller 8 wheel well-wagon. I'm beginning to wonder if I had a second-hand one that had been repurposed.

A bit over a tenner these days according to H&A and Peco, assuming you're going to build it more-or-less as-is from the kit. Although I suppose you could always ask about a bulk discount if you were going to buy 50!

Wandering off the topic of connectors, but as an aside on the topic of rationalising your components, when I was studying electronic engineering, my tutor told me about his colleague who was colour blind, and in all his circuit designs had rationalised his choices of resistors down to the few that he could make out the colour code bands of.

One thing I've learned from all the IDC connectors I've assembled (mostly for ribbon cables of various types) is that IDC connectors and wire that's too thin for the connector's specifications is not a reliable combination, and bodging isn't a good option. How many combinations of wire sizes does one really need, and can't they be rationalised to some 'house standard' so you don't need every combination of connector?

Modelling the ‎Listowel and Ballybunion Railway would solve a lot of these problems.

A quick perusal of the Farnell catalogue reveals that Scotchlok connectors come in a variety of sizes to suit different wire gauges - would it not be better to choose the appropriate connector for the wire?

https://www.expertskiphire.co.uk/who-invented-skip-origin-and-name ... fascinating. You may want to skip to the section about the UK (see what I did there)... they claim the modern skip was a 1960s German invention - I'm too young to remember much of the 60s, but I'd guess late 60s would be less of a novelty than earlier. Apparently 6 cubic yards is classed as a small builder's skip these days. Edit: Nile - you just beat me to it!

Are there any signs of wire coming from the lights down to the base, and then cut off at the base? If so you might be able to do a bit of base surgery to expose what is left and connect a supply to them. This video should give you an idea of what it looks like when intact. https://youtu.be/UwEYApR_10s

That's not really comparing like-for-like though. DCC chips sit just cm away from the motor in a fixed relationship instead of being some metres away with a wiring geometry between the controller and motor that may well change as the loco is moving and at the throw of a point. The use of PWM is also an easy way not to have to manage throwing away the heat within the confines of a loco body that you might have to do with a linear amplifier DC motor controller, and intrinsically gives you an 'off' time-point to sample BEMF.

... if you're modelling US railways, maybe - they would look as wrong as any other type of automatic coupling on UK rolling stock of the 1930s.

I can see they might lead to some interesting operational puzzles if your layout has a reversing triangle or loop and you like to do a bit of shunting.

D1890 is an earlier version of the longer brake van with the half-height panels on the ends of the van sides rather than towards the guard's compartment. D1659 is a plain sided (no duckets, no half-panels), 20' over headstocks ex-MR design - a kit is available from Parkside.

The correct length over headstocks is 24' (96mm in model terms) and the correct wheelbase is 16' (64mm). pictures of the Hornby version show it with a number (730386) in the correct range for an unpiped D1919, the LMS liveried version of the Wrenn wagon number (730973) is correct for D2036 - the principal difference between the two diagrams is the extra width of the duckets on the latter. Essery's LMS wagons Vol 1 has a photo of 730386 indicating the correct bauxite livery - small LMS lettering above the running number rather than the large lettering on the Hornby model. Hornby's more recent version R6768 has the correct livery. The Wrenn wagon suffers from large letter syndrome too.

You don't say what your sampling rate was, but I don't think the CPU would have too much trouble these days with the maths of differentiation (particularly the DSP PICs) in the time interval available. Your sample-hold is giving you discrete time-sampled signals like the PIC would do, the only difference would be, particularly with the second differential, that quantisation steps in the ADC would come into play.

There's quite an involved discussion of the reversing and sound effects control system on another forum - it's a lot more complex than I was expecting! https://ogrforum.ogaugerr.com/topic/which-3-rail-trains-will-run-on-straight-dc

If I understand this correctly the controller has to be a good constant current source, with the current being monitored by a sense resistor and differential amp to set the regulation level - electrically can we call the regulator a 'programmable zener' (an analogue for possibly the simplest form of shunt regulator)? One thing troubles me - I don't know about n-gauge mechanisms, but in larger scales you might have a power hungry Dublo locomotive on a heavy train and a modern loco running light engine on the same layout - for the same demand speed (current) you might have greatly different motor current requirements and your controlling current will have to accommodate the highest common denominator. Is that not inefficient if you have a low current efficient motor and the regulator is having to dump most of the current as heat? Effectively every locomotive becomes inefficient as they have to draw the same current as your most power hungry loco on a heavy train, irrespective of motor efficiency and train load. Am I missing something?

Shhhh... we can't have the thread getting back on topic

Considering the variety of output waveforms that come from different types of 'DC controller' it's a bit rich on a model railway forum saying something can't be a DC motor

Nahh, I'd used synchronised atomic clocks in the locomotives and controller, and terahertz clocked counters to measure time-of-flight between the RC transmitter and receiver. Although, getting back on topic, I get the feeling that the original poster didn't want to cram his locomotives full of electronics, hence the various options of magnets, barcodes and RFID chips that could be glued to the bottom of the chassis.