RobjUK

Yep, it could just be that I'm not used to working with such coarse stranded types... We normally only use tri-rated cable in the general gear we work with, which looks rather larger when stripped. I'll try the old wire in a 25mm crimp tomorrow, just out of curiosity... Re. the other answers & links - thanks, I've found many different pressed crimp lugs but none with the rigid structure or matching dimensions of these. The original set are getting re-used. ps. To clarify, we are rewiring the body & chassis, not the actual bogies/motors - the connectors we are working with are in the body, to match up to the existing bogie motor tails.

Hi Jim, The motors in the bogies are fitted with flying leads & the groups of connector in the body/chassis are well anchored within a foot or so of the cable ends, so fairly well isolated from any motor heat. The cable we are using is 150'C rated as well so I don't see any operational problems in that regard, just cosmetic with the soldering heat. Stripping the old connectors down ready for desoldering was almost like an mini archaeological dig - many decades worth of differing types of insulating tapes, from PVC through sticky fabric to gutta percha or similar soft rubber & revealing the original cotton braided rubber cable - then the extremely weedy looking copper core in that; it's supposed to be the imperial equivalent of 25mm^2 according to the original drawings, though it seems rather smaller..

@iands - thanks for the link, there are some interesting ones there, I'll have to see if there are any with appropriate dimensions. @Davexoc & jim.snowdon - I realise the existing ones are soldered, I just don't routinely carry my 150W iron or a blowlamp in my toolbox... The main reason I was hoping for a source of new ones is that the amount of heat needed to properly flow terminals that size does not do PVC cable much good, it's not like an electronics joint where you only need heat for a second and it can't travel far in that time. A good crimped connection is much faster, neater & no burning plastic fumes.

Hi, does anyone know what this style of two-bolt cable connector lugs are called - ie. what to search for to find a supplier of compatible parts? I've searched under every description I can think of and not been able to find anything similar, with solid bodies rather than just flat tags. I'm rewiring a vintage English Electric built tram and these are used for the connections to the bogie traction motors. The owners interchange bogies for maintenance, so the connections need to be compatible; I can't just replace both sides with standard single hole terminal lugs. As a last resort I can try to remove the connector lugs from the previous cables but a source of new ones would be very useful! Thanks, Rob.

Phil, I have to disagree with some of your earlier info as posted above. Those values allow a fault trip, but in reality the actual maximum wiring resistance must be a tiny fraction of those values for proper operation. You may have intended that but it's misleading at first glance. For the controller to deliver it's maximum non-trip power to the locomotive(s) on the layout, the resistance must be low enough so the voltage drop is no more than a fraction of the supply voltage; the values as above would allow half or more of the supply voltage to be lost in the wiring with a motor running at stall near the current limit. The target resistance should be, say, no more than a tenth of those values at absolute worst case and preferably far lower. The 32/0.2 advised elsewhere for the supply bus should be OK for most smaller layouts / controllers, that's 1mm^2 and about 20 ohms per kilometer. With eg. a five metre run of two wires the loop resistance would be 0.2 Ohms; that could be reduced by wiring "ring main" style. Some actual calculation info: Typical wire resistances, ohms per metre; for stranded wire not listed, use the cross sectional area equivalent: 7/0.2mm (0.22mm^2) = 0.096 16/0.2mm (0.5mm^2) = 0.039 32/0.2mm (1.0mm^2) = 0.020 30/0.25mm (1.5mm^2) = 0.013 50/0.25mm (2.5mm^2) = 0.08 To work out the voltage drop, multiply the ohms per metre value by the total cable length (round trip total; eg. two wires to a point 2m away = 4m round trip). That's the wiring resistance. (If you use a "ring main" power bus, work out for the total bus length then divide by 4). Multiply that resistance value by the controller maximum current rating and you get the worst-case voltage drop on the wiring. Ideally that should be less than a volt and personally I'd aim for a tenth of a volt or not much more... Example; a two metre run of 1mm^2 cable, 32/0.2 or 1mm T&E. Four metres round trip length, 4 x 0.020 = 0.080 Ohms. A smallish layout, with a 1A controller. At one amp, the voltage drop is (0.080 x 1) = 0.080V which is tiny and will have no effect. The same cable, a 5m run: 10m round trip so 10 x 0.020 = 0.2 Ohms. Say that's on an O gauge layout with a 10A controller; the voltage drop at 10A is (0.2 x 10) = 2V, which is not at all good! Thicker wire or a ring main needed. Any other gear connected in line, eg. current sensing devices for occupancy detectors, will add to the voltage drops. As Phil says, it needs working out on a layout-by-layout basis, but ideally with practical numbers rather than guesswork. Rob.

Hi, I received three 7mm figures from Hardys a few days ago. I've got to say, the detail and finish quality are absolutely staggering, they are amazingly good! Highly recommended. Unfortunately my painting does not do them justice, Rob.

How about 3D scanning some good bare chassis, mazak or otherwise, so patterns are available when needed? For one-offs they could be metal 3D prints, until enough of the same one are needed for it to be worth a run on a CNC. Shapeways advertise 3D printing steel and bronze, among other things. All bronze could be rather nice! Small 3D scanners are readily available, or it can be done with software only and a lot! of good high resolution photographs. eg. https://alicevision.github.io/ or https://demuc.de/colmap/ (for two free ones, there are many others).

I check in and look at all the DCC & electronics related posts pretty much every day, but I don't have any questions for this category for now. The bit of time I get for working on models is at present occupied with building a 7mm Class 55 & my posts are mostly relating to finding parts suppliers for obscure (to me at least) parts and materials.. [eg. True scale mesh for the roof fans, anyone?] I'll probably be posting somewhere around here once it's approaching complete - it's having dual loksound 5 XLs, (with Bif's Deltic sound) and each with its own ESU smoke unit, to give true independent engine control. I suspect that is going to cause some serious configuration headaches... Rob.

The simple sound chips in cards and some toys generally have a fraction the data storage and no CPU, just enough logic to send some part of the stored data to a DAC which feeds the audio output. They cannot play multiple sounds simultaneously or manipulate the sounds in any way. A loco sound unit has a rather powerful CPU, lots of data storage and enough processing power to change the sounds on the flu, as well as mixing two or more simultaneously. You can get a greeting card type IC in a conventional package to build in to your own stuff, complete with a demo PCB for control and connections, for a pound or so; eg. https://www.ebay.co.uk/p/Isd1820-Voice-Recording-and-Playback-Module-With-Mic/1388908318?iid=181925204925&chn=ps That particular one has a maximum recording / playback time of 20 seconds in "voice quality". If you compare that to a minimal tape recorder type device, a loco sound chip is more like a music synthesiser for overall complexity; eg. near something like this: https://en.wikipedia.org/wiki/Roland_Sound_Canvas In fact, considering they have been out 20 years, the CPU in eg. a loksound 5 is probably rather more powerful!

Hi, thanks for all the ideas & sorry for not acknowledging them earlier, for some reason I'm not getting notifications. I ended up with a set of white metal parts from PRMRP, the place I got the original kit from.

Sorry, that is incorrect. An R-C snubber or VDR can be used across the switch, but a normal diode would do nothing. The polarity across the solenoid coil reverses when the switch is opened while current is flowing, so a diode there conducts. The polarity across the switch does not reverse, so a diode there is ineffective; it would never conduct or have any function.

Having a reverse diode connected across the coil - aka a "flywheel diode" - should slightly increase the force of the solenoid, not decrease it. The current will continue to circulate in the solenoid coil for a short time after the switch is opened or power disconnected. You get a slightly longer duration of "pull" for the same duration input pulse; with a small solenoid the extra duration is likely in single digit milliseconds, but is there. And of course it prevents any back EMF spikes damaging the switch contacts or external electronics. If you want to reduce the switching spike without the extended pull, use a VDR (voltage dependant resistor) such as a "zenamic" instead, rated at the same DC voltage as whatever power supply is in use. We use those in electromagnetic clutch controllers to give the fastest possible drop-out, without excess back EMF spikes.

The coupler - photos (and .stl attached). At 1:1 scale it's rather large, but it should be possible to scale to 75% or 50% and still work, with appropriately smaller screws. The diaphragm is cut from the palm of a nitrile rubber glove and just sandwiched in place between two coupler halves, with just enough tension to get rid of most of the creases. At 1:1 scale, M2.5 screws are suitable and the connection OD is 8mm with 6mm bore. The outside of the print is rather rough as I used a lot of support with it. The yellow & black object in the last photo is just a screwdriver used to keep it upright for an edge-on photo, not any part of the thing. Pulse3v4.stl

I mentioned in the DCC sound category a few weeks ago that I was planning to try an experiment to see if the output from a smoke generator could be made to pulse in time with a low-revving diesel loco engine. Richard Croft's "dancing speaker" post of February 26th was a confirmation that a suitable bass speaker should be capable of moving enough air volume to modulate the smoke plume from a smoke generator. It's taken some time for me to get the parts together & set up a suitable sound plus smoke config on a Loksound 5 XL with an ESU smoke generator, but I think it proves the concept - though it needs some tweaking and tuning to be fully practical for installation. eg. I think a speaker with a low-pass filter would work better specifically for this purpose, so only the very low frequency of the engine firing rate is really passed to it strongly, rather than the whole audio spectrum. That would also allow some independent control between the air pulse intensity and the sound volume. With the speaker in the test, too high a volume causes so much air displacement that smoke is emitted from the smoke unit fan. Another reason for the coupler and T setup (which will hopefully be implemented in my build) is to route some sound output via the loco exhaust, both to add to the realism and put the speaker vent on the other side of the body metalwork from the speaker cone for better bass isolation. Two videos below. The first is a better view of the overall smoke output and although the pulsing is not extreme, I think it shows quite well that it is producing slight smoke pulses in time with the engine sound, and the occasional smoke ring can be seen coming away from the main smoke cloud. The second one has the camera too close in and is not a particularly good view, but it shows an engine start part way through with definite pulses of smoke as the engine fires up (though the smoke then stops, probably due to my total lack of knowledge on how to properly configure a smoke unit...) Test setup: Loksound 5 XL loaded with ESU's Class 08 sound project, plus my first attempt to configure an ESU some generator, which is probably very wrong.. One of these speakers, coupled via piece of brass tube fitted in the port & some bits of silicone tube: https://www.ebay.co.uk/itm/263597184299 Home made (3D printed) diaphragm coupler/isolator in line with the speaker port (to prevent smoke crud getting in to the speaker). 8MM plastic "T" piece, connected above the smoke gen and tube link from the diaphragm coupler to the branch. I'll upload the coupler details and STL file in another post. Note that this is purely a hypothetical "because it's there" experiment for me; the loco I'm actually working on would never have a pulsed exhaust. However, I have the parts to hand & it will be some time before I'll need to finally install them, so experiments are possible at present! Videos:

Not those exact ones; other makes / types that are generally similar. They are in the "open frame" class, which means they should be mounted inside some other enclosure of some sort, so people (or children) cannot get to the terminals. The same applies to both, but one supplier does not bother with the disclaimer to cover themselves.

These are fanless and quite cheap - 12V 10A for just under £15. https://www.robotshop.com/uk/switching-power-supply-12v-10a.html Or even a 15A which also looks to be fanless for a slightly lower price; https://led.me.uk/12v-15a-constant-voltage-power-supply-for-led-strip

Some that are over 50 years old can be converted just as easily as more modern locos. Give details and/or take some photos and I'm sure you will find someone has done the same or a similar conversion already.

Hi, spotted this at Birch services (M62) yesterday (9th April 2019). No idea about it, just posted in case its of interest to anyone.. RJ.

The last couple of photos; the overhead shot of the prototype is a screen grab from a youtube video by "ecksfilesbonyuk8". Link to the fans I bought on ebay: https://www.ebay.co.uk/itm/Gdt-Lüfter-25mm-25x25x7mm-DC-5V-0-2A-Mini-PC-Computer-Cooling-Gehäuselüfter-Fan/322444596348

Hi, I'm working on a PRMRP 7mm brass Deltic model. This came with etched brass "fans" for static mounting, which to me just do not really look the part. I'd like rotating fans, but ones that look reasonably in keeping with the prototype. Searching on ebay, I found some 25mm fans with seven blades - not quite perfect, but the visual impression is good. Once I received them, the outer duct diameter was slightly smaller than the Deltic roof opening and did not look right; plus the roof curve meant they were a poor fit. However, the whole blade and motor unit is only held in the outer frame by three thin mounded spokes, They can be cut at the motor hub to separate the motor and blade from the original frame. I've 3D printed some simple ducts, 25.4mm internal diameter to match the roof cutouts and with a 50mm radius curve on the top to fit with the curve of the roof. With the fans painted an appropriate shade of red, I think the impression is pretty good - though I also think need a finer mesh grid than the one supplied with the kit. Hopefully these can be used with other 7mm locos that have (or should have) roof fans. The fans are 5V, I intend to connect them in series pairs with a resistor to limit the speed to a sensible rate & power them from a function output on the decoder. Photos, plus the .stl for the duct as an attachment. It should be possible to scale this if a slightly different size is needed for different locos. The parts are only being held in place in the loco body for the photo, there is a lot of other work before it will be ready for them to be permanently installed. FanShroud.stl

See page 19 of the manual. http://www.esu.eu/uploads/tx_esudownloads/51982_LokPilot_V40_Family_ESUKG_EN_User-manual_Edition_3_eBook.pdf Looking at photos of the 54611, the top diagram is the half of the decoder opposite the wiring end. The group of five solder pads above the large IC appear to be the connections in the manual. See the photo here; pads at the top right, the way that is orientated:

I've got a batch of white LEDs from RS Components, their part number 175-1962 ["Duris E 2835"]. They are an ultra-bright surface mount type, so high output that when I was experimenting with resistor values for loco illumination I ended up with a 10K series resistor for a headlight and 100K for internal cab lighting. That's roughly 1mA for very! bright and 0.1mA for moderate brightness. They were about £7 for a pack of 100. The LEDs are about 4mm square and quite easy to solder thin flying leads to. Using those you could easily run a hundred from a basic decoder, without even getting in to series connections.

That is a myth. Nylon and all normal engineering plastics are _not_ damaged by conventional mineral oils or silicone type lubricants. The commonest cause of failure of nylon gears is dehydration. Nylon 6 contains about 2.5 - 3.5% water under ideal conditions. If it dries out over time due a hot and low humidity environment, it both becomes brittle and shrinks, which can cause cracking. Lubricant compatibility info; see page 5 for the table: https://www.ecllube.com/resources-for-engineers/tutorials/ECL_Tips on Lubricating Plastics.pdf A couple of examples relating brittleness to moisture content: http://www.atlanticfasteners.com/simple-remedy-for-dry-brittle-nylon-parts/ https://onlinelibrary.wiley.com/doi/abs/10.1002/adv.1989.060090206

Just for info, "Designcad" is pretty good. I've used that for 2D work for many years and it has full Autocad DXF & DWG compatibility. It's not free but $49 as a one-off purchase. https://www.turbocad.com/designcad/designcad-2018.html

Hi, minor but trivially annoying bug, if an admin can have a look at it: In the member info at the left of each post, the word "Location" does not have a space after it, so the members location text runs in with it... It's probably a definition in the board language files, if this setup is anything like the ones I have experience of. Rob.