Izzy

J15 construction resumes It seems it’s over a year since I last wrote anything about the J15 build. This it turns out is because work stopped in early January of last year to await the turning of items and it’s only now that I have eventually got back to it. Despite the fact I was at that time waiting for boiler fittings it is actually the tender that has now been completed first. This in itself would not have been possible without the kindness of fellow 2mm association members @2mm Andy & @queensquare in offering the necessary tender axlebox castings from their stocks which were no longer available in shop 3. Thanks again chaps. Another reason the tender has been finished first relates to the need to tuck the small Zimo decoder and stay-alive pack in it. If I thought fitting such into previous locos such as the Hunslet 05 and J69 were a challenge they have proved comparatively easy by comparison. Part of this revolves around the fact these exGE tenders were quite small in comparison to others and once the 7x16mm coreless motor was inside there wasn’t much room left. Here are size comparisons with a LMS 4F Fowler tender and an Ivatt 2MT. Since it seemed to be of interest I’ll deal again with this aspect in case it helps others facing similar problems. The only space to fit the decoder was behind the motor in the rear, just enough for the tiny 8x6mm Zimo MX615. Goodness knows what I would have done without these being available. As with the J69 the aim was to sit it on top of one of the flat 16v 470uf tantalums I had obtained. But once I added the Zener and diode/resistor into the mix I found it was just too tight a fit into the space vertically, which was just under 6mm deep. So somehow I had to try and reduce the ‘thickness’ of the decoder/stay-alive sandwich. As I had to obtain more bits anyway instead of mini-melfs I found sources of SMD components. SMD100R resistors (which I’d used before) plus SMD schottky diodes and SMD Zeners. Although not massively smaller they were enough to allow the pack to reduce so it would fit. The SMD ones are in the front in this shot. I was able to put the Schottky and resistor on the side to help lower the overall height. A side on view. And one from above with the tender body in place. Although five J15s were fitted with side window cabs and matching tender ones specifically for working the Brightlingsea branch and Colne Valley lines with tender first running, and were thus Colchester based locos, I have instead chosen to keep the loco as a normal one so the tender just has the much more common tarpaulin rail fitted to the tenders for tender first working in poor weather. Now I am satisfied that the loco & tender run okay under DCC on Priory Road, something I was concerned about, finishing off the actual loco can commence. I should add that for this testing with the plain metal bodies tamiya masking tape was used to isolate the bodies from the split frame chassis. This will not be needed once the bodies are painted. I find a couple of coats of paint from the Halfords rattle cans, primer followed by matt black, provides all the insulation required between them. Bob

First off you really need both a resistor and diode in circuit and in addition a Zener will help limit the current to the capacitor. If you look around online several circuit diagrams and component suggestions will be found. I use a 100R SMD resistor combined with a Schottky SMD 40v diode and a 16v Zener. As to decoders well, I now only use Zimo. The MX600 at £25 is still available and will be far better. Bob

J15 with two speakers Well, it's been a while since I last posted on this thread. It isn't that things haven't happened, All Saints East itself has been completely rebuild for a start, and new items in the form of a couple more locos added, but the main focus has been elsewhere with another scale/gauge. However the making of these new locos and fitting them with sound, (a J68 from an etched kit and a Thompson L1 using a Hornby body on an etched chassis), brought to my attention that the only tender loco, the converted Hornby RTR J15, didn't sound right with the sound clearly coming from the tender and not the loco. This wasn't readily apparent when I first fitted sound to it after the conversion to P4 but slowly became apparent over time when run alongside the other locos. The question was, what to do about it? I'm afraid I am one of those people that can't leave things as they are if I find something that's not right and isn't to my liking. There was nothing wrong with the sound, the J15 project from Youchoos, indeed it sounded great (and stills does) with a few tweaks for personal preference for individual sounds levels. Now I'd fitted sound to both these new steam locos by fitting speakers into their smokeboxes and it began to occur to me that this was what I needed to do with the J15. With a speaker already in the tender and having read and posted questions about twin 8ohm speaker set-ups it seemed quite possible to do and especially as I had fitted a Zimo MX645 which can cope with this in either speaker wiring formation of series or parallel, having a 4-8ohms output. Speakers wired in parallel halve the impedence while in series this doubles. So two 8ohm in parallel are 4ohm while in series it becomes 16ohm. It seems the lower the impedance the louder they are and visa versa. The speaker impedance must obviously match or be less than what the decoder can provide. So in parallel is not possible for those that can only provide 8ohms, which is the vast majority of Zimos. ESUs are all 4ohm I believe. The big issue was finding the space. The Hornby J15 has a cast metal footplate and upper body in two halves for weight which is great but what space remains is stuffed with the chassis and motor etc. There is no empty space at all. Eventually after measuring it all up I realised I could, just, squeeze one of the small 15×11mm planar speakers I have used recently into the smokebox standing vertically, but only if I was able to cut out the large chunk of metal that sits there behind the smokebox door. It took me quite some while to pluck up the courage to attempt this, the ever present danger of just wreaking the complete loco not being far from my mind. Because finding a spare body would not be easy (probably impossible) should things go pear-shaped. Trying to work out how to actually cut out this metal section also took some time. If only the smokebox door came out…..and I could get the boiler/cab off the footplate…. In the end one day I just took the plunge, parted the loco and tender, and took the body off the chassis. After removing the screws under the cab floor I managed to slowly lift the cab away and by gently levering the cab/boiler up/down it started coming away from the footplate. It took a long time as I didn’t want to bend/warp/crack the footplate. The front slips under the footplate and this is what the chassis screw goes into. It was the middle part of this tall square pillar I had to remove, well almost all of it actually except the very bottom bit with the screw hole. As there was a gap either side which shows the rear of the smokebox door I decided to push my luck and see if I could force the door out from the rear. I guessed it was glued into place. It’s plastic, one of the few parts that are. Just when I was about to give up it flew out of the front with a crack and ended up on the floor feet away. Given the sound made I thought perhaps I’d smashed it, but no it was intact and undamaged. That was lucky! With it removed there was then easy access to the pillar and so I chain drilled it top and bottom to remove the bulk and cut it out and then spent a long time cleaning it all up with burrs in a mini drill and to get the square corner shape into which the speaker would fit. I had to cut away the pillar below the front of the smokebox which was a tricky task to complete. Once done it proved possible to get the speaker into the space but only a flat piece of plasticard could be added onto it to make a sealed enclosure. After soldering on the wires I wrapped it in Tamiya masking tape for insulation against the body, not wanting electrical shorts of any kind. This tape was also used to hold the wire runs to the inside of the boiler. Initially when all done and wired up I found the larger Zimo speaker in the tender still overwhelmed the other volume wise, so replaced it with another 15×11 planar to get an even sound output. This worked nicely. Now it seems as if the sounds come from the loco itself whichever direction you listen from. So a lot of hard work but worth the effort. Bob

I guess all the magazines are going to miss the annual advertising income Hattons used to provide, the often multiple pages.

Experiments have continued. It seemed just adding the small planar in the smokebox didn't really have the desired effect, the sound volume of the larger Zimo dumbo in the tender overwhelming it. It was better, but still noticeable. So then I removed it and fitted another of the 15x11 planars in it's place, the idea being they would/should match and thus balance out better. This seems to have worked out. The sound now just seems to come from the loco as a whole rather than a specific area of it as before. This might be helped by the fact the one in the tender is right at the rear of it to match/counter the loco one being right in the front. This is good given all the work I had to carry out on the loco body to obtain the space for the speaker. Even in parallel at 4ohms however the volume level output couldn't match that of the single Zimo dumbo at 8ohms. I had it set at 20 (cv266) for my needs in a small room and have had to increase this to 60. Part of this might be because there was no room to add an enclosure to the smokebox one so I didn't with the tender one either so as not to skew too much the balance I was after considering the space in it to act as a soundbox anyway. Bob

Yes, it does, many thanks. Luckily the Zimo concerned is a MX645 which can do 4-8ohms. So it looks like parallel will be what gets wired in. Bob

I've spent this afternoon testing the theory. Joined up in Parallel the speakers worked fine no matter which way around the wires were. In series one way they were both noticeably quieter one way than the other so that must be the way to judge when they are wired correctly. I got the impression that in Parallel they were louder than in series but this might be because it was all done in the open. Now I am trying to carve out enough space in the J15 smokebox area to fit the small planar, an ESU 15x11mm, when I will test both setups again to try and determine which is best, and if the second speaker actually makes much difference. Bob

As there are no markings on any of these speakers and they are both of similar design, flat with sprung contacts, and able to be fitted into different sized enclosures, I guess I could assume that they are given ‘standard’ polarity I.e. the same orientation, and then go from there. Thanks for the helpful replies. Bob

Quite basic question I’m afraid but one I have not been able to find clear answers to with searches although I have tried. Maybe I’m a bit thick. I have a sound fitted tender loco, Hornby J15 with Zimo MX645 + Zimo 8ohm dumbo speaker, that I want to try and add a small 8ohm planar speaker into the smokebox because as it stands the sound is great, but does really seem as if it’s coming from said tender rather than the loco. I’m hoping that this might help balance it a bit better. As I understand it the MX645 is capable of driving two 8ohm speakers in parallel (4-8ohms at 3W) but I can’t seem to discover whether polarity is important or not I.e. if the wiring needs to be the same to both or doesn’t matter. And if it does, how to set it up, to tell what the polarities are etc. without blowing up the decoder amp! Can anybody advise please? Thanks, Bob

Looking on Rail-online I've found D5815 at Wath diesel depot in 1966. D5685 near Audley End. D5677 at Stratford 1967. All SYE & double arrows but most others seem to have FYE. I might have missed a few though. Bob

And I think this came about by the need to come up with a design that used just standard L/R hand points, all that were available for TT at the time. This was the driver from which it all developed IMHO. Everything past that just refined and adjusted it for other scales and needs. To my mind though it wasn't just about the track design, so simple and clever as it is, but the whole concept. A small folding layout that could be used and then packed away in a small space. Maximum usage from minimum hardware in terms of layout size, rolling stock numbers, and thus total outlay. The way housing is going these days, new builds where there are no garages and precious little other spare space of any kind, means ideas like this will become even more important than they have been in the past for many. Witness the growing number of 'shelf/plank' layouts now around. It has always been this way for me.

You’re right, they are PP3. Don’t know where PP9 came from so sorry, they are a larger 9v used in old transistor radios. Both are 9v where I guess the confusion originated. But really any fresh battery from a single AA/AAA up should run a 0-12v motor to see whether it runs at all, for a short while at least. Some really large ones might need 3v. Rechargeables drop around 0.25v so that has to be born in mind but are often good for anywhere between 900 - 1600 mAh or more.

Thanks, that’s good to know.

I’ve had a (BT) phone with Call Guardian for some years now. All cold calling doesn’t get through. Only rings for allowed numbers or announced calls. Just not sure whether the system will work when the line goes digital - if it’s VOIP compatible - or will have to get a new one.

Small N gauge motors like these should draw no more than around 60-100ma. I've had three N gauge going on a circle of track together and the total draw was 160ma. So a single motor should run quite fast on a new/fresh PP9 and still turn on one that's well run down. Can you test the current draw on a MM? I don't have any Dapol N gauge any more to test myself. When I did, a 66, 156, 87, they all had this motor design, ran well, and didn't get more than warm. Perhaps I didn't run them long enough to heat them up. It would be interesting to discover what they consume compared to the figures I gave, which apply to the Farish can motors and newer coreless cans.

Although some older design motors can run fairly hot I would not expect it of present day ones. Or only if they are under extreme loading. Running light/with no load, as in your shot, they should remain cool or barely warm at most. Is the combi a feedback controller. If so that might be having an effect.

If you want to add stay-alive then I would suggest you get 8-pin wired decoders. Easy to cut off the plug and then hardwire by removing all surplus wires. With 6-pin - where there is no common + blue wire connection - they use half wave for the lighting circuit through the black track connection. So then when adding SA you need to locate both the common blue+ and ground connection places, designated solder pads etc. Some have them, many don’t. With 8-pin there is the common + blue so all you have to find is ground for the SA. Much easier by comparison.

Glad you found it useful Jerry. This is one of those aspects that is difficult to convey in words and seeing says all that's needed. I just wish I had the skills to present things better. As far as the Buck goes it's now finished, or rather should I say that it now joins the queue - it's getting quite long - of those waiting for spring/warmer weather and painting. The final details of pipework along the footplate sides, injectors under the cab, lamp irons and destination board brackets now added. Any cab interior will wait until painting is complete. These isn't quite as much spare room as I'd hoped so it will be very basic. Here it is up against the N7/3. I am pleased with it's final weight. I have been able to add enough lead in the smokebox, bunker and tank sides that it's now 43gms. This is the same as the larger Farish Jinty. One aspect that did worry me for a while when comparing it with my other steam locos was it's size. For a while I wondered if I had produced the drawings size wrongly for these exGE tank locos are generally seen as smallish, yet in reality these last designs, and thus the biggest, weren't. It is smaller than of course the N7/3 but in some respects seems to loom over the Jinty at some angles and quite dwarfs the J15 in height and width. It's nice I now have a selection of scratchbuilt exGE steam locos in 2mm. Now I must really get on with the J15, the poor thing was started first of all the current construction and is the last to be got towards the finish line. I've had a few issues arising to solve with it, not the least being finding enough room in the tender to fit more than just the tiny Zimo MX615 i.e. some stay-alive in the form of the flat 470uf. It's going to be difficult. But also the ex farish 4F tender wheels look as if they won't last the course, the N/S plating on the tyres is wearing off and the copper under layer is showing even though they have hardly had any use. Current collection was thus pretty poor under plain DC until the loco was hooked up. I may have to replace them with 'proper' mk5/6's. But comparison with the J69/1 has shown up an aspect of the N7/3 that will be dealt with first. The lack of beading around the side and front windows. It looks poor and needs doing. Somehow I missed it when completing the loco and didn't notice it until now. Anyway I hope my relating some of the J69/1 construction, the making of parts, might help and encourage others to give it a go. Bob

Yes, the 4-pin is as you suspect just purely for motor control. You could probably remove the spare pins and plug what remains into the 4-pin socket. All that’s needed for many steam locos. Just make sure you remove the right ones…..!

With regard to the stay-alive aspect and 'just' using a single 470uf tantalum I thought I would try and make a video of the result. It's not that brilliant so you'll have to forgive the shaky and less than wonderful result but I hope it does - just - show the amount of run-on that exists. It's a crude way of doing it but I couldn't come up with any other that actually showed it clearly enough. Obviously more uf would always be better but it works good enough for me. Bob

Interesting the subscriptions for all the mags shown is roughly the same. I wonder where BRM stands in this, or such as the MRJ. Also what % are digital rather than paper. It’s interesting to me in the sense there is now no local newsagents in my area, the last closed in late 2023, and none of the smaller size local supermarkets stock any modelling mags at all, Tesco/Coop/Sainsbury/Aldi/M&S, 10 miles or more to the nearest that does. I often wonder what impact this might have on the hobby in generating new interest.

Thanks Tony. Compared with the 3D plastic versions and the home-made one I eventually made up for the N7/3 when they all fell apart in my hands I think they are quite nice. They do certainly look the part I feel. Here's a quick comp shot with the N7/3. I don't know if it would be possible to print them in a slightly softer material because trying to drill 0.3mm to take the pipes was near impossible. I managed to make a dimple to help locate and that was all. But it might be whatever is used. However I do find they take normal soft soldering with no issue so actually adding the pipes - some PB wire - wasn't the problem I expected and a good strong joint resulted. TBH it's nice such parts exist at all, so thanks. Bob

J69/1 details The work of adding the details has slowly progressed over the last week. I started off by trying to work out where all the bits needed to be and the holes required for them and then drilling 0.3mm pilot holes to be enlarged as necessary. In the end I counted 30 holes... so it took a while to do. Doing them in one go I find better than doing them at the time of fitting and then finding a detail already in place prevents the hole being made. It is for this reason that I now leave fitting chimneys and domes until last, finding they are either in the way or keep getting knocked and damaged in the handling. I also leave adding footsteps until the end for the same reason. I fitted the whistle first simply because in getting the holes in the right place it 'pinged off' onto the floor so I made sure when I luckily found it that it wouldn't do it again..... Then I made and fitted the clack valves, produced simply from 0.4mm brass rod with slices of 0.8mm & 1.0mm brass tube ( Albion Alloy). Since I need some for other locos I made a batch of six. I often make bits in batches when I know more will be needed in the future. All the details except the Westinghouse pump - a 2mm SA stainless steel 3D print - and etched handrails knobs - were made up from wire & tube of suitable sizes. It's all time consuming rather than difficult but does produce reasonable results. Working out the order in which to add the parts is key I find in not tying yourself in knots and it does tax my simple brain so it was slow going as the loco is 'busy' as regards pipes runs etc. I fitted the smokebox door next to enable the handrail fitment. The condensing pipework I made up on some paxolin before fitting. Nearly there The footsteps I always back with a narrower strip for strength before adding the steps themselves as I'm always finding myself bending knocking them in handling If I am not careful. I think you can just about see them in this shot. The buffers were from a batch I turned when I made the N7/3. The steps are small bits of sheet cut and bent up and then soldered into place. With the chimney and dome now added it's beginning to look decent. Like the smokebox door these were glued in place with cryno. I have always fitted them this way rather than soldering. It means when whitemetal castings are used and something isn't quite right there is a greater chance of getting them off and re-using/re-seating them. Not quite there yet though, there is the pipe runs along the footplate sides for the brakes etc plus the actual bufferbeam pipes. Bob

There are two different arrangements for the MS490. A direct connection for a small 16v capacitor up to 1,000uF, and another for complete stay-alive packs using the normal common + and ground. @John Besley There are some decoders that won’t read on a program track once stay-alive is added. Those I’ve encountered like this to date (CT & TTS) also need analogue running turned off to work, although I do this by default anyway. I have not encountered these issues so far with any flavour of Zimo, sound or non-sound, but I also don’t use large capacity stay-alive such as LaisDCC, nothing over that 1,000uF figure. This might also have an impact. With regard to the MX600 going duff I would suspect the stay-alive connections were the culprit and must be different to those I posted, the ground connection. It’s all a learning curve …….

Thanks Nigel, that’s interesting, and food for thought as usual. Bob