RMweb Premium St Enodoc Posted October 15, 2015 RMweb Premium Share Posted October 15, 2015 In my world ( don't come in, it's a very strange place) the PSMT is still running ( well, in truth it is again) - I've seen an Airfix kit for a VW Beetle which will look nice rusting in some weeds. You will need an Ambassador taxi or three as well. 3 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 15, 2015 Author RMweb Gold Share Posted October 15, 2015 You will need an Ambassador taxi or three as well. Yes indeed. But where from ? Link to post Share on other sites More sharing options...
RMweb Premium St Enodoc Posted October 15, 2015 RMweb Premium Share Posted October 15, 2015 Yes indeed. But where from ? How about this? https://www.youtube.com/watch?v=P6N_4GXvlTs Doesn't say what scale but unless the chap has very small hands it looks a bit bigger than 0 gauge. Link to post Share on other sites More sharing options...
RMweb Premium St Enodoc Posted October 15, 2015 RMweb Premium Share Posted October 15, 2015 How about this? https://www.youtube.com/watch?v=P6N_4GXvlTs Doesn't say what scale but unless the chap has very small hands it looks a bit bigger than 0 gauge. This looks like the same model: http://www.ebay.com/itm/4-X-India-AMBASSADOR-Car-Toy-Model-Taxi-Collectible-Kids-Toy-Cars-Gift-Souvenir-/231505943792 The description says it's 5 inches long, 2 inches wide and 2 inches high. Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 16, 2015 Author RMweb Gold Share Posted October 16, 2015 ...and $49.99 ! Thanks for the heads up though, will start hunting for a cheap (er) one. Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 16, 2015 Author RMweb Gold Share Posted October 16, 2015 The prototype was 170" long. At 1:35 scale a 5" model would be 175" - which is , as you said, virtually ideal. 1 Link to post Share on other sites More sharing options...
raymw Posted October 16, 2015 Share Posted October 16, 2015 the ebay price is for 4 off. Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 16, 2015 Author RMweb Gold Share Posted October 16, 2015 the ebay price is for 4 off. Yes it is for 4, but I'd only need 1to help set the scene. Link to post Share on other sites More sharing options...
peter220950 Posted October 16, 2015 Share Posted October 16, 2015 (edited) In my world ( don't come in, it's a very strange place) the PSMT is still running ( well, in truth it is again) - I've seen an Airfix kit for a VW Beetle which will look nice rusting in some weeds. Well it's started already, before you even have a layout built you've started a gauge/scale war between 1/32nd and 1/35th, can you imagine the pages of angst and vitriol we are now going to have from the 'Proto Stubby SF' lobby.(Single Fine) I wouldn't mind but you haven't even got a gauge. Come on now man, make it one thing or the other or we'll have this thread locked before you have time to build the platform toilets. Peter Edited October 16, 2015 by peter220950 1 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 16, 2015 Author RMweb Gold Share Posted October 16, 2015 I may not have a gauge, but I have got double flanges ! 1 Link to post Share on other sites More sharing options...
Echo Posted October 16, 2015 Share Posted October 16, 2015 Yes it is for 4, but I'd only need 1to help set the scene. If the railway experiment doesn't work, you could always have the train static and moving taxis carrying the passengers away................................. Ever an optimist! Why not buy 4 and sell the others on Ebay? 1 Link to post Share on other sites More sharing options...
HAL 'O THE WYND Posted October 17, 2015 Share Posted October 17, 2015 (edited) Hi Stu, I think it's an excellent idea! I'm not remotely technical so I won't remark on any of that other than the reverse-minic idea (Nick Halliday? Forgive me if my memories gone - again!) It sounds dead simple and sprung pickups either side of the insulated centre could keep contact and even softly grab the rail; I'm thinking round-headed pins. Even I could mock up something like that. Otherwise, forgive me as - yeah, the time thingy with me as usual! - I read rather hurriedly, so I might have missed someone remarking on Google Images? I put the name into GI and lots of pictures came up. I don't know if any are different from the excellent ones people have posted, but it's a dead easy quick look. I found: - Again, maybe my impolitely swift look might have missed it! If you find this image on GI, click on it and it might even take you to more similar, technical ones. Anyway, I think it's a fascinating project you are well capable of. Regards, Tony. Edited October 17, 2015 by HAL 'O THE WYND 2 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 17, 2015 Author RMweb Gold Share Posted October 17, 2015 Ah 'ave purrrchased a leetle Frenchman ce soir, to 'elp with ze sizing of the locomotief. 'E does not know it yet, but 'e will soon be a victim of Madame Guillotine, when 'is new 'ead arrives with a turban. C'est la vie. Once her Ladyship has arisen from her post night-shift sleep, I will produce a diagram at the right scale -the one shown is 1.4x too large. 7 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 17, 2015 Author RMweb Gold Share Posted October 17, 2015 (edited) I put the name into GI and lots of pictures came up. I don't know if any are different from the excellent ones people have posted, but it's a dead easy quick look. I found: - pat patent.jpg Tony,Many thanks, that is not an image I've seen before and will be extremely valuable when building the coach. Cheers Stu Edited October 17, 2015 by Stubby47 1 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 17, 2015 Author RMweb Gold Share Posted October 17, 2015 Now we can see ze leetle Frenchman is now ze gross Frenchman.. The loco will be100mm long by 60mm wide, with a wheelbase of just 34mm Next task is to create a card mock up to assess where the motor might fit. 6 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 18, 2015 Author RMweb Gold Share Posted October 18, 2015 For the card loco mock-up, see here : http://www.rmweb.co.uk/community/index.php?/topic/103277-scratchbuild-loco-challenge-psmt-no-4/?p=2056542 Link to post Share on other sites More sharing options...
RMweb Premium Sasquatch Posted October 18, 2015 RMweb Premium Share Posted October 18, 2015 (edited) Personally I think you should be in a straight jacket Stu. That's what society would do with most people who think out side the box, so take it as a complement. Have you considered putting two reeds in the loco and magnets in the ground. Each section of track would need to be the length of the wheel base and with alternate +ve -ve. Basicly it's two rail but with the rails laid end to end, any standard controller would work. Employment of a decent flywheel would help and the magnets need to be precisely placed. Less moving parts = less to go wrong! I think It would also be easier to replace the reed switches on the loco when they weld up! Good luck what ever path you take. Edit. Forgot to mention placing two diodes either side of the motor! Edit two: Correction you need only one reed and a DPDT relay. Low blood sugar, can't think straight this morning. Edited October 18, 2015 by Sasquatch 3 Link to post Share on other sites More sharing options...
RMweb Premium Sasquatch Posted October 18, 2015 RMweb Premium Share Posted October 18, 2015 Have just looked at your loco build thread. I now see what flaw is. If there are reed switches which could be pulled on and pushed off by the polarity of the magnets it would simplify things. A simple relay with DPDT is needed This leaves two options if not. 1st a row of magnets along side each other section of rail or 2nd a mechanical two way switch in the loco like a solenoid switch operated by magnets either side of the rail. Hence my original thinking of two reed switches. To eliminate shorts perhaps an electronic flywheel built into the loco? I need to eat and get my brain working and not jump the gun in future! Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 18, 2015 Author RMweb Gold Share Posted October 18, 2015 Shaun, Thanks for those deep insights - I'll bear the straight jacket in mind. I like the idea of a flywheel, but am not sure I've got room for one, unless It can be hidden in the firebox. I can't see how your DPDT + relay + diodes is any simpler than my suggestion (too late in the day here), but will try to decipher it tomorrow. Meanwhile, have been painting 7mm oil drums (for Wheal Tiny). 1 Link to post Share on other sites More sharing options...
CourthsVeil Posted October 23, 2015 Share Posted October 23, 2015 (edited) Hi Stu,I hope you will not frown too much when I hijack your thread for a short time. In the meantime I tried my luck with the concept I presented in various former posts. I proposed the use of a relay to ensure simultaneous switching and maintaining power. Was really a steep learning curve! Went not without another amendment to my proposal – I had to learn that latching relays always need TWO pulses: one to switch, a second to switch back… Here’s the new (and final) circuit: Today I finished my test rig, made a video clip and here it is – just 15 seconds, but that’s enough. This is not the real thing (i.e. a monorail loco driven by a real prime mover), but just a manually pushed wagon with a LED that proves the constant flow of current. … https://youtu.be/th00VOto4ck Pls don’t mind the flickering – has nothing to do with the switches or the relay. It’s just due to insufficiently cleaned wheels. Me thinks this should work likewise with a real motorized loco – but a good flywheel is recommended! End of hijack… Regards Armin EDIT: to keep this intrusion short I posted a detailed explanation in my Port Chambre thread. Edited October 23, 2015 by CourthsVeil 2 Link to post Share on other sites More sharing options...
DonB Posted October 23, 2015 Share Posted October 23, 2015 Just seen Armin's post, I've also got a suggestion which I've started on the other thread, but since this thread seems to be the place for theories I'll continue it here later. Link to post Share on other sites More sharing options...
DonB Posted October 23, 2015 Share Posted October 23, 2015 Repeating my entry on the other thread,:- Hi, Stu. A late response to your problems with magnets and reed switches. I've had opportunity to discuss this problem with a qualified electronics electrician who visited us this week. He proposes a solution which dispenses with the need for magnets and reed switches, but at the expense of insulating the wheels from the chassis. (I should emphasize that he has never had any involvement with owning, building or operating a model railway!! so it took a while to explain the concept, and why anyone would want to do this! I think he may subscribe to the straight-jacket school!) He proposes that the magnets and reed switches be substituted by a diode array in the form of a couple of Wheatstone bridges, and that the alternate rail sections will always be connected, positive - negative - positive - negative etc. Now that the guests have gone, I will redraw, hopefully legibly and logically, the sketches and notes he / we made and post them here in the next few hours for your consideration. So:- We think that if the wheels can be insulated from the chassis and from each other (Insulaxles?) then the problem can be resolved by diodes connected to each wheel as shown in the sketch circuit. Effectively giving a Wheatstone bridge in each of the loco and carriage. This ensures that the positive and negative currents are "filtered" as required by the motor. The rail needs to have lengths (see later) fed alternately positive and negative, and will need to have its gaps filled with an insulating material to prevent the wheels falling into the gap and shorting out. When a wheel crosses a gap the current flow to the wheel will reverse. Most of the time there will be 2 wheels from each vehicle giving positive and negative contact from separate rail sections. But when crossing a gap we get a 3+1 situation,so to maintain reliable current flow it is necessary to limit the length of time that a 3+1 situation applies, and to have "stay alive" capacitor across the motor terminals. The next "Trick" will be to establish the rail lengths, by measuring the distances L1 and L2 , The Important thing to minimise the time when only 1 wheel is providing a current route is when L1 should equal L2. and it will help greatly if the loco and the coach wheel bases (W1 & W2) are similar. Take the average of L1 & L2 as the required rail section lengths. The insulation applied to the rail gap will need to be smoothed to match the rail profile. Connecting rods may also need to be isolated, depending on how the wheels are insulated from the chassis. He suggests that suitable Wheatstone bridges can be obtained from Maplins as small circuit blocks Hope this all makes sense. 4 Link to post Share on other sites More sharing options...
trisonic Posted October 23, 2015 Share Posted October 23, 2015 Can I just say that this thread is now longer than the real Patiala State Monorail Trainway. Best, Pete. 1 Link to post Share on other sites More sharing options...
RMweb Gold Stubby47 Posted October 23, 2015 Author RMweb Gold Share Posted October 23, 2015 Many thanks Don. I'm taking a large gamble here, but what I think you mean, instead of a Wheatstone Bridge, is a Bridge Rectifier - 4 diodes in a diamond formation. Otherwise, this looks to be a perfectly viable solution, provided the wheels van be isolated completely from each other and the chassis. It also removes any requirement for polarity switching, and is allows the train to both reverse, and travel forwards the opposite way along the track. As the chassis of neither loco or coach is yet built, this might be the solution I choose. Cheers Stu Can I just say that this thread is now longer than the real Patiala State Monorail Trainway. Best, Pete. And has more twists and turns... 2 Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted October 23, 2015 RMweb Gold Share Posted October 23, 2015 and is allows the train to both reverse, and travel forwards the opposite way along the track. The loco will only be able to go forwards if the diode bridge scheme is followed Andi Link to post Share on other sites More sharing options...
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