retroaudio Posted March 28, 2012 Author Share Posted March 28, 2012 What you need is a very small fusion reactor within the loco, with a small steam turbine and generator. You will also need a voltage sensing relay to monitor the track voltage. When the voltage falls, the relay drops out and switches the motor power source from the track to the generator, then back to the track once power is restored. So that's the answer! And I thought I could could get away with a flux capacitor stuffed into the back of a Delorean! Some very interesting replies here with much food for thought. Paul Harman's DIY decoders look interesting though. Link to post Share on other sites More sharing options...
Baby Deltic Posted March 28, 2012 Share Posted March 28, 2012 Hmmm... 　 I've been think about this thread and Suzies suggestion of using a DCC Decoder. 　 I can see this as a possible solution. So much so, that I might enter it in the 2012 "Inovation Challenge" - If Suzie and RetroAudio don't mind, that is, and I find a time machine so that I can actually 'make time' to work on the project! 　 Making your 'own' Decoder is really a none starter. It would cost too much, never work, be bigger than your fist, and would look like a birds nest at the end of it - and that's the 00 version! 　 BUT... How about modifying a commercially available Decoder? 　 Advantages:- Cost - Much cheaper than you can even buy the bits for seperately. Proven design - lots already running around. Small - There already small enough to fit into a Loco (minus the energy storage)! 　 Disadvantages:- Cost - Expensive. Risk - you might end up 'wasting' a Decoder or two and all your time! Time - Developing the software. No drawings - you would have to "reverse engineer" the Donor Decoder. Needs to work with different types of DC controller. 　 Prerequisites:- The Decoder needs to be big enough for me to see it! I would need a 'Donor' Decoder to be based of a Pic-Micro that I could use. The "relevent bits" would need to be accessable. 　 Feel free to add more... 　 Features:- DC operation from 3.5 - 4.0volts to, well alot, say in the 12 - 18volt range. (Every controller is different! And some would still be incompatible, but 'Relco' type units would definately be a no no.) Selectable "Stay alive" options - say:- Selectable power output when a power break is encountered (variable limp), Initial Boost (or jump) into the dead section, Brain power priority (sod the motor), economy mode (use what you can according to whats left in the storage capacitors), err any more suggestions? Say a battery option (much better than capacitors but adds another level of control problems/choices). 　 This would, primarily, be a software project wit0h some experimenting and tweeking once it was working but reverse engineering the Decoder would also be time consuming. 　 Just a thought... 　 Kev. (Hmmm... but not a simple diode and capacitor solution, as initially required, plus the DCC decoders were a cost issue to begin with...) 　 Never lose sight of the original goal! I think the problem would be that the original PIC might have had the 'code protection' bit set during programming, which will blow fusable links and prevent access to the program memory to read or alter the program. So you will need to desolder an SMD chip and fit a new one, plus make an interface to allow in circuit programming. You would also need to be able to decode the DCC to command the chip when the loco is on the track. Maybe a good knowledge of the DCC protocol would be useful for this. Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted March 29, 2012 RMweb Gold Share Posted March 29, 2012 Reading the existing PIC was never really in my thoughts anyway. Disassembling somebody elses programming just drives you mad! But it could be useful just to read the first bit of code - ie the bit that configures the PIC - and that would be easy to disassemble as it would be simple in-line code. Adding the wire links to allow programming would also not be an issue. One of the ladies at work, on the assembly line, can weald a soldering iron like a surgeon! Much better than me and i'm supposed to be a pro! (Removing and replacing the PIC would also be done by her!) The DCC protocol is documented, and available, on the web. And, if all else fails, you can put a scope onto the output of the DCC controller. (Disconnect it from the railway first as all the noise you see when DCC is in use is astonishing. It's a wonder it works at all!) incidentally, PICs don't have "fusable links". They have memorycells driving FETs. These are covered by wide plates of track metal - mad of alluminium on the actual silicon die - to prevent UV light from erasing the protection bits. I've seen websites that instruct you on how to mill the top off the PIC, Mask the main memory (to protect it from the UV light coming next), and to angle the UV light so that it goes under the protection bit memory masks. I've seen other websites where this is a full service to you plus they will disassemble and document the code, reverse engineer the PCB and provide schematics AND, at the end of it, give you a price and delivery date if you want them to make the fully reverse engineered boards! Guess which county these services are offered in? Kev. Link to post Share on other sites More sharing options...
Baby Deltic Posted March 31, 2012 Share Posted March 31, 2012 Reading the existing PIC was never really in my thoughts anyway. I've seen other websites where this is a full service to you plus they will disassemble and document the code, reverse engineer the PCB and provide schematics AND, at the end of it, give you a price and delivery date if you want them to make the fully reverse engineered boards! Guess which county these services are offered in? Kev. China? Russia also reverse engineered a lot of the western CPU's such as the 8085 and Z80 back in the day. Link to post Share on other sites More sharing options...
Grovenor Posted April 1, 2012 Share Posted April 1, 2012 Making your 'own' Decoder is really a none starter.It would cost too much, never work, be bigger than your fist, and would look like a birds nest at the end of it - and that's the 00 version! 　 Complete design available here, (look for loco decoder down the page) parts will cost in the region of £10. We have built quite a lot of them, they do work, fit into locos and have no resemblance to a birds nest. Regards Keith Link to post Share on other sites More sharing options...
Allegheny1600 Posted April 1, 2012 Share Posted April 1, 2012 A fascinating thread here and something I've been contemplating for awhile now! In the original OP, I thought the concept was valid. Bearing in mind, I am the worst kind of electrical numpty - in that I understand a little bit about electronics but not enough! However, surely the point of a "stay alive" system is that it does only require tenths of a second thereby allowing the loco to reach a point at which it can gain track power again? What would happen though where for instance, a class 08 is shunting over intricate (clean, live frog!) pointwork at say, 5 volts and contact were lost with the track? With plain DC obviously, the loco would stall! With a "Stay alive" system, wouldn't the loco have just enough juice to carry on until contact were re-established? Or, because the loco has been running at 5 volts - would the capacitor simply not be charged up enough for this? Thanks for any help here, chaps! John E. Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted April 1, 2012 RMweb Gold Share Posted April 1, 2012 Complete design available here, (look for loco decoder down the page) parts will cost in the region of £10. We have built quite a lot of them, they do work, fit into locos and have no resemblance to a birds nest. Regards Keith Hi Keith, Thanks for the Link, I'm looking at the MERG site right now! I really should join, but i never seem to get around to it. (Took me years to join this site! And I really Really should have joined the 'Dreadful' site when that was going.) My comments were "aimed" more at the ... er... how should I say this, erm... the less knowledgeable of electronics members.... and not at the people who clearly do know the difference between a Thyrister and a SCR! ;-) I've just had a quick look at "Decod13 Rev C". I might even 'borrow' the 33k values! Not sure when I can give them back though!) The feedback circuit, (R26, R27, & C2), clearly benifits from not having to pass, (or dissopate), the Motor Current. Thus saving a LOT of PCB space but I was wondering about the lack of 'over voltage protection' to the PIC. Clearly, this is not a problem as, (as indicated), there is not a problem with this in the field. (Possibly only a problem if one of the lower H-Bridge FETs fail oc or, more likely, a lead falls off the Motor. Still, not much current will get through to the PIC but still... As for the "birds nest" reference, very few 'muggles' would attempt a home brew design with surface mount components. (Is muggles now an OK term to use here? If not sorry in advance.) I certainly won't use surface mount - willingly that is - as I can't see the damned things! Kev. Link to post Share on other sites More sharing options...
RMweb Gold SHMD Posted April 1, 2012 RMweb Gold Share Posted April 1, 2012 Bearing in mind, I am the worst kind of electrical numpty - in that I understand a little bit about electronics but not enough! A 'little knowledge' is dangerous - you would not believe how dangerous I am. ;-) 　 However, surely the point of a "stay alive" system is that it does only require tenths of a second thereby allowing the loco to reach a point at which it can gain track power again? There are several different methologies available in 'how best to use the stored power in a power cut'. You could just directly connect the stored energy to the Power circuit to give it straight away to the motor. You could decide to ration the stored energy. You could workout what the frictional forces are and attempt to compensate. You could come up with something brilliant. But i can pretty much guarrantee that you're not going to come up with a version of 'perpetual motion'. Each methology has its good, and bad, points. It's best to let the end user decide plus giving them something to tweek as well. Still, the worst we should be looking at is some badly layed track, (convex and concave track with large fixed chassis), and dead frogs. (The design should also be able to cope with running into 'live frog points' set against them giving, not just a short, but the wrong polarity! 　 However, surely the point of a "stay alive" system is that it does only require tenths of a second thereby allowing the loco to reach a point at which it can gain track power again? What would happen though where for instance, a class 08 is shunting over intricate (clean, live frog!) pointwork at say, 5 volts and contact were lost with the track? With plain DC obviously, the loco would stall! With a "Stay alive" system, wouldn't the loco have just enough juice to carry on until contact were re-established? Or, because the loco has been running at 5 volts - would the capacitor simply not be charged up enough for this? John E. Speed of the train also has stored energy. The slower, the train, the more energy you will need to draw from the capacitor to compensate for the train not having its own momentum. (We all know to drive faster over that bit of dodgy track!) Again, DC control has many Many different types of basic operation/control/track voltage/current control/modulation/etcetera. DCC has only one - in power terms that is, and each will affect the storage charging ability, and thus consequent enrgy stored. The Energy density of caps - even button cells - is rubbish. Similarly, the energy desity of batteries is rubbish compared to petrol. Kev. 　 Link to post Share on other sites More sharing options...
Suzie Posted April 1, 2012 Share Posted April 1, 2012 The MERG decoder is likely to give the best performance, but it will be a bit big if you make it using full sized components. The DCCDIY decoder is designed to be made with standard sized components on stripboard only five strips wide (0.5") so might make a better starting point, and uses an analogue comparator for input to give better performance on measuring track voltage. If you are making a dedicated DC unit, take the DCCDIY hardware design and either write your own firmware from scratch (should be quite easy for DC only operation using a PIC 12F675), or port the MERG firmware. Dont forget to add the extra capacitor. If you want to take a commercial decoder as a base, some of the TCS decoders use a 16F630 PIC which it should be possible to reprogram new firmware into it, with only minor surgery required to add an in circuit programming connection. Link to post Share on other sites More sharing options...
retroaudio Posted April 2, 2012 Author Share Posted April 2, 2012 Suzie, I think I will try a DCCDIY just as a little project and at least it will give me an insight into what DCC is all about. I have a few locos not DCC ready to experiment on As I purchase more new locos which are DCC ready, long term DCC may be the way to go. Thanks, Richard. Link to post Share on other sites More sharing options...
Petri Sallinen Posted November 1, 2012 Share Posted November 1, 2012 Many years ago I saw and had a go at a mechanical stay alive system at York expo. This consisted of the motor driving through a clutch to a big fly wheel you needed to reverse power to stop quickly. This system based on centrifugal clutches that is typically used with massive flywheel. If I remember right I saw this first time in Imrex exhibition in the beginning of 1990´s. The system is made by Swedish Brimalm Engineering and I think they tried to sell that also in UK under the brand name of Dynadrive. I think they are still making this system and we have used that in some Finnish models. I have to say that this works pretty well, but there have to be enough space inside the locomotive body for components. http://www.brimalm.com/en/current/brimalm-components/centrifugal-clutches Here you are able to see how we have used this system. Petri Helsinki, Finland Link to post Share on other sites More sharing options...
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