Junctionmad

IPA simply isnt strong enough in my opinion, Lacquer thinners is better .

As a test , I picked up a few lengths of C&L HiNi track and did some resistance tests with my bench DVM. Even accepting what you say , Id suggest that the practicality of extracting tiny differences in voltage drop against a noise floor typical of model railways is close to impractical. This is before you add effects that occur when track is painted and ballasted as you get leakage currents and parasitic currents flowing. My DVM tests suggest that there is a small range of resistivity in practice and that this range overlaps the absolute resistivity from track section to track section , meaning that you could even have to resort to track resistivity profiling to get it any near working

The phone is connecting to the router how do you know that

1.25m SMD pitch isnt at all difficult to hand solder

The typical way is to drive the C& D inputs from a micro controller output , the motor direction being controlled by which one is high or low there is no need for any DPDT logic ? The SN driver while rated for 1A ( in theory ) is, short of massive heatsinks ( which are impractical with dip chips ) unable to get anywhere near 1A continuous without frying. My comment re L298 is not “ derating “ you must take into account the junction to heatsink calculations to determine the chip die temperature rise. This sets the operating point of the device and hence the current capability, De-rating would then occur from that point for example to handle an increase in ambient temp range typically Furthermore the worst case DC operating point , for this chip is an absolute maximum of 2A. No designer would operate at that point , a spike would kill the device , equally the thermal resistance of the device to the case is 3degrees/W and as it’s bipolar the source and sink saturation voltage at 2A is nearly 3 volts. , ie 6V across the full bridge. Using a big heatsink might get you a combined figure of say 6-8 degrees /watt , so you could see 12 watts of heat in the chip , this would cause 96 degrees of rise above ambient , not nice. For both sets of drivers this would fry the chip rapidly. Hence given modest heatsinks and saying inside a reasonable operating envelope, about 1A is practical with this chip. Mosfet H bridge drivers with their dramatically lower Rds on resistance are capable of much higher power.

The C and D pins are the PWM drive inputs to the H bridge. In the case of the example the motor is being run at full speed. For speed control the mark space of the PWM controls the speed . Ven is the “ enable” control typically tied high for PWM applications . It does not control direction pin 15 is the current out of the bridge , when a voltage is developed across a small resistor , this voltage represents the load current and can be input into a micro controller to determine when to shut the PWM drive to avoid over loading the driver chip diodes D1 to D4 are flyback diodes to prevent the collapsing field of the motor on shutdown or reverse from killing the driver chip , the 298 is quite sensitive in this regard

Several things. Firstly the SN74410 is a very old and nasty chip ( I know I use them on my own CBUS designs ) , you’ll get nothing like 1A out of them as they will fry. The are not short circuit protected or protected adaquately from over temp. They are very inefficient too, consuming considerable power themselves ( due to high internal resistance ) which all appears as heat. Mine get noticeably warm when drawing 100mA The L298 dual bridge is a better bet , again it’s not well protected , so you need to have active current detection , so that you shut down the chip in times. They are good for around 1A with some hestsinking. much easier in my opinion is to move away from PICs and into the Arduino environment you can get any number of motor driver shields and there are associated software libraries and examples to help you develop solutions. With PiCs there aren’t good development tools available cheaply , whereas the Arduino environment has stacks available for free Note you don’t need DPDT switching if you have proper full bridge drivers , nor do you need a low ( voltage or current ? ) startup , everything can be done by adjusting the mark space ratio of the PWM signal. you will need to generate two voltages , the logic supply and the track supply, these can be derived from one supply voltage. Be be careful with common return , so that you appreciate the issues I suggest you join MERG , where you can piggy back on various very similar projects, which might enable you to get up the learning curve faster, especially if you haven’t much experience of electronics or embedded software Dave

Mega points have modules that drive stall motors , solenoids and yes servos. , they have long moved on from servos only

Really, on a big complex layout , you need a separate layout control bus , preferably bi directional . So you cam feed back point blade position and or track section occupancy. MERG CBUS would be ideal , if you are prepared to do some simple soldering. It’s also the cheapest system around and there are modules to drive stall motors , solonoids etc. hence a mimic panel /switches etc can be easily build up at minimal cost. You could also integrate virtual mimic panels via JMRI ( disclusure , I am a MERG member , ,I am also responsible for a big O gauge layout ,55 cobalts , 20 semaphores , 25 ground discs , track section occupancy, DCC for traction only , Z21 ) ps another system worth looking at is the Megapoints system. But it’s not connectable to DCC

To be fair I didn’t spell them out , simply to see what level of research has been done. If you are interested in signal controlled layouts where the progress of the train is controlled by signals , then these are a good read as they provide solutions ( analog like super bloc ) to typically what you want to do. I know the archive documents are on the Merg site , but I think they are around elsewhere. LSC and RLSC ( which followed ) don’t have any speed control aspect however , merely a means of linking the dc controller section by section the issues with all these systems is that conceptually the idea is simple, but the implementation on a “ real “ model railway can get complex very fast, especially where a comprehensive solution is desired ( as in the throat of a complex signal controlled station approach, for example ) ive seen two super bloc layouts , lots of work etc.

RFID is complicated in model railways by two factors , (a) the need to be inexpensive and (b) the whole issue of space constraints. unfortunately the physics don’t scale down by 1:78 ! , it’s further complicated by the lack of dedicated tags and readers , we have to roll our own. For example constraining the reader to not detect adjacent trains on a OO track isn’t easy , equally , ensuring reliable read rates at speed , can be tricky. And you still have the issue of the “ back end systems “ that receive the train ID and logically associate the info with other parameters. As to your second point there is no connection per se, between railcom and dcc , the information from a railcom decoder arrives in exactly the same way as the rfid , ie a number , the back end is essentially the same from that point on. The system IS completely separate ( doc traction & railcom ) other then both use the same dcc ID The advantage of railcom is that there are off the shelf modules , ie Digijeiks etc. These convert the railcom data into loconet and this can be fed to jmri or used by other computers connected into the locomotive bus. The alternative, rfid , is almost complete roll your own , from sourcing readers and tags to developing reader electronics and a method of getting the data to something ( via canbus , i2C or something similar )

I have no idea of the technical capabilities you have both in electronics and embedded software development. But the task you are considering is fairly big . You should look at RLSC and LSC methodologies as well.

Which is of course made in China

One hopes he has similar budgets for his model railway project plus a well paid engineering team.

You have mentioned this before Andy. It’s issues are the problems of real world applications , the resistivity of track varies, from section to section , the round trip resistance includes the motor which again is again variable , the noise floor is high compared to the measured quantity. so the theory is sound , but so is controlled fusion:D

RFID on real railways has simply no comparison with rfid on a model railways , everything is different , from budgets , antennas , distance , space etc. But hey knock yourself out. We are all interested in seeing someone crack the solution comprehensively It’s equivalent to saying Diesel engines would be good as OO traction because they work in full size railways. there always seems to be a lot of confusion around over Railcom Railcom uses a “ slot “ of time in the middle of the dcc signal to send back information other then that it has nothing to do with dcc traction control and the signalling system which can be controlled by any means ( layout busses , jmri , switches and buttons ) etc.

There are several mind melds that users need to accomplish to use templot. The first is to discard any any notion that this is a derivative of any form of “ settrack “ planning application. A comparison would be Autocad versus openOffice Draw. The second is the interface “ looks” like Windows, but in fact , it’s completely idiosyncratic in nature. Hence you need to largely discard your “ expectations “ even the common dialogs arnt present I always say with templot , lay the track then modify to add turnouts etc. Do not view turnouts as a seperate piece once you achieve mind meld status you’ll be fine templot is by by no means unique here , try getting to grips with Fusion360 for anything other then trivial stuff and you’ll face similar learning curves.

The VMS catalogue is available online , includes subsidiary options , helpful major dimensions Etc http://www.vmstech.co.uk/downloads/VMS_Rail_Catalogue_IssueJ.pdf

Mention is made of RFID. In my opinion having reviewed all the work done in MERG, is it’s not ready for “ prime time “ ive used Railcom , there are a couple of issues in that many dcc accessories don’t work correctly with it. the other issue is multiple Railcom encoders in one track section is only resolved for those locos receiving active dcc addressing the issue of combing IDs for multiple units , etc. Is not resolved with Railcom either and would have to be resolved in external software it is however abut the only system that’s mission capable

Not to start another flame session , but, Templot , has a very “ unique “ user interface and logic structure . Today GUI users expect very similar look and feels from “ drawing “ ( as a generic term ) packages , typically objects are fully manipulated by mouse movement , select and group select tend to follow conventions and object snap etc exists. All this functionality ( and much more ) exists in Templot, as it’s an extremely versatile application. But you have adapt to the very different underlying logic and user interface. This means that (a) the learning curve is quite steep and (b) it’s not software you can just “ pick up and go “ its further exacerbated by the fact that templot requires a degree of understanding of prototype trackwork , an area where many railway modellers have a limited understanding ( rather like signalling ) , even amongst those modellers that build track. Having said that, Templot is a fantastic resource and you will benefit by progressing up the learning curve and Templot Club is a fantastic resource to aid you in your understanding dave

We have used woodland scenic Ballast , on 6mm cork ( O gauge ) extensively , once glued with dilute pva it’s extremely noisy. The next track laying will use two layers of closed cell foam one forming the ballast shoulder , the other to isolate the ballast from the baseboard

I actually cannot understand in this day and age with the computer tools available, why anyone wouldn’t plan out in detail in advance a complete layout. Confirm minimum radii , point position , space for point motors and then design the baseboard etc. All before touching a piece of real track. there are several track design applications that will do this for you for the Mac you have RailModdellerPro which is excellent why anyone buys track to plan or uses paper templates is beyond me at this stage

Im trying to understand what the GWR used in later years for electric platform lamps and has anyone a picture of a typical lamp and are there are 7mm suppliers thanks Dave

This is a forum. If the OP wants to debate any aspects he or she merely has to post. in that absence , it’s just a discussion

AndyID , Your last set of posts are close to trolling. You come across as arguing against the poster and not the topic , yet you contribute nothing to the subject I’m a professional EE and a MR for 30 years. I’ve seen an awful lot of layouts in that time and worked on many loco identification is a difficult task. RFID has problems , barcodes don’t work , magnet systems are very limiting . I’ve yet to see a good solution for dc then you have to tie speed profiling in again . MERG over the last 40 years probably contains the greatest number of expert contributors and almost every aspect of layout and loco control has been investigated and various solutions developed nobody there ( MERG ) has solved the issue there either , there are partial solutions, and some are quite complex yes my views ate subjective but they are backed by a lot of experience in both the technology and model railways. it’s not always possible to engage in a long technical discussion about certain aspects to show what’s difficult . But if the OP wants I can do so outside of that all i can do is express my personal perspective