Junctionmad

Solid core wire is used in houses because the cable is held completely immobile by the fixings and mounting systems and there is no vibration . The large amount of cable runs and hence the cost being the deciding factor in my view it has no place on a model railway nor should solder be used as the mechanical method of attaching droppers to it. I can never understand how people spend 1000s on rolling stock and yet scrimp and scrape on what is an important part of any layout , the wiring and connector systems use a suitable tinned multi strand cable wherever possible and leave T&E for your cooker !

The issue with common return is that the potential exists for confusion where power supplies turn out to be commoned together often without the knowledge of the user furthermore the preponderance of SMPS abc the fact that some/many have earth bonding means issues can arise , linear transformer based supplies are virtually banned now anyway nobody is suggesting “ it can’t be done “ nor that it’s inherently somehow unsafe, but there are good electrical /electronics reasons why separate ground returns are a good idea, especially as more and more electronics are deployed on model railways in the general scheme of things for the average layout the advantage of slightly less wire is today a dubious benefit. Dave

I would not suggest using a Pi , pi’s are not great for direct IO as the operating system complicates everything an NX “ style “ operation is quite a simple sketch , you could forget the push /pull NX buttons used on the prototype and just use simple push buttons , each with an associated led your sketch needs to read the state of each button , when an input is triggered , which you have decided is an “Entrance “ , your sketch then flashes all the leds associated with a valid Exit route , on pressing an exit button, the relevant button entrance and exit led turns solid , all other exit leds go out . The Arduino then uses IO to switch points and signals etc. your sketch has to ensure that any conflicts are detected and the relevant exit led is not flashed ( ie that exit route isn’t offered ) , there are various ways to do that , you could maintain a table of points and their status ( free, locked to a route ) so that you can tell if the point can be assigned to a intended route ) cancelling a route could be done by simply pressing the same entrance button , ie your logic knows the button is “ locked” to an active route and hence pressing it , does a route cleardown process you may find you rapidly run out of IO, ( and you will ) , so you either have to use multiple Arduino's, which complicates the code greatly, or use some IO expanders the Arduino has more then enough power and memory for straight forward layouts a big layout will tend to result in a lot of code, but much of it repetitious in nature tables can be used to map routes and hold status ie route table ( columns , button no, pointA, pointB,PointC, exit button no) hence on detecting a button push you can scan the route table to determine the associated points , and the exit button , by finding all entries corresponding to the entrance button , you can determine all possible corresponding “ exit “ choices further tables can provide signal numbers etc , tables in RAM can be used to hold route status , points locked , free , etc not a trivial coding task , but not difficult if you have mastered the basics of Arduino programming Dave

Does someone now have a full schematic ? Dave

Personally I avoid common return as I’ve seen to many issues as a result of unintended interconnected supplies

Bearing in mind the OPs requirement , I can see the Bachmann unit as being entirely sufficient , Personally , unless you have a clear view of your future requirements and more importantly timescales and budgets , I would avoid “ expandable” systems. The Nce system mentioned in the post before , is nearly twice as expensive as the Bachmann unit. This is money wasted initially and you may never develop the need for the expansion capabilities it offers. If and when when your DCC horizons expand , you will have the experience of the basic systems under your belt , and know better what you want and can afford. Buy then for that requirement but not now Dave

My experience is that without a CDU to limit duration , it’s very easy to burn out a seep coil by holding the switch over too long , one coil may have failed Dave

Most modern switchmode supplies for various EMC reasons have 0V connected to mains earth , hence you have to be really really careful about connecting them in the manner you mention , in general it’s not a good idea.

the older classic , just uses a zener clamp to regulate the motor voltage to around 6V, ( which is why powering them from more then a volt or too more is just waste energy Hence it will have no real issue with half wave rectified DC The analog IP has a conventional regulator and micro onboard and benefits from full wave DC

classic is a simple stall motor with a internal zener clamp to allow a range of DC voltages The analog IP , has a Mico in it that shuts off current at the end of travel and better power regulation allowing a better range of inout voltages . In fact given the small difference in price , its now never worth buying the classic dave

Half wave yes , but that’s not AC

Interesting layout , I make new comment on the overall “ play” value which seems very good. Howevef i do think operator access is far too tight , there are areas with 900mm or more from edge to track , which in my view is very difficult to manage , not to mention almost impossible to work on when erected the central well is far far too restrictive imho its needs a bigger space also a 600mm min curve is far too tight these days imho

Just a small point , it’s likely you used IN4001 with a 50V peak absolute rating and it’s this spec you are exceeding due to the use of a CDU and hence a much higher voltage in the back EMF 4001 diodes actually have considerable surge capacity approaching 30A , so its very unlikely the current is the issue you need to up the voltage rating ie IN4002 or greater imho dave

As a young engineer, I joined a “ blue skies “ R&D facility of a major multi national ,” only two things will get you fired” my boss said , “ insulation tape or chocolate blocks “

Could I suggest that uninsulated copper is not a great solution. Conventional insulated wire bus and a good connector system will produce a better arrangement , solder on its own is not a good mechanical connection

If you have some interest in electronics, them the MERG cbus system is worth a look and also has its own very low cost DCC controller system. Full source code , circuit schematic etc are available so no closed proprietary system here. You need to be comfortable building simple electronics as the systems come as kits disclaimer : I am a current MERG member

Most likely a micro of some type is the part with no Id

I suggest for 00 feeds should be a minimum of 7 strands of 0.2 tinned wire I would not reccomend solid core. No issues soldering 7 strand to the bottom of an OO rail

If it never switches then just wire the frog to the correct DCC polarity , if the loco stalls you have other issues

Very unlikely a electro mechanical circuit breaker will act before the booster /command station cutout acts

I don’t think it’s possible to connect a single push button in that way. DCC concepts manuals tend to have huge amounts of text but very little technical information , but I suspect the PB inputs are logic inputs and you are essentially connecting two logic systems together I suspect you need either a double pole push button or a use a DPDT relay driven by the PB but each pole is connected to the respective cobalt

What I’ve seen is most Xt60 connectors are rated for 30A continuous and 60A pulse , voltage should be good for most common low voltages ie < 50v , all greater then dcc requirements

With connectors , doubling the voltage doesn’t half the current , the current is a function of square area of the contact and the voltage rating is a combination of insulation , protection and creepage

It should be pointed out, if you derive a power source from the DCC rails and rectify it , you get a “ local gnd “ that is not generally compatible with other Gnds on the layout. Ie , deriving a supply from the dcc track to power a few platform lights is entirely practical and you don’t really mind the lights going off on a track short circuit but where you might be interconnecting grounds ( or OV) you need to be careful you know what you are doing Dave

You don’t need a big capacitor because the frequency is high and it’s a square wave in fact you don’t need one at all really