I am confused. My understanding is that AC is on the track and the AC is modified by the base station to pass info to the decoders, but if you measure track power, it is AC. Are saying that I should put 12v DC into the track and it is modified by the base station to AC or does it stay DC jonnno
You must input 12v to 18V DC into the driver board. The driver board then turns this into a polarity switching supply for the track. The speed of polarity switching fluctuates - and it is this fluctuating that carries the data for the loco decoders. The voltage on the track is switching rapidly from +12V (for example) to -12V. A true AC supply (unlike DCC) is a sine wave supply. DCC however is a square wave supply (on the track). A normal test meter will show a reading on its AC setting but it will not be an accurate voltage reading because it is calibrated for a sinusoidal (sine wave) input. Jim
no the DCC signal is PURE DC Pulse width modulated signal(PWM) the is NO negative voltage anywhere on the track, the signal is ALWAYS 0 to +12 (or higher if your input DC is higher) only in the decoder does this get reversed for the motor and even then it's still only a pulse (at full voltage, the amount of pulses determines the speed the motor turns, this is also why you can't replace motors with a lower voltage one, as it will burn out)
That may be true for traditional DCC (I don't know)*, but as I understand it with the L298 full bridge driver circuit as wired on the DCC++ system, neither side of the track is connected to 'earth' (0v). Each rail is alternatively switched to +12v (and the other 0v) then it is reversed so that the other rail goes to +12v (and 0V), the net result is a 24v P-P swing centred around 0v. Gregg explains it starting from here: * Edit: in fact looking at Greggs video again, he confirms that it is a reversing (bi-polar) supply as there is always a voltage between the rails. - (there is never a 0V difference between them) Jim
Thank you one and all. My saga continues I have now used 12v DC into the shield and the 4 red LED's light up at the base of the output sockets when I switch the power on ,on the controller. I can detect something happening on the output pins of the programming track and can see a difference when "POWER" is pressed on the controller. Is ther any other way of testing the shield for damage?
Do the LEDs switch on and off when you turn the track power on and off using software (EG controller)? If they do, I think there is probably a good chance you are ok. With the power turned on to the tracks, you could perhaps try BRIEFLY shorting out the track (No longer than about one second), and seeing if the LEDs turn off, and you should also see a power overload error at the top of the controller window. You should then be able to turn the track back on in the controller. - remove the short first though! If that all appears to work, then I guess you put a loco on the track and trying it.....
Hi Jonnno, welcome aboard. I note your comment about eventually going wifi/battery. I've done some work with this, documented here. In essence I used an esp8266 wifi board which did everything needed on the loco, and could receive JMRI commands as if it was a DCC++ base station. I ran out of puff trying to do a java chat server for the JMRI => WiDCC++ connections. I'll get back to it, but am living overseas for 6 months which meant I had to pack my test rig away.
Well, Thank you everyone but my saga continues and i cant get a train to run I have connected the base station to the controller software but did not have a train with decoder. So bought a decoder (TCS M1) and installed it. Did not work. So, is it my wiring of the decoder or the DCC++ setup? Bought a loco with decoder already installed. Does not work. So, changed the motor shield. No different If I short out the rails, the base station immediately shuts down and error message appears on the controller screen currently, when i enter the controller programming track I cant get the "programming switch" at the top of the screen to light up as in the video. I only have the programming track output connected to the rails, not the main track power. I cant communicate with the new loco at all and I am presuming that it functions properly How do I change the cab number in the controller software if I eventually do get everything working?
Hello jonnno, It looks like you are getting closer Shorting out the rails and then shutting down is the right behavior which tells me the base station does power up the track and monitors current. By any chance does the loco with the factory installed decoder have sound? Generally when a loco powers up on either the operations or programming track it make some engine sounds. Just another way to confirm everything is working okay. When I bring up the DCC++ controller app and have a loco on the programming track I click Power and then press "p" to bring up the programming track pop up box. If I click on READ engine addresses the loco generally moves forward a little and the screen updates with the short address, long address and active state. Since most decoders have a default short address of 3 I would think you should see this as the short address. Either way remember the two numbers and which state is active - long or short. If I then place the loco on the operations track and click power everything should power up fine, of course. I then go over to the list of cabs in blue on the left side. All you do is hover your mouse over one and LEFT click and it will turn a lighter shade of blue and is active. Then RIGHT click while in the box and the color should change to white with the cab number displayed. Then LEFT click again while in the box and you should see a vertical flashing cursor. Press backspace to delete the old number and then type in the new number. 3 may be a good choice for a new decoder with a short address active. Press enter to save it for this session. You should see the new loco number for the cab in light blue, meaning it's the selected loco. At that point moving the speed slide up or down should start the loco moving. Good luck!
Thank you. I am farther ahead not not completely is the problem solved using my new factory fitted decoder loco in programming track screen, "read" engine address does return 3. When I write this short address to the engine, i get success messages on screen and indeed the loco does move forward a little. Hooray I have followed the instructions on how to change the cabs and everything seems to work as you suggest so that I end up with 3 as the cab number. The speed slider does not have any effect on the loco however. I have used 3 as the cab address (is this correct or should the cab address be different from the engine address?) in 2 other cab addresses but they do not work either. I would see this as a connection issue with a fault in the connection of the controller to the base station and to the loco. In short, it probably relates to something I am doing wrong or am missing a step somewhere. I dont think i am far away! questions 1 Is it necessary for the "programming Track" heading in the programming box to light up or was that just something to do with Gregg's particular layout? 2 I am only connected to the programming track. I presume the throttle should still work, but should I try it on the main track output? 3 my self installed loco decoder does not yet work. Should I wait to get this current problem sorted out or commit suicide right now? 4 I think moving on to JRMI is what I will do, but it makes sense to me to get this sorted out and running first before taking on new complexities. Do you agree or would moving on now be a better idea? 5 Should I be doing anything with the CVs to help this problem. At present the cv values are blank. Is this my problem? 6 Can I ask where you all got this knowledge? Was it trial and error or is it written down somewhere? once again, many thanks. I hope that others who have had problems can read all this and realise they are not alone but can work there way through all of this, My problems seem to be my inexperience and trying to learn a lot of new stuff in a short time. I am happy to make mistakes. All of your imputs, however, mean that I can fix it and after all, this how we all learn jonnno
Hello jonnno, I think all you need to do is move the loco from the programming track to the main operations track. The programming track is only for programming - period. Running the loco is done on the operations track. So you would not expect the slider to work when on the programming track. I would definitely wait to tackle the self installed decoder JMRI is a very good environment and has very good support with lots of features. The DCC++ Controller app is good but it was made for a specific layout and likely will not be supported. Where did I get my knowledge? I'm simply an enthusiastic amateur like many folks in this hobby Good luck!
correct. I wired up the main track and my loco works. However, it does not run fast enough. Is this a function of CVs I have not yet looked at or is it a function of only 12v input. I might add that the loco pulls a 6 coach passenger train with ease and the speed does not seem to change whether the coaches are attached or not. I currently have it pushing the 6 carriages backwards at a constant speed which is difficult to see unless you go away and come back. Overall very happy, but need to deal with the speed issue Is there an easy way to test decoder wiring/function on my self wired decoder john
Hello jonnno, That's really good news! My experience is the same. I started with a 12 VDC supply and the trains just didn't run as fast as I would like. I had a 14 VDC supply laying around and now I have all the speed I need and then some There are two watch outs: if you go above 12 VDC then make sure to cut the Vin trace as shown in the video and documentation. Second the max voltage is 18 VDC or so if I remember correctly. Honestly given my experience I can't see why you'd need that much but YMMV I don't have a lot of experience with troubleshooting decoders but I'm sure other folks here do. Good luck!
