Is there any need to add a fuse in-line between power supplies for Aruduino Mega and another for Motor Shield. I will be using a 14V 4A supply for the motor shield and a 9V 2A supply for the Mega. If so, what value? Maybe 1A fuse for Mega and 2A fuse for motor shield? I will most likely only have 3 locos on the layout at one time but only two used for switching...
If you are talking about between the 110 to 9V and 110 to 14 power supplies and the Mega and the motorshield I've never seen anyone do that. Just make sure the wiring between the 14V power supply and the motorshield is good for 4 amps. I don't have anything now between the motorshield and the track as I believe that the command station, DCC++EX will cut the power on a short at anything over 1.7?? to 2 amps. When I connect the command station to Tam Valley boosters later that will cut the power on a short or the TV circuit breakers will if I use them to have a couple power districts past a booster. Sumner
my whole layout is on 12 volts 12 amps system will draw what it needs and i have lots of extra power for other things in the future (maybe)
My question was adding a fuse between power supply ---> Mega and power supply ---> motor shield. A newbie idea to protect components. Sounds like the fuses are not necessary. I plan to use two 6 inch pieces (1 white, 1 red) of 16 gauge wire between the PS connector and motor shield. The wire should be more than sufficient size for 4A.
Oh yes that is plenty big for 4 amps over such a short distance. You will be fine, you could use 18 or even 20 over such a short distance with only 4 amps but I like the 16 as it is just a little more physically robust. Sumner
As @Sumner states, the motor shield has very good short protection having run into a point or 2 prior to getting the TAM booster, and if your main supply in rated less than a few amps, one is pretty safe. Adding extra precaution is usually never a bad idea. Wouldn't see any need to fuse the Mega assuming you cut the Vin etch on the shield. Presumably you have done that if you are using higher than 12V for the shield VDC in. For what it is worth, there are no fuses used in any of my 3 DCC EX setups. Can you fit 16g into your shield? None of the larger than 18g solid or 18g tip tinned stranded wire I had fit into any of the 3 standard shields; Arduino, Deek Robot or DIY brands. The DCC EX group has a great gauge chart. Link below... https://dcc-ex.com/reference/wire-gauge.html One of the best things I've bought is the TAM Valley booster which is placed between the shield and the rails. Have a small layout 2x4 but it also has added benefits.. Significantly better loco performance, especially when running multiple locos, at least in my case. -With a larger power supply and TAM Valley booster, its 3A continuous and 5A peak as compared to the Arduino shield of about 1.4 continuous and 2A peak. -If your plan is to use track connected accessory decoders to control turnouts or other things, without isolating the rails from the shield, can cause stationary decoders to be unhappy if a track short occurs. -Tested placing a short across the rails and the shield didn't even flinch.
Mark Ricci Thanks for this info. i think im gunna look into the Tam Valley booster. Sounds like it would help me on my layout.
What I'm also doing besides using their boosters is I'm running two of their circuit breakers behind each one I have. That will let me have more power districts and hopefully make it easier to find a short if I have one. They have an LED on them, green when no short and turns red with a short and you can have another remote LED that is easier to see. You also have the option of setting them for a current cutoff limit of 2 amps or 4 amps. Since I'm N I'll try the 2 amp setting. At less than $35 apiece I think they are worth it. The booster used alone will also act as a circuit breaker so if you only want one power district it will do the trick. It has a higher amp cutoff but think that it happens so quickly that it isn't a problem with ones equipment. Mark are you N scale? Sounds like the booster alone has worked fine for you. Sumner
Mark, I'm still on the fence and have not yet ordered any components. I'm still early in the learning curve and trying to estimate conversion costs from a DC-based to DCC (system + decoders + misc). You made a statement I found disturbing. You have a 2' x 4' layout and observed improved locomotive performance by adding a TAM Valley booster between the control station and the tracks. All the commercial entry-level systems can run a few trains with just one power supply yet DCC++EX needs four power supplies (one each for mega, motor shield, booster, and laptop). I'm not liking the idea of all the clutter and cords with DCC++EX...
No need for concern... I like to always have ample headroom when dealing with power but estimate when running my 3 DCC (2 with sound) N scale locos at same time, 2A is lean based on the estimate of non-sound about 250ma and sound around an amp. Atlas support indicated 1 A is good for the LokSound based decoder loco's. As you know most manufacturers rate their entry level systems lean and mean. Once placing a stationary decoder(s) connected to the rails or base station output for turnout control or other accessories, at least 1 TAM Valley booster is highly suggested for isolating the rails from the base for clean stationary decoder operation. eg. A turnout is not closed and a loco runs into the point causing a short. How a stationary decoder responds can vary. A variety of unwanted outcomes can occur if the accessory decoder encounters this issue. I prefer to be safe and know that if I forget to throw or close and a short occurs, the stationary decoders should remain operational and unaffected. Especially important when I'm like air traffic control running 3 locos on a 2x4 layout. While using a Raspberry Pi 4 2G, I'd still be using 1 power supply brick if just running with Arduino. Probably contrary to what other would recommend. Have ONE female barrel connected on side of layout frame in which a 12 VDC @ 5A brick power supply plugs into. (Ledmo power supply recommended by DCC EX group in Dec2020) A barrier strip takes that and feeds to 3 devices; the motor shield, a Buck converter with USB C connector(much cleaner) for the Pi and the TAM Valley booster. If it was not for the Pi, would use a 9V buck for the Arduino. If you cut the Vin trace on the shield as is recommended, the 9V is only powering the Arduino and motor shield's controller logic(think logic draw is estimated at about 20mA). All lighting; including the Woodland Scenic's Depot, 9 LEDs and 2 dock lamps draw about 1.2 mA with resistors connected to the Pi's 5 V Vcc and GND GPIO connectors - all lighting is powered by the Pi so no additional supply is necessary for lighting. It can be easily connected to one of the Arduino or Shields 5 V pins if a Pi was not used. Plan to eventually add stationary decoders for lighting. The layout is designed to be put on any flat surface, plugged in, put loco on track and run. It is panel free with only 5 mechanical switches hidden by structures; 1 4PDT On-Off-On switch for Ops and Programming and 4 momentary push buttons for DS 64 emergency turnout control. After a 5 year decluttering period, I swore an oath when returning to the hobby to minimize clutter.
Interesting, thanks for the detailed reply! My locomotives are HO and perform very well on a DC layout with a 7 VA power supply (approx 0.4 amp). That is one locomotive operation, short trains, level trackbed. I don't know how current consumption would change with motor-only DCC decoders or with motor + sound decoders. On other forums, fellow MR'ers would say it's variable, must measure. Okay, yes makes sense to measure, but someone must have general guidelines for power supplies for HO railroads... Then the next question is can the DCC++EX handle three locomotives with sound or do I need to plan on starting out with power districts? A switch to DCC is more complicated than people make it out to be, especially for a beginner... I don't feel like I have the information to make informed decisions for the switch...
Been using NCE's knowledgebase as guide, for HO, approx 1/2 A per loco without sound... As mentioned earlier, add to it any DCC decoders that run off track. DCC can run all 3 locos simultaneously anywhere on the track with no power districts like impossible under DC. Words can't describe the joy the first time running all loco's at the same time at different speeds on small layout. Yes, the power consumed by a variety of different locos, decoders, eg will be different. Believe 1A is a good range for sound. In DC, the throttle varies the rail voltage which changes motor speed. Without districts, the loco's all move or not, in same direction and at relatively the same speed.. The voltage across the rails is constant in DCC. The decoder inside each loco reads what the throttle speed setting and using the track voltage, IT controls the motor speed and direction. This is how locos under DCC can be run individually and at different speeds and or direction, even around a simple oval with 1 power feed from the base. Without seeing your layout plan and knowing what else you will be running off the rails, its hard to say however, I ran all 3 loco's (2 Sound and 1 w/o) before adding the booster - they ran. The booster's added power is a plus as the locos do run better. The primary reason for its inclusion is as mentioned b4, preventing shorts from disturbing the turnout and accessory decoders. Your 7 VA power pack, is it also powering the turnouts and lighting? I did everything in 3-6 month stages, the DCC EX base and RaspBerry Pi, adding the booster 3 months after that and then the turnout decoder 6 moths later observing operational differences and performance each step along the way. While I do have a computer and electronics background, I started in Oct2020 because of what this DC EX can do. Began with a couple bottles of Floquil paint, opened package of testor brushes and a 40 year old exacto knife( left from my 1980s HO set). Most commercial systems are more costly, especially with wireless throttle support, but are out of the box solutions.
I don't see in your case or in most cases having to add a $50 booster as a big deterrent. I think you will run into that with about any commercial DCC system you are going to buy for under $200 if you want to run more than 3-4 locos at the same time. The ProCab, very popular, won't power much more than the base DCC++EX system as it is rated at 2 amps. Adding boosters is very common for about any system that is going to run very many trains at the same time. With a larger layout one is going to probably want power districts anyway to make finding shorts easier and so that everything doesn't shut down any time there is a short anywhere on the layout. I'll be a single user but still have bought boosters to use with my layout and circuit breakers to further divide up the layout into 7 districts. I came close to going with one of the major systems before finding first DCC++ and then DCC++EX and would of had around $500 to have a system with a command station, a booster and also a wireless throttle. Now I have all of that and more for under $200. Sumner
I'm in N-scale and my DCC system is the original Digitrax Zephyr. It is only rated at 2.5 amps and I did a test to see if there was any chance of me overloading it. I ran a total of seven trains at one time, two of which had two engines each for a total of nine engines. They included a Bachmann DD40AX, which has two motors in it, and an Athearn Challenger with sound (the only sound engine I had at the time). None of them were running light, either - the shortest train was three Athearn Bombardier cars (not the easiest rolling cars around) and the longest was 25 Micro-Trains boxcars. There were also three lighted Kato Superliners (the old style with incandescent bulbs, not LEDs) among the cars. I think 2 amps would handle your 3 locos just fine. Motor only decoders add practically nothing to the current draw, about 0.01 - 0.02 amps for the microprocessor. Motor+sound decoders definitely add more, both for the actual sound and because the processor itself draws more, but not as much as many people think. There seems to be this assumption out there that sound locomotives are power hogs, but that's really not the case. I think it comes from the fact that some do draw excess current when power is first applied to charge their capacitors, but that can be designed around and I think most modern decoders no longer have that issue. The Loksound 5 decoder is rated 3 watts. At 12 volts it only takes 0.25 amps to generate 3 watts (theoretically, it would actually take a little more since no amplifier is 100% efficient), and that would be at full volume - how many people run their trains at full volume? Model Railroader used to include amp draw in their reviews, but for some reason they don't any more. I looked through at a few of the old HO sound loco reviews and a few draw over 0.5 amps when stalled (not a normal situation) but none of the ones I came across drew over half an amp when slipping. I would be very surprised if any modern HO scale sound loco drew more than 0.5 amps under normal circumstances and I think the DCC++EX could easily handle three locomotives with sound.
I would like to know what you mean by "they do run better." As I mention above, 2 amps should be plenty for three locos. If the new booster has a higher voltage then that could cause less stalling on dirty track, and if you changed the wiring when you added the booster better wiring could cause less voltage drop, but just having more power available when it's not needed should not make the locos run any better.
Ive ran 6 locos on the NCE power cab with out an issue with stock power feeding it.. 1 sound loco out of the six. power pack was12 @ 1.8 amp
@CSX Robert . Assuming your worst case 20mA per loco and lets for fun, say you have terrible 50% losses in poor wiring etc, of a 2A maximum, would mean you can run 50 locos on 1A remaining? NCE, as you know, is one of the most commonly used commercial DCC systems suggests 500mA per HO loco and 250mA for N scale and indicates that one can run up to 8 n scale locos on their basic 2.5A system. https://ncedcc.zendesk.com/hc/en-us/articles/203537009-Which-system-do-I-need-All-Scales Moreover, reviewing the specs on the LokSound 4, which happens to be the decoder in my Atlas Gold... Preceding this chart, an introduction... Loksound micro 4, presumably the least power demanding decoder of the family is advertised with a max draw of 750mA. One of the first questions Atlas asked last June prior to sending loco in for a mechanical repair was related to power. Atlas support mentioned to leave 1A for this loco. This seems to correlate to the chart. To reiterate as maybe I wasn't clear... , locomotives are not the only devices consuming power on my layout, rails connected accessory decoders for turnouts, lights, signals all will be drawing power from the track. Generally, accessories on DC layouts are either powered by secondary outputs on larger packs or separate power supplies. Having more headroom for instantaneous power needs like throwing solenoids just makes sense to me. If wiring gauge of 18 is ok, I'll try to use 16 or lower. If my speakers produce a desired level at 10 watts RMS, I'd buy a 20W RMS amplifier to avoid amplifier clipping when instantaneous loud passages occur. If I'm designing a rectifier circuit and the calculated current is 1 A, I 'll select a diode with an If max of 2A. There are 3 popular 2A motor shields that are referenced on the DCC EX site. Arduino, Deek Robot and DIY. While all 3 are rated at 2A max, I paid a couple dollars more for the DIY because the L298 chip package style has larger heat sink which will allow the L298 to run cooler. In my opinion, unless poor circuit design or faulty components, most electronic failures occur where heat is dissipated. In audio amplifiers as example, would be the power supply and final stage(s) of amplification. My suggestion is not to let the booster interfere or bias you away from DCC. You can go slow. For about $50, you can try DCC EX and see how it goes? Boosters are fairly easy to add later and in my case, I did not buy the booster until ready and had enough operational history before adding adding track powered accessories.
No, you misunderstood my statement. In answering the question about how much motor-only decoders would change current consumption, I said they would add 0.01 - 0.02 amps, you would still have the current draw of the locomotive itself, so if a loco draws 0.1 amps on DC, it will likely draw 0.11 - 0.12 amps with a motor-only decoder added. Yes, I have seen these numbers quoted often. I don't know where they originally came from, but generally speaking for non-sound locos they are overkill, although you can find some locomotives that will match or even beat these values (I've heard of "Blue Box" Athearn HO locomotives that draw an amp or more). The decoder's maximum current draw is how much current the decoder can supply to the motor and no N-scale motor I know of is going to draw anywhere near 0.75 amps under normal operating conditions. The decoder is only going to draw from the command station or booster the total of the current drawn by the motor, plus lighting, plus the decoder's processor and additional circuitry, plus sound, and in N-scale that total is very unlikely to exceed 0.25 amps. Having a lot of accessories running off track power will certainly make a difference, especially with solenoid thrown switch machines.
I interpret that .75A or 750mA reference in the introduction paragraph for the decoder alone as worst case load off the rails. To me, a manufacturer will promote best case and better power efficiency. Anyway, regardless of how or where NCE or Atlas got their numbers, if a problem occurs and one needs to contact, ample base or track power and base system manufacturer is among the first questions asked. I going to use the manufacturers suggestion as guideline or a baseline. Maybe I'm foolish but it works for me and have never had power related issues. Windows 11 runs on 4G RAM and 1G CPU, does anyone want to run 11 with those specs?? Apologize for any confusion... Unfortunately, throughout this thread, never indicated the word "can't" run 3 loco's with standard Arduino shield rated @ 1.3A cont or 2A max.
