Thanks Cadman , I'm already checking into the Rramp meter. Checked them out and seen the videos on U Tube, Jim
Use the digital Rramp meter from American Hobby Dist. 1.800.671.0641.
This meter can be panel mounted or directly touched to the rails and reads Voltage and Amperage (3 digit 0.00) constantly. It is made specifically for DCC.
You guys are beyond me with all this info, I have knowledge in electronics but this a little past what I have been taught and learned thru the years. Thanks for all the input, I will try and sort it out as I go, Jim.
Not a bad idea to monitor the power supply to the booster, but not for the reason that meters ont he output might interfere with the booster's short protection. Even the cheap Harbor Freight meters have 10's of megaohms imput impedence (if I had one of my half dozen sitting here I could get the exact figure), which means the circuit under test doesn;t really see any effect from the meter being there. The current meters, at least the little 3 pin SMT ones used in Rob's circuit and presumably in the RRAmpmeter work by measuring the voltage drop across essentially a piece of wire - less resistence than 50 feet of #12 bus wire.
Sure there is SOME effect - you can't observe without affecting the outcome, but the design of test equipment is such that it induces as little effect as possible. An ammeter is in series, so the only way it could prevent a booster from tripping is if the resistence is so high that it restricts current flow to less than the booster trip point - this is counter productive to the task of measureing current flow, and is simply not done. A volt meter is in parallel, so in no way can reduce the ability to sense a short or overload - in fact it minutely contributes an additional load on the booster, again though since the imput impedence is in the neighborhood of megaohms, it's like putting a 10 megaohm resistor across the rails - undetectable without fairly expensive instruments. Minuscule even compared to just one car with a 10K resistor wheelset - 1000x less assuming 10M impedence on the meter. Meaning you need to hook 1000 voltmeters up to equal the lod of just one resistor detection car.
Yes, now that would be my ultimate geek setup, each power supply monitored on the AC input and the output side, plus each booster monitoroed on the output. 3 sets of meters for every booster and power supply combo. And if the booster output is furhter divided by circuit breakers - you guess it, monitors on each breaker channel too. Would make the layout look more like a space craft than a model railroad depicting a pre-spaceflight time period. And be so absolutely overkill it isn't funny. But definitely awe inspiring. And expensive, for all those meters. But 'simpler' in wiring than a scheme were one set of meters could be switched into any of say a dozen power circuits - voltmeters are easy, simple double pole rotary switch could connect one volt meter to as many circuits as the switch has poles, with little chance of any fault causing problems. Switching ammeters though - much more complicated.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Why not just install ammeters on the power input to the boosters? It will tell you what is going on, as current in equals current out, or in this case, pretty close. The amount indicated would show the current demanded by the booster for track power.
I would be leery of additional loads in the track circuit, as this can interfere in the proper operation of the circuit protection.
As to crossing from one district to another, make sure the gaps are positioned correctly, and there is a ground return (heavy wire) between the two boosters, as well as the phasing being correct. Otherwise the LocoNet cable has to provide the return and that slows the autoreverse when things are out of phase.
Be sure to do the "quarter test" as well.
Not saying there's anything wrong with what you did, but for an example, let's assume the layout runs in a straight line, 100 feet long. You cna put both boosters in the middle, then each has no more than a 50 foot run to the furthest point. But you could ALSO put the boosters at the 1/4 point on each side - 25 feet from the end, 25 feet from the middle. Then each booster has a maximum bus run of only 25 feet.
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vs
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Significantly shorter bus runs the second way.
Thanks Randy, both my boosters are dead center of the layout with the same amount of wire for the buss. That was one thing I tried to make sure of when I designed it thinking of the power distribution. So far its been great, each main doesn't seem to have any power loss that I can hear or see from the loco's. I also have a 3rd booster for my yard which is 42 feet long and15 tracks wide and the engine facility so you can see why I have concerns about the power, so I've watched out for the power use by keeping everything equal and separate. It might be overkill but it works for me and everyone that operates. Jim.
Amps are probably more useful than volts, especially since DCC tends to react quickly to shorts and opens the circuit, dropping voltage to zero. It's more useful to test voltage with a handheld meter at various spots around the layotu to make sure there isn;t any excessive loss in the bus and feeder system - getting 15.2 volts at the booster terminals but only 13.4 at that distance yard measured on the rails is probably a sign of a problem. Current though, you can get an idea of just how much power you need, up to the trip point.
I've tossed this one around myself. One of the fetured columnists in that free online model railroad magazine has set up his DCC equipment centralized, with displays for volts and amps. It sure looks neat. I tend to think that centralizing all your boosters is somewhat counterproductive - the idea being to reduce the length of the bus wire, which seems to me to be easier to accomplish if you distribute the boosters around the layout near the areas they are powering.
I've had those same dreams though, of a whole rack of pwoer supplies for the entire layout, with gleamign digital displays for voltage and current....
I was just wondering if it was worth the time and money just to keep an eye on the voltage. I went looking for the ramp meter it seems like something I should get just to be safe. I have all the same wiring for all my track and boosters I think its all 12 gauge wire.I dont have anything else connected to my track wiring, any add ons have their own power supplies.I was just looking for opinions from other members if they used them. My mains are about 350 feet each with a 40 foot passig siding for each main so I was wondering about the voltage and amperage drop, thats why I have a booster and seperate power supplies and Ihave them both phased the same for each main line. I have 2 good volt - amp testers mabe I'll just hook them up and watch them. I've never had a power problem in 6 years and hopfully never do but just as soon as someone wants to see it run the gremlins come out of the closet. Thanks for your imput, always best to check in advance to see if someone else has been there. Jim.
There should be no issues with trains crossing power districts, each with its own set of meters. Assuming you can run trains across the gap now without a problem - the key is having a heavy (same as track bus) wire connecting the GND terminals of each booster. Without this, the thin Loconet cables could be called upon to carry the full booster current, and that's not such a good idea.
A (relatively) inexpensive panel meter would work. If it's adjustable - you could calibrate it with a meter capable of reading the DCC square wave accurately, but the main thing with voltage is that it is the same all the way around the layout - so if your meter reads 13.6 and the fancy expensive meter reads 14.1m its not really that big of a deal, as long as BOTH of yours read 13.6.
For current - a cheaper alternative to the RRampmeter is found on Rob Paisley's electronics site, he ahs a small board with effectively the same current sensors in it used by the RRampmeter for not a lot of money - available fully assembled, too, in case that's not your ball of wax. It hooks between the rail feed and an inexpnsive meter - you cna get surplus panel meters if you want to make somethign permanent - to give an accurate mearuement of current flow.
I have aan expensive meter that reads about the same AC voltage. Maybe two tenths dif but this is not rocket science. River counters will disagree.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I have three cheap digital meters from Harbor Freight for model railroading, They all show 13.6 volts AC with the NCE Power Cab and NCE Power Pro.
A few components allowed me to make a DCC amp meter for about than ten dollars. I use the 20ma DC scale on the cheap meter. A couple three terminal devices change the DCC to DC for the meter.
The DCC systems trip at the proper level for each system.
Get a Ramp Meter.
Our club had DC volt and amp meters for DC but were useless for DCC. DCC is essentially an AC voltage with digital info. A Scope will show square wave AC you might say. Equal plus and minus transitions in the wave form. DC meters will not respond.
I was looking at a dual digital volt and amp meter for my layout. It is good for 0-30 volts and 0-30 amps. I was wondering if anyone else has these installed on their layouts and if so how do they work for keeping track of your usage while running trains. I might add that I am using 2 Digitrax boosters 1 each on 2 separate insulated mains so I think I would need 2 meters correct? If one train crosses over from one main to the other would it create any problems? I run consisted sound loco's sometimes 2-3 together. I am using the 5 amp systems. Thanks Jim.