Anyone have something set-up to monitor DCC track current? Sounds like it would be good to have a meter for each district visible on the control panel.
What do you think?
Gary
Our club uses a Digitrax system and we have 4 districts. We also have ampmeters for each district. I am not sure what brand they are and will not be there until Thursday.
https://tonystrains.com/rrampmeter-by-dcc-specialties/
This may work for you. I am ot sure if wee have this brand or not but it is similar.
I've throught about it. Looks cool. But I think overkill. Think about your layout and how many trains you possibly can run at a time. I know on my last two layouts, the answer was never more than the DCC system could supply, so I didn;t really care about how much current was being drawn. On the basement layout I am now designing, there will be multiple boosters, but more to reduce bus length than that I need all that power. As such - the really cool looking "power wall" with volt and amp meters would just defat the purpose - everything would have to be centralized and then fan out to the layout.
The only way to do this on the cheap is with Roob Paisly's current measuring circuit. It doesn't include the display, yoou use those cheap digital meters from ebay, but it does have the proper sense chip on it to properly read DCC current. FOr voltage - you can get cheap AC volt meters in a similar style, and if anything like the DC one I have, there is a calibration adjustment, so just calibrate it to read the same as a proper meter at normal track voltage and it will be fine.
I MIGHT put such a setup on each of my boosters, although I did not intend for the booster to be readily visible (likely a swing down shelf for each that keeps it hidden behind the fascia during normal operation but can be swung down to work on) so I'm not sure how useful it would really be.
Our 28x165 club layout uses 5 boosters (mostly for distance, again) and no one's bothered to put meters on them, and there haven't been any problems.
Again, it sounds like it would look cool, and I'm sure it does. I'm not so sure just how useful and worth the cost it would be. I think maybe if I modeled electrified lines I would have a power dispatcher, except then I would build my own measurement circuits to drive era-appropriate big analog meters. THAT would look cool for sure.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Like RR_Mel, I have built two of the Paisley circuits. I use the 20 ma current scale.
The voltage option, I use a large LED meter from ebay so anyone in the club can see it easily
I have a high wattage rheostat I clip across the tracks and lower the resistance to simulate locos on the track. The clubs NCE five amp Power Pro trips at about 4.97 amps.
The same meter, Harbor Freight meter indicates 13.6 VAC DCC voltage. My Scope measurements agree.
Some will tell you it is not accurate because you are suppose to use an RMS meter but this is model railroading, not rocket science.
I probe at the track connection, and with slow downs one the layout I probe the areas and see a lower voltage and know there is a connection issue. Has to be a loco in the area for testing. A load is needed.
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.
So I was looking for a way to spot trouble before I ran into the problem I had last weekend with the EB1 fault.
Gary,
IIRC, you have a Digitrax system, yes? The Power Cab actually has one built into the thottle that you can set up with a few key strokes. Unfortunately, once I got my Smart Booster (SB3a/SB5) that capability got overrided.
Randy, do you think that is something that NCE could add with a firmware update? My initial guess is that it would require a new board revamp to add it back in.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
I have an NCE Pro Cab with Radio system which i believe can also do the same thing. I want to monitor the voltage coming out of the Circuit Brealer to the Bus Lines.
Looks like the set-up recommended will do the trick
The RRampMeter will measure and display both voltage and amps (current draw). However, it is pricey and if you have a number of power districts, you would need one for each power district if you want to measure voltage and amps on the output side of each circuit breaker.
Alton Junction
Gary, your thread title indicates that you want to measure current (amps), but that EB1 problem seems to be a voltage issue. Didn't you report something like 13 volts on the input side but only 8 volts on the output side?
Yes Rich you're correct. So I guess I want to monitor VOLTS. I'll get this sooner or later.
Tom: the current sense is in the booster part of the PowerCab, so it would have to be in each booster in any expanded syste, and if you had more than one, there'd need to be some way of addressing each one, which would use up a cab address, of which there aren't a whole lot.
Rich: An RMS meter (one that just says RMS) would probably give a way off voltage reading on DCC. A plain RMS meter is calibrated for sine waves. Peak voltage for a sine wave is square root of 2 times the RMS voltage (about 1.41 and change). That's why a FILTERED DC power supply has an output voltage higher than the transformer secondard less the two diode drops in the rectifier. The filter capacitor charges to the peak voltage. No cap and you get a ripply lower DC voltage, still sine wave ripple. The filter cap will charge to the peaks of those ripples.
There are fancier meters that are marked as True RMS - such meters are generally calibrated to work with sine, square, and triangle waves. They can detect the waveform (within the supported frequency range, also give in the meter's specs) and report the proper AC voltage.
The rub with the cheap no form of RMS meters is that the peak of a bipolar square wave IS the RMS value. You can see the math here, if you really want to (it's calculus): https://masteringelectronicsdesign.com/how-to-derive-the-rms-value-of-pulse-and-square-waveforms/
Scroll down to where it starts with "But what if the waveform is bipolar". That describes the DCC waveform exactly. SO for a bipolar square wave, the meter needs to only read the peak, it doesn;t need to do any RMS calculation - the RMS voltage IS the peak. So those cheap meters work perfectly fine on DCC. Nothing fancy is needed, and in fact a mid-grade meter may provide WORSE results than a cheap one. I need to try each of my different meters and see what results I get. I have everything from the HF cheapo ones to fancy dual display 6 1/2 digit benchtop ones. Dual display means it can show two characteristics at the same time - like AC volts and frequency, or AC volts and DC volts (good for measuring power supply ripple), or volts and current.
rrinker Rich: An RMS meter (one that just says RMS) would probably give a way off voltage reading on DCC. A plain RMS meter is calibrated for sine waves. Peak voltage for a sine wave is square root of 2 times the RMS voltage (about 1.41 and change).
Rich: An RMS meter (one that just says RMS) would probably give a way off voltage reading on DCC. A plain RMS meter is calibrated for sine waves. Peak voltage for a sine wave is square root of 2 times the RMS voltage (about 1.41 and change).
I have a small layout, about 50' of continous run main track, and the trains run a nice even speed through all 4 blocks that make up the run.
Yes, blocks, as I set mine up for DC or DCC by gapping both rails.
Never felt the need for constant monitoring. But that's just my situation.
I would guess that if you had a huge layout, with many blocks / power districts, you might want to monitor track power.
Mike.
My You Tube
UNCLE ! I give up. Clearly there is no simple way for a guy like me to connect a reasonably priced Meter to monitor volts coming out of the CB to the track bus. I din't understand half of what you're all discussing. Probably there's no good reason to do it either. I purchased a TT Exchange Ramp meter and if decoders start doing their own thing again some time in the future I'll start by checking power supplied at each juncture.
I keep reding electronics and DCC posts and learn a little at a time. at some point I might be able to discuss waves and RMS and other items with the knowledgeable people.
Gary, if your model railroad budget will permit you to spend somewhere between $60 and $70 for a RRampMeter from DCC Specialties, do it. The RRampMeter can be used as a portable device, so you can move around with it, testing the voltage on the output side of each EB1.
Ordered one!
You will be pleased with the RRampMeter. In my experience, it is highly accurate and well worth the money.
gdelmoro UNCLE ! I give up. Clearly there is no simple way for a guy like me to connect a reasonably priced Meter to monitor volts coming out of the CB to the track bus. I din't understand half of what you're all discussing. Probably there's no good reason to do it either. I purchased a TT Exchange Ramp meter and if decoders start doing their own thing again some time in the future I'll start by checking power supplied at each juncture. I keep reding electronics and DCC posts and learn a little at a time. at some point I might be able to discuss waves and RMS and other items with the knowledgeable people.
Sure there is - go to the nearest Harbor Freight and get 3 or 4 of their $3 meters. Or what for a coupon and get at least one of them for free. They read accurate DCC track voltage. The why was the reason for my explanation of what all that RMS stuff is about.
If you get a HF meter - it's often cheaper to jsut get a whole new meter when the battery in them dies. The ones I have use a plain 9V battery but some of them use watch-type button batteries. Those can be expensive to repalce, although there are ebay sellers with lots of 100 of them for cheap - problem is about half of them are dead on arrival - but the actual cost for the still good ones is still a fraction of what you pay in the store for those kind of batteries. Just have the hassle of goign through them testing each one to throw out the bad ones.
I just have to say when I read Randy's explanation of the Harbor Freight meters and their batteries, it seems like a lot of hassle and a bunch of junk. If the meters and the batteries are that unreliable, how can you be sure of the measured results?
The RRampMeter runs off the very DCC power that is being measured, no batteries required. I have owned mine for over 10 years, no failures.
Randy wrote
They read accurate DCC track voltage.
Rich wrote
If the meters and the batteries are that unreliable, how can you be sure of the measured results?
That's not what he said at all. He said bulk batteries from ebay are unreliable.
I've never replaced the batteries in my harbor freight meters and they live in the garage for the past 5 years. Batteries are consumables, no surprise there.
At any rate in another thread, the OP showed us a pic of some meter measuring the track power at a fraction of what it is supposed to be. I'd say that was good enough to determine there was a problem, without spending another $55.
Henry
COB Potomac & Northern
Shenandoah Valley
Well, excuuuuuse me.
Hey, Henry, to each his own.
Am I searching for a DCC Meter on the HF site?
gdelmoro Am I searching for a DCC Meter on the HF site?
Search HF for meter or multimeter.
My HF meter shows 13.6 VAC right at the output terminals of my NCE Power Cab. The Scope agrees.
https://www.harborfreight.com/7-function-multimeter-98025.html
Just a plain multimeter. HF isn't going to know what DCC means.
I had one of mine finally have the battery die. I have them stashed all around the house (the meters, not batteries) and in this case it was a 9V one, so I used the old battery out of the smoke alarm - the reason for the recommended change interval on the smoke alarms is so they have a known good battery - I haven't seen a smoke alarm that kills a battery in a year for ages. There's plenty of life left in the old one to use the meter for another couple of years.
Were I to use them as panel meters - I'd probably just get a 9V DC wall wart adn splice the wires on, no battery at all.
Edit: Henry linked the one you want above. One word of caution - do NOT be tempted to measure you AC wall outlets with this thing. The probes and the meter itself are not properly protected for that sort of thing. It's perfectly safe for low voltage train stuff though.
BigDaddy https://www.harborfreight.com/7-function-multimeter-98025.html
I don't know if there is bias against the RRampMeter, but there certainly could be: the cost for a limited use AC/DC/DCC at 20-30 volts/10A max meter is $60. Also they have missleading statements "Costs less than DVMs that cannot measure DCC," which is not an accurate statement, if they said "...cannot measure DCC accurately," that would be better. And DVM is not what most model railroaders would buy or have, likely they have a DMM, yes there is a difference. I guess using the statement with DVM is more accurate because DVMs are strictly volt meters.
However, if you are looking for a voltage drop you only need a $6 HF meter (or free with coupon & another purchase) or any DMM. Doesn't matter if the DMM is not 100% accurate, measure the output on the lowest AC range possible at the circuit breaker and then various points along the tracks, until you find the voltage drop.
The $60 price for the RRampMeter is without an enclosure, add that and clip leads for another $25. Also as stated RMS voltage for a square wave (which DCC is) is the same as peak voltage which is what non RMS meters read so their statement "Measures true RMS Volts/Amps" while accurate makes the RRampmeter sound like it is way better than anything else by using technical terms most model railroaders do not understand. Prices quoted are Tonys, which is less than MSRP.
I'm not biased agains the rrampmeter. Just that you can buy a dozen or more HF meters for the price of one rrampeter. Or even get one for free.
In the case of DCC, as I explained above, a "better" meter might not be better. To accurately measure square wave signals at DCC frequency you neeed one or the other extreme - a cheap meter with absolutely no RMS calculation, or a high end one with a True RMS feture that cna handle more than just sine waves - and it needs to go up to the DCC frequencies. That usually puts you in the well over $100 category unless you are into restoring oolder meters - the 80's vintage Fluke 8060 I got for about $50 goes well over 20KHz for True RMS readings because it was originally designed for audio engineers. That meter was quite expensive back when it was new - and not just on account of inflation.
I've compared the HF meter to my reference standard I have, and at least within a narrow range, what you'd expect to see on a model railroad, both AC and DC are as accurate as you're going to get out of 3 1/2 digits. And there are meters out there selling for $20-$30 that use the exact same multimeter chip as the HF ones. With no additional fuse protection or anything to justify the higher price. For what it is - a low cost meter to test low voltage and low current, it's actually one of the better options. Because it both works AND works accurately. And it has other options for use that you don;t get with the rrampmeter - it has a resistance measurement so you can check resistors - which on some of these ones you get now, is almost a requirement since you can hardly see the colors or even when not color blind, a couple of the colors used look VERY similar. I don't bother any more - I just use a meter. And it has a continuity function with a beeper to test connections.
I have plenty of 'better' multimeters - but the HF one is what's in my railroad toolbox. I use the better ones for circuit design and analysis. If i want to check the track voltage around the layout - the HF ones works perfectly fine and is plenty accurate enough. Plus if I drop it and it hits the cement, I don't care too much, unlike if I did the same with the $160 one.
The rrampmeter is nice, at least the versions with the nice case on them, but it's mostly a single-tasker and a standard multimeter is often needed anyway for all the things the rrampmeter can't do. I'm of the Alton Brown school - he hates single taskers in the kitchen, I hate single taskers in the shop.
rrinker I'm not biased agains the rrampmeter.
I'm not biased agains the rrampmeter.