In the high current modes (like the 10 amp range), the 'load' of a multimeter is negligible (possibly not for some super cheapy version). Current is measured as the voltage drop across a calibrated shunt resistor. It's when measuring low power devices that the effect of this voltage drop becomes noticeable. There are special low current devices and multimeters with such circuitry built in. This voltage drop is called the burden voltage.
For track power levels - not an issue.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Some years ago I built two five amp DCC amp meters using the below circuit. Cost about fifteen dollars some years ago.
http://www.circuitous.ca/DCCammeter10.html
I used a high amp rheostat to test it.
The club NCE five amp Power Pro tripped at about 4.97 amps and it used a Harbor Freight multimeter on the 20ma DC scale as one option.
I used a red LED volt meter option so the club could see it from anywhere.
A tree terminal device does the conversion.
This guy post circuits after testing them.
You can also buy a RRampmeter. More expensive. Google it.
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.
Mine does as well, but only if you are using it as a stand alone 2 amp Power Cab, since the Power Cab is also the power supply. I believe that once you install a booster, the Power Cab will not show the amps any longer as the Power Cab is no longer the power supply, only the controller, at least mine does not unless I am not using the SB5 booster, just the Power Cab.
I just want to know how close I am to needing to install another 5 amp booster to my system before I overload the 5 amp SB5 booster.
My Power Cab shows current very nicely.
I'm reading that AC or DC ammeters under 20-30 amps all will work the same. Only measuring 2-5 amps being used by the track max using an ammeter of 0-10 amp max range. My fluke doesn't have seperate selectors for AC or DC amps or milliamps, just milliamps. Also curious how much power the ammeter itself will draw, if it is a concern or negligable at this level of current draw.
B. BryceCan you use a standard 0-5 amp ammeter to measure DCC current coming out of the booster and being used by the track?
the current between the booster and track is also alternating.
you could measure the current between the power supply and booster. that would include current consumed by the booster circuitry itself which would be indicated without any track connection.
greg - Philadelphia & Reading / Reading
This is a long thread and if I missed something, please forgive, if not please answer. The question is NOT about DCC voltage, but measuring the current draw from the booster. Can you use a standard 0-5 amp ammeter (not voltmeter, not multimeter, just a plain old ammeter) to measure DCC current coming out of the booster and being used by the track? I am well aware of the difference between resistance (ohms) current (amps), volts, sine wave volts, square wave volts, ohms law and kirchoff's laws and I already have a fluke multimeter, harbor freight junk-o-meters and a RRamp meter. I just want to know if a plain jane every day panel mounted ten dollar ammeter will work or not.
They do here as well - that's why you see posts suddenly appear BELOW oens you already read, and you know it wasn't there the day before. That's a newbie posting with moderated status and one of the mods releasing the post.
See this person's first thread - first couple of posts (to get past the moderation period) were fairly reasonable. Only after he could post freely did it really go off the rails (no offense to Gerry Leone, his antics are MUCH more enjoyable, plus you actually learn a thing or two).
Personally, I've never cared for the word "troll" as it is often used on forums. I think "muckraker" is a much more appropriate moniker.
I'ved been involved with this forum for going on 14 years. It never ceases to amaze me how a new members first post(s) are complaints, or "versus", or trying to bully their beliefs and preferences to others.
Many of the other forums I belong to (i.e. F150, Smith-Wesson, Ford, APS, etc.) put newbies on a probation period wherein their posts are seriously reviewed to assue the "applicant" is sincere and not looking to "rake muck"..........
ENJOY !
Mobilman44
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
Punish me if you will. Based on past experiences, I stand by my statement.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
hon30critter Mark R. DO NOT FEED THIS TROLL. Maybe we should all send personal messages to Steven Otte to bring this guy to his attention. Dave
Mark R. DO NOT FEED THIS TROLL.
Maybe we should all send personal messages to Steven Otte to bring this guy to his attention.
Dave
Please don't. As I like to say, "People have a right to be wrong." It's not my job to vet every post for usefulness and accuracy. Ignore him if you can, correct him if you like, argue with him if you must, but calling another user a "troll" or the like counts as a personal attack. So if anyone gets punished from this thread, it will be the ones calling for admin action against a user who has not actually broken any rules.
--Steven Otte, Model Railroader senior associate editorsotte@kalmbach.com
lifeontheranchYou have to admit they look cool.
At least as cool as a tachometer in a car with an automatic transmission.
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
lifeontheranch You have to admit they look cool.
You have to admit they look cool.
Yes they do.
mfm37 You can add gauges if desired. Many like the extra info. I prefer simplicity: Run trains, fix problems if they arise, Run some more trains. Martin Myers
You can add gauges if desired. Many like the extra info.
I prefer simplicity: Run trains, fix problems if they arise, Run some more trains.
Martin Myers
Alan
Freelancing the LK&O Railroad
fender777Well I am not building anything to test' never heard of a ramp meter. I guess if my trains work I am good. So far they do. I thought their might be a standard No that the DCC controller puts out on the track when idle. Thanks
You surmise correctly. If they are running OK, you are good. Your DCC sytem already has a booster. Every DCC sytem has one to power the track. The booster is built in to your PowerCab. It will "put out" the listed voltage - check your manual. You can measure the output with an AC meter. Your reading may not be exact depending on the meter. It will be in the ballpark and close enough for most. Current draw is dependent on what is running. Nothing on the track, there's no current draw to measure. If your trains are running OK, then the POwercab is putting out enough voltage. Parked engines with decoders draw a negligible amount of current. Light bulbs and leds will also draw current.
When current draw begins to exceed the rating of your Powercab (1.5amps IIRC) the trains will stop because the powercab's internal overcurrent protection will trip. That is when it will be time to add a booster that supplies more current. None needed until (if) that should happen.
You can do the "quarter test" around your layout. This involves simply shorting the two powered rails to see if the Powercab's internal breaker acts. It should trip immediately when the rails are shorted. If not, increase bus size or/and add feeders. When the breaker trips immediately all over the layout, you are good. BTW, it's called the coin test because at least in N scale, a quarter works well to make the short circuit across the rails.
betamax Said website is owned and operated by TorStar Corp. (The Toronto Star's publisher). That being cleared up... Can we stop the silliness? The easiest way to measure the current flowing in your DCC system is to connect an ammeter in series with the power supplied to the booster. Yes, some current will be consumed by the booster in the form of heat being dissapated by various semiconductor and passive devices. But, Kirchoff says what goes in must come out, so the amount indicated is the current being demanded by the booster and all loads connected to it. Simple and doesn't add any problems or complications to the track circuit.
Said website is owned and operated by TorStar Corp. (The Toronto Star's publisher).
That being cleared up... Can we stop the silliness?
The easiest way to measure the current flowing in your DCC system is to connect an ammeter in series with the power supplied to the booster.
Yes, some current will be consumed by the booster in the form of heat being dissapated by various semiconductor and passive devices. But, Kirchoff says what goes in must come out, so the amount indicated is the current being demanded by the booster and all loads connected to it.
Simple and doesn't add any problems or complications to the track circuit.
The Not Secure warning is a result of the web site having not implemented SSL. Nothing to do with ads on the site.
That is why I answered with results.
Any scientist worth their salt will attempt to do an experiment to see if a person’s experiments are valid.
graymatter Just my two cents...I put a ampmeter between the 13 volt 1.8 amp NCE power supply and the power panel. I cut the positive wire and conected it to analogue made in America ampmeter. I am going to add an ampmeter to each power supply I add.
Just my two cents...I put a ampmeter between the 13 volt 1.8 amp NCE power supply and the power panel. I cut the positive wire and conected it to analogue made in America ampmeter.
I am going to add an ampmeter to each power supply I add.
That meter may not work as expected. Installing it the way you are describing would require a high frequency (more costly) type of AC ammeter as the DCC signal functions at a much higher frequency that standard AC current. It may not work correctly or may even be damaged.
Just my two cents...I put a ampmeter between the 13 volt 1.8 amp NCE power supply and the NCE power panel. I spice the meter in the positive wire between the DC power supply and the NCE power panel.
I am going to add an ampmeter to each power supply/booster I add.
EDIT: what I am suggesting is measureing the DC current from the DC power supply. Measuring the DCC signal can be done with an Ocilloscope and if the amplitude of the DCC signal drops... that would indicate the DCC system is being loaded down.
It would be much simpler to watch the current draw from the DC source that supplies power to the DCC system.
If you have an analoge meter you can make markers on the face.
Marks for the average current draw of one locomotive. A mark for two etc.
and a mark for the max current your DC power supply can safely handle.
if an ampmeter needle twitches wildly when the locomotive is in a particular location, that could indicate a trouble spot on the track or switch etc. This is why I prefer analogue to digital ampmeter.
Mark R is correct the analogue meter would not give an accurate reading of the DCC current. Just the DC current from the power supply going to the DCC PCB.
Like Paul, above, I don't use my RRampmeter as often as I thought I would.
One thing that I do when I use it to read voltage, though, is attach an automotive 1156 lamp as a ballast load. Reading voltage without any load is not really going to pinpoint any weakness as near as I can see.
Weather you use the RRAMPmeter or not, this data sheet is helpful in this discussion:
http://www.tonystrains.com/download/rramp-appnotes-df.pdf
Page three addresses the ballast lamp.
Imagine going around your house and poking volt meter test probes into the outlets. Chances are you'll get 115 to 120 volts, in North America anyway.
Does that mean you can plug a 5000 watt space heater into the outlet you just read good voltage from? Read the voltage again after the heater is turned on!
Actually the old Digitrax "Quarter Test" will let you know if you have any weakness in your feeders or rail joints.
Good Luck, Ed
A cheapy Harbor Freight meter will in most cases actually be MORE accurate than en expensive brand True RMS meter. Why? Because with a square wave the peak is the actual voltage, unlike a sine wave where the peak is square root of 2 times the average. You need calculus to prove it (area under the curve - or box in the case of the square wave). A True-RMS meter will measure the correct values for sine, square, and triangle waves, however they usually don't go up to DCC frequencies. I have an old Fluke 8060 that was designed to be used by audio engineers so it does True RMS up to 20KHz, but more modern ones often top out at around 1Khz.
The main reason for the RRAmpmeter is for the current measuring, the voltage is easy enough to do without special circuitry. Most meters have relatively inaccurate AC amp readings, even of standard 60Hz stuff. The circuitry used in the RRAmpmeter is available for DIY from Rob Paisley. At one point he was offering a circuit board of the DCC amp meter with the current sensor pre-soldered (it's a surface mount part only) so all you have to do is basic part soldering to complete the circuit.
Measureing curretn around the layout when it all comes from the same booster doesn't tell you much of anything,. Measuring voltage will help pinpoint poor wiring though. You don;t even need an accurate measurement for that - measure right at the booster terminals and then compare that reading to ones taken from the rails. At the farthest point away it should still be no more than .5V less. Exact reading in unimportant, it's the relative change that matters.
fender777 Using my multimeter what reading should I get to make sure I have the right amount of juice on any one area of my track , I use a NCE power cab on my shelf layout. I assume I set the meter to DC' Also when is a booster needed. Thanks for help.
Using my multimeter what reading should I get to make sure I have the right amount of juice on any one area of my track , I use a NCE power cab on my shelf layout. I assume I set the meter to DC' Also when is a booster needed. Thanks for help.
What do you mean by "juice?" If you mean voltage, then any digital meter that has the appropriate range in an "AC" mode (say 20 volts) will give you a good estimate....good enough to know that you're getting good scale voltage to the rails.
If you mean 'current', which is amperage, you need to make something work across the two rails. As mentioned, something like a tail light bulb drawing about 2-2.5 amps, or a locomotive drawing a string of cars behind it while it's in motion. Technically, some bit of current is being taken up by a decoder and a headlight, but most of us want a locomotive to be in motion so that we can see what it draws with two, six, twenty cars, or what difference it makes if it's on level tracks, a curve, or on a grade and climbing.
I'm by no means an expert in this, but I understand that you do need special measuring devices to accurately measure current draw across the rails, and one of those is the popular RAMPmeter.
richg1998 Yeah, Rob's circuits have always worked for me. Generally the only ones who say the meters are not good are those who don't use them. Again, this is model railroading, not rocket science. I worked at a NASA facility for fifteen years and worked with the best equipment. Rich
Yeah, Rob's circuits have always worked for me.
Generally the only ones who say the meters are not good are those who don't use them.
Again, this is model railroading, not rocket science. I worked at a NASA facility for fifteen years and worked with the best equipment.
GrandTrunk-HO GRANDTRUNK As usual your info is inaccurate and miss leading! I am using Rob Paisley circuits with cheapo digital panel meters that are as accurate as my $280 Fluke!!!! Your gobbledy gook isn’t needed on this post. I am a EE with over 40 years of experience in electronics. Mel
GRANDTRUNK As usual your info is inaccurate and miss leading! I am using Rob Paisley circuits with cheapo digital panel meters that are as accurate as my $280 Fluke!!!! Your gobbledy gook isn’t needed on this post. I am a EE with over 40 years of experience in electronics. Mel
GRANDTRUNK
As usual your info is inaccurate and miss leading!
I am using Rob Paisley circuits with cheapo digital panel meters that are as accurate as my $280 Fluke!!!!
Your gobbledy gook isn’t needed on this post. I am a EE with over 40 years of experience in electronics.
Mel