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.
You need to use an AC scale for voltage and it may not be very accurate because of the square wave output of your Power Cab.
I built up a Paisley circuit to measure DCC current and it works very good.
http://home.cogeco.ca/~rpaisley4/DCCammeter10.html
Check out Rob’s site, he has a lot of neat stuff for model railroading that is easy to build. He also sells printed circuit boards for his circuits as well as kits.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
As Mel indicated, you would measure AC, not DC, but a more reliable device than a multimeter would be a RRampMeter or a so-called “true RMS” meter.
The RRampMeter can be used in-line or portably, as opposed to in-line, to measure voltage anywhere on a layout. However, when using the RRampMeter to measure current, it must be used in-line, so it cannot be used portably to measure current.
I am not familiar with the operation or functionality of a true RMS meter.
Rich
Well 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 can read about the RRampMeter below. I got one when I was setting up my 2012 (current) first DCC layout. But I virtually never use it. Some people install on the fascia to see their current demand.
Hi Fender
For small applications I don,t know of any way to measure current except, in line.
The thing is, there is no current untill something is turned on. if you have a light bulb and a 120V source there is no current untill the light is turned on so nothing to measure.
I remember an instructer that compaired electric to water, Voltage is the height of the dam and current is the amount of water coming out of your pipe at the bottom.
Cheers and have a good day.
Lee
I’m one of the nuts that use meters in my control panel. I bought a couple of cheapo panel mount digital volt meters ($4) for my control panel. I’m using Rob Paisley’s circuits, the panel meters are mostly for show. The current meter will show increasing current as my trains climb my 3½% grades, again mostly for show.
My control panel is going through a massive redo for several new projects one of which is adding the DCC meters.
This is a drawing my proposed new control panel with the DCC meters.
https://drive.google.com/open?id=0B7gZp9MPvrm3SXJHeXVRMVpDbDA
PhotoBucket is down so I posted the picture on my Google Drive.
The PowerCab has an option to display current (amps). see pg 59 of 1.65 manual
A true RMS multimeter is used in the exact same manor as any other multimeter. The only thing special about them is that they will give you an accurate AC voltage measurement, even if it is not a standard 60 cycle (hertz) sine wave.
I have used a Harbor Freight digital multimeter using the AC scale. I have the Power Cab and I measure about 13.6 vac. I check right at the cab output and then check along the layout. Since the power pack is 13.9 vdc, I know the readings are accurate enough.
About the same thing at the club that uses the NCE Five amp, power pro.
DCC you must know is sometimes called a form of AC.
With your meter, check right at the cab. Use that reading as a bench mark. Check at different points on the layout but make sure a loco is in that area because you need a load to see a possible voltage drop.
I remember a few post where the user said proper voltage everywhere but put a loco on the layout and saw slow downs. Need a load.
Try the AC scale and let us know what you see.
Remember, this is not rocket science, just model railroading.
The meter I use also makes a very good DCC amp meter using the 20ma DC current scale with a few extra components as someone has said. I have a high amoerage rheostat I clip across the railsand the booster trips at about 4.97 amps at the club.
Rich
Accurately Measuring DCC V-AC Track Voltage
DCC uses a digital V-AC track power supply. As previously stated, to accurately measure digital V-AC you will require a RMS (Root Mean Square) V-AC volt meter.
There are special multimeters available that will measure V-AC (RMS). Fluke sells True (RMS) multimeters, but they cost way over ($100.00’s) each.
Sorry RR_Mel to de-rail your plans, you can purchase a digital Amp meter, but you can Not purchase a digital Volt (AC-RMS) meter.
I presently have a RRampMeter that is manufactured by (DCC Specialties), that I purchased from https://tonystrains.com/shop/?s=rrampmeter
DCC Specialties
http://www.dccspecialties.com/
They manufacture many different advanced DCC products and do not sell directly to the public, but only directly to Dealers.
RRampMeter
The only inexpensive device that accurately measures DCC (track) Volts/Amps.
http://www.dccspecialties.com/
There are (4) different versions available.
Learn More About RRampMeter
http://www.dccspecialties.com/products/rrampmeter.htm
RRampMeter Pictures
http://www.dccspecialties.com/products/rrampmeter-pictures.htm
You can use the RRampMeter to check your layout actual track V-AC power supply. (Not Amperage).
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
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize t
I paid about two dollars each for my meters and about maybe nine dollars for the amp meter parts.
If you have a layout with a couple boosters, cheap enough to cover both sections with it’s own amp meter.
I installed at the club with an over head digital display so everone in the room can see the current easily. At the club, I used Paisley’s voltmeter option.
I first did the meter like Mel did but realised the over head meter was better.
Yes the rrampmeter is nice but not absolutely necessary. It is nice if you do not like messing with electronics.
Rich
Sure you can. Home Depot sells one for $66.
Rich
Measuring DCC V-AC Digital RMS Voltage
Hello RR_Mel
So you claim to be an EE (electrical engineer) and also using a Rob Paisley DCC digital panel meters.
This Posting (DCC Meters)
DCC V-AC digital track Amperage can use Any type of Ohm (resistance) meter.
DCC V-AC digital track Voltage requires a V-AC (RMS) Voltage meter.
Fact (DCC Amp Meter)
DCC Circuits And Related Pages
http://home.cogeco.ca/~rpaisley4/CircuitIndex.html
1.) 5 Amp - DCC Ammeter (ZXCT1009) (PCB)
RR_Mel
Could you please inform all of us in this posting. Where has Rob Paisley posted on his web site, how to build a DCC digital V-AC (RMS) voltage meter (project) to measure actual V-AC (RMS) track voltage?
I’m not going to get this post locked arguing with you. As far as I’m concerned it would be much better if you moved to another forum, if they will allow you. All of Rob’s circuits that I’ve used over the last 15 years have worked very good. The Rob DCC meter circuits are accurate to better than .1 volts according to my Fluke and that’s all I care about. I will not respond to any more your disrupting posts!
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
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
I’ve used dozens of Rob’s circuits and all are excellent. I normally make my own circuit boards but I bought the DCC current board from Rob. I did a slight mod to it to expand the range.
His signaling system circuit is great.
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield
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.
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.
–Randy