ok. thanks
greg - Philadelphia & Reading / Reading
gregc i'm trying to ask what they measure at the same point on the track (and same loading)
i'm trying to ask what they measure at the same point on the track (and same loading)
Rich
Alton Junction
gregci wonder how well calibrated RRampmeters are and how well they stay in calibration.
He is a real stickler for perfection when it comes to track power stuff.
gregc richhotrain I own three RRampMeters, is there a difference in votlage measurements between your RRampmeters? i wonder how well calibrated RRampmeters are and how well they stay in calibration. Qualcomm calibrated all lab equipment twice a year.
richhotrain I own three RRampMeters,
is there a difference in votlage measurements between your RRampmeters?
i wonder how well calibrated RRampmeters are and how well they stay in calibration. Qualcomm calibrated all lab equipment twice a year.
My DCC system is a 5 amp wireless PowerHousePro system. When I add a second booster a few years back and added a second panel mounted RRampMeter, the voltages were different so I adjusted the two boosters to match voltage outputs.
richhotrainI own three RRampMeters,
hbgatsf gmpullman Without a current flow there is little to no voltage loss. It is almost impossible to get a good stable voltage reading using a train running as a current load. Is that because of the low power requirements of a single locomotive?
gmpullman Without a current flow there is little to no voltage loss. It is almost impossible to get a good stable voltage reading using a train running as a current load.
Without a current flow there is little to no voltage loss. It is almost impossible to get a good stable voltage reading using a train running as a current load.
Is that because of the low power requirements of a single locomotive?
the current drawn by the loco varies. the auto bulb current is consistent.
as rich explained, the voltage drop depends both on the resistance and current, so any problems will be easier to measure with a higher load
nickle-silver rail ir roughly equivalent to 26g wire
Rick
gmpullmangmpullman wrote the following post 15 hours ago: mikeGTW Don't forget you are dealing with a narcissist / egomaniac +1 He sure has taken away the enjoyment of my participation in these forums. Thanks for speaking up.
Mike
gmpullmanThe idea of an automotive lamp is to provide some kind of load while reading voltage across the rails. Without a load it is easy to read nearly even voltage no matter where you place the meter leads. Once you clip a lamp, acting as resistance, on the test leads OR on the other end of the RRAmp meter you have introduced the potential for showing where the weak point of your track, feeders, joiners or point contact areas are.
This was very helpful information. Thank you!
It explains why when I was testing my mainline for voltage fluctuations with nothing running on the track I wasn't seeing any difference on my mulitmeter on any point on the track. I found it frustrating because I was getting slowing / hesitating locos at these points so the unchanging multimeter readings made no sense to me.
I will use this techique from now on for troubleshooting. Thanks!
- charles
selectorI think we have two ships passing in the night here.
Well, let me throw a tugboat in the mix, too.
The idea of an automotive lamp is to provide some kind of load while reading voltage across the rails. Without a load it is easy to read nearly even voltage no matter where you place the meter leads.
Once you clip a lamp, acting as resistance, on the test leads OR on the other end of the RRAmp meter you have introduced the potential for showing where the weak point of your track, feeders, joiners or point contact areas are.
I just ran into a similar situation with my 230V electric baseboard thermostat. I wasn't getting any heat in the room and the cheapest fix was to replace the line-voltage thermostat. But in testing it I was getting 230V at the heater and I was getting continuity across the contacts.
I went ahead and replaced it anyway. Once I ground the rivets off and opened up the old thermostat I could see why I wasn't getting any heat. One contact was nearly burned off. Still there was enough of a surface to allow 230 V. to get to the meter but under a 20 amp load of the heater, no dice.
Same with a model RR. You can have a dirty rail joint that may allow your meter to read the same, or very close, to what your source is but once you introduce a load, boom, there goes your continuity.
Go to page 4 here:
http://www.tonystrains.com/download/rramp-appnotes-df.pdf
"Nickle Silver rail is not as good a conductor electricity as copper wire and can be a significant part of the voltage loss. Rail joiners can also cause a loss in voltage. To determine the layout voltage loss the voltage must be measured at the rails when current is flowing. Without a current flow there is little to no voltage loss. It is almost impossible to get a good stable voltage reading using a train running as a current load. The best way to measure the loss is with some type of steady load. An automotive lamp turns out to be a good device to use as a steady load. They are cheap."
Goos Luck, Ed
doctorwayneAh, thank goodness for the simplicity of DC.
It is always good to know if one is over taxing their power supply. A unit might be able to work fine at 10% or 15% over capacity, but it is going to burn out sooner. As a kid I killed my original MRC Ampac that way (silly kid running 6 locos at a time. Not our nice low current draw ones but the 1960's vintage type).
gregc CSX Robert If by "good" you mean a true-RMS meter, than nothing, but I would be willing to bet most model railroaders don't have a true-RMS meter lying around. my understanding is that it's the frequency range of the meter. many are intended for measuring house voltages at 60 Hz. i understand why some modelers are better off with the RRampmeter richhotrain The purpose of the automobile bulb is to test for voltage loss along the layout. The automotive bulb tests for voltage "under load". the bulb doesn't test for voltage, the bulb provides a load (~2A for an 1156)
CSX Robert If by "good" you mean a true-RMS meter, than nothing, but I would be willing to bet most model railroaders don't have a true-RMS meter lying around.
my understanding is that it's the frequency range of the meter. many are intended for measuring house voltages at 60 Hz. i understand why some modelers are better off with the RRampmeter
richhotrain The purpose of the automobile bulb is to test for voltage loss along the layout. The automotive bulb tests for voltage "under load".
the bulb doesn't test for voltage, the bulb provides a load (~2A for an 1156)
I think we have two ships passing in the night here. There's the light bulb testing appliance, with pigtails, just to see if the rails have power, and there's the light bulb to prevent letting the magic smoke out of decoders in the affected area if there's hard short.
In the first instance, you quickly determine that you have power to the rails, so why is 'effect X' happening...a stall, intermittent performance in one or more locomotives in that spot....that kind of thing. In the second instance, you have a permanent in-line installation of the 1156, fascia mounted, and when it glows you know you have a short in it's controlled space. The reason people use it, apart from taking up the current and sparing decoders nearby, is that it lets the rest of the layout continue to operate if the total current draw isn't going to go into overload territory with the light bulb glowing.
And, even further, that is why some prefer a buzzer/ringer device over, or in addition to, the 1156 because if other unaffected locomotives continue to operate, especially if they're 'noisy', a person with her/his back to the 1156 might not realize he/she needs to clear a short.
mikeGTWDon't forget you are dealing with a narcissist / egomaniac
+1
He sure has taken away the enjoyment of my participation in these forums.
Thanks for speaking up.
[edit]
Forgot to mention one other nice feature of the RRAmp meter and that's the simple LED to indicate a DCC signal present. There are times when there's voltage on the rails but no DCC signal present. One glance at the meter will confirm this.
https://www.youtube.com/watch?v=HMxPKlafoCo
Regards, Ed
To all posters except spike totally agree and if someone wants a tool of anykind for their rr then get it I know I do
Back when I was a maintainer for the real rr I could get just about anything I needed
Don't forget you are dealing with a narcissist / egomaniac and that's just my opinion I might get banned for that one kinda like Kevin did for speaking out on the forum expert ;
LastspikemikeYour locomotive wasn't running right. You knew that already. How did knowing the actual current draw help you fix it? Could you not get that same information by measuring directly at the locomotive?
With the ammeter in my Power Cab I get a more accurate reading because it's specifically designed for measuring DCC current (vs using a DMM that measures only DC & AC voltage & current).
With the brass locomotive up on the rollerbearing stands and the shell removed, I could visually see the motor struggling and binding. The motor housing also became very warm to the touch. What I could not determine the extent of is how much (quantitatively) the motor was struggling in terms of current draw.
Visually watching the fluctuations in the current confirmed that there was some sort of internal binding going on inside the motor housing, which is generally a sign that an electric motor is bad or going bad. Squeezing the motor housing slightly also showed me how that affected the operation of the motor - good & bad.
When I installed the replacement (coreless) motor, I wanted to see how much current it drew in respect to the LokPilot 5 decoder. As mentioned on pg. 1, at speed step 001 the motor was drawing only 0.02A. At speed steep 030, it had only increased to between 0.04-0.06A. That confirmed to me the replacement motor was operating very efficiently and well within the acceptable range for the decoder.
If you'd like to read the details and the troubleshooting process, you can go to this thread posted back in Aug '21, which, ironically, you commented on no less than 4 times...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
gregca meter designed to measure 60 Hz would certainly have a problem measuring a sine wave at DCC frequencies
True, I did not say the frequency was irrelevant, I said the issue is "as much" the shape as the frequency. If the meter was designed for a 10khz sinewave it would still be incorrect.
CSX RobertIt's as much the wave shape as it is the frequency range of the meter.
a meter designed to measure 60 Hz would certainly have a problem measuring a sine wave at DCC frequencies
DCC is ~10kHz. the harmonics of a square wave easily require 3x that.
CSX RobertThe relationships between average, peak and root mean square voltage are different bewteen a sinewave and a a square wave.
they are all different for a sine wave, but they are the same for rectified a square wave (i.e. Vpk = Vavg = Vrms).
if you account for the drop thru a bridge rectifier (~1.4V) you should be able to very accurately measure DCC with a DC meter.
this is probably what the RRampmeter does.
gregcmy understanding is that it's the frequency range of the meter. many are intended for measuring house voltages at 60 Hz
It's as much the wave shape as it is the frequency range of the meter. Most multimeters measure the avergae voltage and are calibrated to give the correct RMS reading for a sine wave. The relationships between average, peak and root mean square voltage are different bewteen a sinewave and a square wave.
gregc richhotrain The purpose of the automobile bulb is to test for voltage loss along the layout. The automotive bulb tests for voltage "under load". the bulb doesn't test for voltage, the bulb provides a load (~2A for an 1156)
richhotrain
The purpose of the automobile bulb is to test for voltage loss along the layout. The automotive bulb tests for voltage "under load".
LastspikemikeYou don't need to know that. All you need to know is the locomotive runs badly. Take the shell off and find out why.
one way to find out is to measure the current drawn and the voltage on the motor.
it would be helpful to know what the motor draws when running correctly
CSX RobertIf by "good" you mean a true-RMS meter, than nothing, but I would be willing to bet most model railroaders don't have a true-RMS meter lying around.
richhotrainThe purpose of the automobile bulb is to test for voltage loss along the layout. The automotive bulb tests for voltage "under load".
Lastspikemike So two reasons: maybe helps diagnose a poorly running locomotive and helps you initially size your powerpack. Any other reasons to acquire these devices?
So two reasons: maybe helps diagnose a poorly running locomotive and helps you initially size your powerpack.
Any other reasons to acquire these devices?
See my previous post.
Pete.
The current varies with load on the motor both in DC or DCC modes. A single locomotive running on level track by its self draws very little current. As you add cars the current increases then through in a grade with cars it increases even more.The ammeter shows the amount of power needed to do the job. Very few locomotives draw the same amount of current needed. Driving a car is different from model railroading. The way one determines how much power a car takes is at the gas station. On my layout I monitor the ammeter to see how much power a locomotive takes. Much like blood pressure, some never check it, I do. Like high blood pressure can be very bad so can high current in a motor.My era is the 1950s with a mix of steam and diesel, no two are the same. Most have been remotored using neodymium magnet motors, some with dual motors. I find that monitoring the current of my locomotives gives me some insight on their operating status, you know, the warm and fuzzy feeling that everything is OK.
Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
How about using the RRampMeter to check for voltage drop? So, now, three reasons.
LastspikemikeYou don't need to know that. All you need to know is the locomotive runs badly. Take the shell off and find out why. Although, I have an open mind if somebody wants to explain why you need to know anything other than the locomotive isn't working. These are very simple machines. Very simple. Wire them correctly and they will run. Mechanical problems are the motor is bad or the gears broken or incorrectiy aligned.
I'm not talking about locos that run badly. You can have a very wide range of current draw for locos that run well. Say I've got 5 amps and I want to know how many of my locos I can run at a time. Well, it's going to depend on how much current the locos draw. Sure, I could just add locos until the booster trips, but since different lcos draw a different amount, it's likely going to depend on which locos I choose. If I did a test and could run 10 locos, but I happened to choose all low current draw locos, if I throw in a few higer current draw locos the next time around I may not be able to run as many.
Lastspikemike You don't need to know that. All you need to know is the locomotive runs badly. Take the shell off and find out why. Although, I have an open mind if somebody wants to explain why you need to know anything other than the locomotive isn't working. These are very simple machines. Very simple. Wire them correctly and they will run. Mechanical problems are the motor is bad or the gears broken or incorrectiy aligned.
You don't need to know that. All you need to know is the locomotive runs badly. Take the shell off and find out why.
Although, I have an open mind if somebody wants to explain why you need to know anything other than the locomotive isn't working.
These are very simple machines. Very simple. Wire them correctly and they will run. Mechanical problems are the motor is bad or the gears broken or incorrectiy aligned.
Lastspikemike Your locomotive wasn't running right. You knew that already. How did knowing the actual current draw help you fix it? Could you not get that same information by measuring directly at the locomotive? So, what else would you use this real time current/voltage display for?
Your locomotive wasn't running right. You knew that already. How did knowing the actual current draw help you fix it? Could you not get that same information by measuring directly at the locomotive?
So, what else would you use this real time current/voltage display for?
Most of us are loan wolf operators. Picture this. I'm doing some switching in my yard with one diesel switcher. All of a sudden it stops no lights no sound no motor. Is an open in the track wiring or the locomotive? Is it a short from a cut of cars on a closed turnout? One glance at the meter will tell you if it's a short or open. So you give the locomotive a push and the lights come on but still no movement. One glance at the meter reads .001 amp. So you push the locomotive a little further and you have sound, lights and motor. Very quickly you have diagnosed a bad solder joint in that track section. Without digging out your multimeter, test truck, and scratched a raw spot on your head.
Now say you have the same scenario. Pushing the locomotive cured the issue until the front truck turned left and it stalled again but came back. The meter jumping in amps but voltage remains constant will undoubtedly lie with a bad connection in the locomotive.
Having the right information is key to successful troubleshooting. I have known guys take their truck into a shop because of coolant in the oil. After a $20,000 engine overhaul the same issue. A proper diagnosis the first time would have shown a leaking head gasket on the $500 air compressor was the culprit all along.
hbgatsf Rich, I saw your thread about testing your engine facility, https://cs.trains.com/mrr/f/744/t/285033.aspx. As I said in starting this thread I don't understand how this electrical stuff works under the hood. Can you explain in simple langauge the need for the light bulb? Rick
Rich, I saw your thread about testing your engine facility, https://cs.trains.com/mrr/f/744/t/285033.aspx.
As I said in starting this thread I don't understand how this electrical stuff works under the hood. Can you explain in simple langauge the need for the light bulb?
For example, on my layout, the voltage at the booster is 13.5 volts. Without a load, I also measure 13.5 volts at the end of the bus. But, when I add an 1156 automotive bulb on the output side of the RRampMeter, under load the RRampMeter measures 11.3-11.4 volts at the beginning of the bus (actually the rails right at the first pair of feeder wires.
As I move down the layout, every 5 feet or so, I get the following voltage readings under load: 11.2-11.3, 11.1-11.2, 11.0-11.1 etc., all the way down to 10.7-10.8.That is "voltage drop".
The loss of voltage is not that dramatic on my layout, but that is because I use relatively short lengths of bus. On my old layout, I used a continuous loop of bus wire (unconnected at the other end of the loop. I experienced voltage loss at the end of the long bus measuring more than 1.5 volts, resulting in slower speeds of locomotives at that point(s) of the layout.