csx robert, I think my feeble brain is starting to catch on. Thanks all for your inputs.
yvesmary Rich, Both sides of the meter have contacts spaced to fit on the rails. You put one end on the rails and clip the lamp to the other end.
Rich, Both sides of the meter have contacts spaced to fit on the rails. You put one end on the rails and clip the lamp to the other end.
When the RRampMeter is used portably, that is hand held against the rails, you can use either the left side contacts or the right side contacts to measure voltage on the rails.
You can also use the RRampMeter portably by testing voltage with the left side contacts while clipping an 1156 automotive bulb to the right side contacts to simulate load. Since an 1156 bulb draws 2.1 amps, you will get that 2.1 amps reading on your RRampMeter.
The thing to note about the RRampMeter, though, is that when used portably, it cannot measure amps on the layout because the right side contacts are not on the rails.
I don't even bother to use my RRampMeter as a portable device. I just leave it wired in line so that I can see voltage and amps at all times.
Rich
Alton Junction
richhotrain yvesmary Rich, Both sides of the meter have contacts spaced to fit on the rails. You put one end on the rails and clip the lamp to the other end. When the RRampMeter is used portably, that is hand held against the rails, you can use either the left side contacts or the right side contacts to measure voltage on the rails. You can also use the RRampMeter portably by testing voltage with the left side contacts while clipping an 1156 automotive bulb to the right side contacts to simulate load. Since an 1156 bulb draws 2.1 amps, you will get that 2.1 amps reading on your RRampMeter. The thing to note about the RRampMeter, though, is that when used portably, it cannot measure amps on the layout because the right side contacts are not on the rails. I don't even bother to use my RRampMeter as a portable device. I just leave it wired in line so that I can see voltage and amps at all times. Rich
That's what I wasn't understanding .... why do you even care what the current reading of the bulb is ? How is that relevant to anything other than how much current the bulb draws ?
I can understand wanting to know the current draw of items (engines, lights) attached to/on the rails - THAT would be useful, but what's the purpose of knowing what the current draw of any given bulb attached to it ?
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
The purpose of using an RRampMeter with a bulb attached is to check for voltage drop due to inadequate wiring.
Mark R. why do you even care what the current reading of the bulb is ? How is that relevant to anything other than how much current the bulb draws ? I can understand wanting to know the current draw of items (engines, lights) attached to/on the rails - THAT would be useful, but what's the purpose of knowing what the current draw of any given bulb attached to it ?
why do you even care what the current reading of the bulb is ? How is that relevant to anything other than how much current the bulb draws ?
Yeah, I have always wondered the same thing. Here is what the RRampMeter manual has to say about it:
Measuring Layout Voltage Drop and Loss
With the lamp connected to the meter, it is easier to spot check areas of the layout. With the lamp connected to the rails, it is easier to check out the voltage loss of the wiring by moving the meter to varying points in the feed wiring.
CSX Robert The purpose of using an RRampMeter with a bulb attached is to check for voltage drop due to inadequate wiring.
Doesn't the thing measure volts without the bulb attached ? I can check voltage drops with my digital meter no problem, or does the internal battery / circuitry automatically add a load of some kind in the process that RRampmeter doesn't ?
Mark R. CSX Robert The purpose of using an RRampMeter with a bulb attached is to check for voltage drop due to inadequate wiring. Doesn't the thing measure volts without the bulb attached ?
Doesn't the thing measure volts without the bulb attached ?
Yes.
If you just hook the meter on with no load, you are seeing the no load voltage, technically the meter circuit puts a slight load (it SHOULD be slight, a high input impedence). Even if you wired the layout with telephoen wire 50 feet away fromt he booster, the no load voltage should show no drop - you don't get voltage drop int he wires until there is a load, Ohm's Law, E=IR, if the I (current) is really low, you can have quite a high R (resistence) before the voltage lost becomes significant or measurable. A decent meter will put as little influence on the circuit under test as possible. It's impossible to measure things without slightly affecting them, but you can make that effect as insignificant as possible with the design of the test instrument.
Add a load, and then you can see what really happens. It's likea cheap wall wart, maybe rated for a nominal 12 volts, you plug it in and connect your voltmeter, even one liek the cheap Harbor Freight ones, and you see 16 volts, or more. Hook it up to half its rated load, and check the voltage again - it might be LESS than 12 volts.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
richhotrain Mark R. CSX Robert The purpose of using an RRampMeter with a bulb attached is to check for voltage drop due to inadequate wiring. Doesn't the thing measure volts without the bulb attached ? Yes.
It will measure voltage, but not voltage drop. To measure voltage drop you have to have a load, that is the purpose of the light bulb. Voltage drop is the difference between the source voltage and the voltage at the point you are measuring and is directly proportional to the load(voltage = current x resistance). No load, no voltage drop.
Got it.
CSX Robert It will measure voltage, but not voltage drop. To measure voltage drop you have to have a load, that is the purpose of the light bulb. Voltage drop is the difference between the source voltage and the voltage at the point you are measuring and is directly proportional to the load(voltage = current x resistance). No load, no voltage drop.
Not to argue the point, but that was all that Mark was asking, does it measure volts.
What I find most useful about the RRampMeter is not its portability but as an in-line measuring device to show voltage sent out to the layout and the and the current draw in terms of amps. I have a 5 amp booster, and the draw on my layout never exceeds 2.5 amps. The voltage is fairly constant at 14.7 to 15.6. I just find that useful information. MY RRampMeter is mounted on a shelf with my command station and booster, so the readouts are always present and always viewable.
richhotrain CSX Robert It will measure voltage, but not voltage drop. To measure voltage drop you have to have a load, that is the purpose of the light bulb. Voltage drop is the difference between the source voltage and the voltage at the point you are measuring and is directly proportional to the load(voltage = current x resistance). No load, no voltage drop. Not to argue the point, but that was all that Mark was asking, does it measure volts. What I find most useful about the RRampMeter is not its portability but as an in-line measuring device to show voltage sent out to the layout and the and the current draw in terms of amps. I have a 5 amp booster, and the draw on my layout never exceeds 2.5 amps. The voltage is fairly constant at 14.7 to 15.6. I just find that useful information. MY RRampMeter is mounted on a shelf with my command station and booster, so the readouts are always present and always viewable. Rich
But to measure the current of your LAYOUT, it must be connected in SERIES with your booster output, correct ?
Yes. In the case of using the light bulb, the current reading should be fairly stable, at whatever the light bulb draws - however the purpose of that is not to see the current, but to see the voltage, the voltage under load. If you just touch one end to teh rails without the light bulb, you are reading the no load voltage, which, barring a REALLY bad wiring error or a complete open circuit, should be the nominal booster output voltage no matter how adewuate or inadequate the bus and feeders are. You can get 14 volts through telephone wire size bus wires, but as soon as you put a load on it, you will have a voltage drop and you won;t see a 14v reading any more.
You can;t tell a voltage drop if the meter is between the booster and the layout. With more than one booster, you can rig up a complex of switches and use one meter to display both, one at a time, or you need a second meter.
To check for voltage drop, you don;t need a fancy meter. A cheapy Harbor Freight meter will read close enough - the key is getting the SAME reading at all places - so what if it read 13 volts adn the RRampmeter says 16? If you have 13 everywhere with the cheap meter, then you don;t have voltage drop. Plus the difference is likely much less than 3 volts
yvesmaryRich, if your RRampMeter is mounted with your Command Station can you tell if there is a voltage drop somewhere and where it would be? If you add an extra booster do you connect another RRampMeter too?
When the RRampMeter is wired in-line, voltage drops on the layout will not be measured by the meter. But, that has never mattered to me because I only wanted to read voltage output at the site of the command station and the current draw from the booster. As Randy pointed out, there are other ways to read voltage drops on the layout.
Recently, I had planned to add a second booster on my layout, in which case I would need to add a second RRampMeter to be used in conjunction with that second booster. But, I wound up sticking with one booster and dividing the layout into four power districts, each protected with its own circuit breaker.
Incidentally, that does raise a question in my mind. My plan is to install a PSX-4 and daisy chain the primary bus wires through the four PSX circuit breakers to provide power to the breakers. Then, I would run a set of sub-bus wires from each PSX to each power district. I presume that my RRampMeter will still be able to measure amps being drawn from across the layout as long as none of the breakers is tripped. Is this correct?
If you hit the lottery you could get 4 more RRampmeters and put one in each breaker section.... your panel would start looking like the inside of a power plant though.
The meter between the booster and the breaker will show the whole layout draw and voltgae at the booster. If you put it between any of the breaker outputs and the layout, it would show the power draw in that section. A fairly cheap alternative to the RRampmeter is a circuit that Rob Paisley has that you hook a voltmeter to (current is measured by the voltage drop across a calibrated load) which means there may be an inexpensive way of having a dedicate ampmeter on each section - I'm thinking about it, if I can put it together cheaply enough. It would look cool, mostly. So I'm not about to spend the price of a locomotive on something just to look neat.
You will only be able to read the current of the entire layout with the RRamp meter between the booster and the PSX units. Installing DPDT switches in the power district busses after the PSX's to shut off each district will enable you to read the current of any district by shutting off the other three and will aid in troubleshooting a problem. I just bought another RRamp meter so I can still read the track voltage anywhere on my layout. I model in N scale. Six locos, two with sound running at scale speed pulling trains up a 2% grade draws only 0.81 amps. the RRamp meter draws 0.03 amps itself. I have the PSX breakers set for 1.2 amps.
rrinker If you hit the lottery you could get 4 more RRampmeters and put one in each breaker section.... your panel would start looking like the inside of a power plant though.
Randy, the power plant look appeals to me greatly.
If you put together that Rob Paisley concoction, let me know. I may hire you to build one for me.
retsignalmtr You will only be able to read the current of the entire layout with the RRamp meter between the booster and the PSX units. Installing DPDT switches in the power district busses after the PSX's to shut off each district will enable you to read the current of any district by shutting off the other three and will aid in troubleshooting a problem. I just bought another RRamp meter so I can still read the track voltage anywhere on my layout.
You will only be able to read the current of the entire layout with the RRamp meter between the booster and the PSX units. Installing DPDT switches in the power district busses after the PSX's to shut off each district will enable you to read the current of any district by shutting off the other three and will aid in troubleshooting a problem. I just bought another RRamp meter so I can still read the track voltage anywhere on my layout.
I like that idea a lot.
I may try that - the circuit from Rob is available assembled, you just need to connect a voltmeter of the appropriate range to it and it displays the current. My last thought on the matter was to aquire some of the Harbor Freight meters on the cheap (you can get them for $3, sometimes free if you watch the coupons) and use a power supply to replace the batteries and somehow mount them in a panel so all you see is the LCD.
Rob offers the thing built and ready for $14, then you need either a meter that reads milliamps, the HF meter will do, or you need a 10 ohm resistor and a 200mv meter - Rob has a link to one that costs less than $9. So it would be a bit less than $25 per to build in permanent ammeters for each zone, plus the meter needs a power supply (9V DC, one wall wart can probably power multiple meters).
Here is Rob's device: http://home.cogeco.ca/~rpaisley4/DCCammeter10.html
This is essentially what's inside the RRampmeter for the amp section.
rrinker My last thought on the matter was to aquire some of the Harbor Freight meters on the cheap (you can get them for $3, sometimes free if you watch the coupons) and use a power supply to replace the batteries and somehow mount them in a panel so all you see is the LCD.
My last thought on the matter was to aquire some of the Harbor Freight meters on the cheap (you can get them for $3, sometimes free if you watch the coupons) and use a power supply to replace the batteries and somehow mount them in a panel so all you see is the LCD.
Randy, I don't see that meter on the Harbor Freight web site. Can you point me to it?
richhotrainI don't see that meter on the Harbor Freight web site.
Here is a typical: http://www.harborfreight.com/7-function-multimeter-98025.html
Thanks, maxman.
I wonder if that is what Randy was referring to because he mentioned a $3 price.
rrinker If you hit the lottery you could get 4 more RRampmeters and put one in each breaker section.... your panel would start looking like the inside of a power plant though. The meter between the booster and the breaker will show the whole layout draw and voltgae at the booster. If you put it between any of the breaker outputs and the layout, it would show the power draw in that section. A fairly cheap alternative to the RRampmeter is a circuit that Rob Paisley has that you hook a voltmeter to (current is measured by the voltage drop across a calibrated load) which means there may be an inexpensive way of having a dedicate ampmeter on each section - I'm thinking about it, if I can put it together cheaply enough. It would look cool, mostly. So I'm not about to spend the price of a locomotive on something just to look neat. --Randy
I built a couple Rob Paisley devices using the Harbor Freight meters. They work very well. Cheap enough. The club NCE 5 amp power pro trips at about 4.95 amps. At home, The current is very close to what my NCE Power Cab controller shows.
My Harbor Freight meters show around 14 VAC when connected to the rails. Bad connections with a load show up as a lower voltage on the layout. I am only looking for a "trend".
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.
maxman richhotrain I don't see that meter on the Harbor Freight web site. Here is a typical: http://www.harborfreight.com/7-function-multimeter-98025.html
richhotrain I don't see that meter on the Harbor Freight web site.
That's the one, I have like a half dozen of them. Watch the flyers they send, you can get them for $3, and every once in a while free. Haven't seen them fre for a while now, but I had a flyer the othe week and they were $3. I should have gotten more, but I need to reduce what I have right now so I cna move, not gather more. Also, the backlit one for $1 more might be even better for my DCC panel meter idea.
richhotrain Thanks, maxman. I wonder if that is what Randy was referring to because he mentioned a $3 price. Rich
maxman richhotrain Thanks, maxman. I wonder if that is what Randy was referring to because he mentioned a $3 price. Rich By now you've seen Randy's reply that the meter I linked to was the one he meant. Harbor Freight always has some sort of coupon with their ads. Here is a link to one showing 20% off any item: http://instore.thread.co/retailmenot/harborfreight.com/offer/NMTQJAEZQVCTFD4C3WMB4DVX5M. That will bring the price down to $4.
I had not seen Randy's reply until after I saw yours (I always rush to read your latest replies before doing anything else - - LOL).
Seriously though, I appreciate the follow up.