Where can one find a meter that will show the amount of voltage through a circuit on a constant basis ... like the meters that are on the larger transformers I would like to monitor the voltage across the various sections of my layout.
thanks!
ed
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I am interested as well as I purchased the following but have not been completely happy as I cannot figure out how to get it to match my multimeter readings
Lionel, MTH and K-Line have all designed boxcars with an on-board voltage meter that you might be interested in and you could build your own with an inexpensive digital display meter.
It is difficult to find an AC digital ammeter accurate at our voltages
Finding the AC meters is always the tricky part, most of the digital meters are of the DC variety. A few years ago, I painted an old beat up PW boxcar and installed two AC 0-20V meters, one on each side. Obviously, I also had to install collector trucks to grab the voltage.
The tricky part was the meters required a totally isolated DC supply besides the measured voltage. So I had to cobble together a little supply that fed a 12VDC<->12VDC Isolated switching supply module. This powered the meters and they can then measure the track voltage.
Rich, the digital meter is 0-300 volts, so it's not that useful for track voltage, it has a 1 volt resolution. I can find those all day.
Rich....the analog meter is PERFECT! Thanks for sourcing that out!! I ordered the digital one as well but can’t figure out how to use it!
Ed
"I ordered the digital one as well but can’t figure out how to use it!"
What's the issue? It requires 5 Vdc to power the circuit. Then the meter indicates 0-300 Vac. How many wires coming out? 2? or 4? or does it use internal batteries?
Most need a separate dc power supply to light the meter.
Ah forget that! Over my pay grade!!
thanks!
ed
Note that the separate DC supply to power the meter must be TOTALLY isolated from the voltage being measured. That's a key point!
If you do a search on eBay for the exact title below, the top result that comes up is a suitable meter, and they have it in the proper voltage and current ranges.
Here's the drop-down that shows you all the varieties available. You'll note the 0-10A and 0-20V meters are there, ideal for most layouts.
Are looking for just track voltage in general or voltage in a section as the train rolls down the track. If you want a freight car with a voltage meter in it, Lionel made a Great Northern work car with a meter some years ago .
If just track voltage in general, I use a digital multimeter from Harbor Freight with the probes stuck in to the ends of a spur track of Gargraves or tubular track. I have one attached to my transformer and one on a spur. That way I can see the voltage drop through the tracks.
At times Harbor Freight offers the meters free or for $1.00 with purchase . I bought a bunch of them, they last about 5 years at constant usage.
Thanks for feedback! I am looking to monitor the output from transformers to lighting which have a voltage capacity which is less that the max output of the transformer. I have already melted a few bulbs and so I want a way to ensure it doesn’t happen again.
i have a basic variable out transformer which I intend on putting stops on so I cannot move the lever beyond the max output that I need. Plus it looks way cool with all the meters in the control panel 😎!
Somewhat related, has anyone used the '70s era transformers from Western Electric? They were for those specialty phones and have a 6-8v output. Thought that would work for accessories.
Well, I ordered one of each of the ones I posted, but the results are less than stellar with a chopped waveform transformer. On the bright side, they came quickly. 
I suspect those kind of results aren't going to please many people. There is a 75 ohm resistor across the output for a small load, this prevents the stray AC from giving us false readings.
The meter on the right is a Fluke 8012A True-RMS meter, the meter on the left is the one I described in a post above. I don't expect the ammeter to do any better with a chopped waveform, so these aren't actually ready for any layout using one of the many chopped waveform transformers.
Pictured is a mini AC/DC voltmeter which I have found to be quite accurate. It's quite small (less than 2" long). I have carried it to many club meetings and used it to double check voltage levels before running trains. It was quite reasonable in cost as well.
Bob, I seriously doubt it's any more accurate than the ones I posted on chopped waveforms. Perhaps you could perform a test next to a true-RMS meter and give us the results.
https://ogrforum.com/...2#149239177048400272
gunrunnerjohn mentioned that the DC power supply must be isolated from the tested voltage. so i bought the same meters on ebay (voltage and current) and also AC to DC converter to provide the 5v DC needed to power the meters. hooked the converter to one of my accessory Z1000’s and then tried to display the voltage from another Z1000 providing track power. as soon as i connect everything, the external fuse blows on the track powering Z1000. is this because all the transformers are connected? how do isolate the DC power to the meters? would i have to use a plug similar to those that supply 5v power to lighted menards buildings?
The power to the meters is separate from the measurement interface, but the power MUST be totally isolated. I use a DC-DC isolated power block for mine.
Here's a place with a ton of DC-DC Isolated converters, pick the voltage and current capability you need.
Thanks gunrunnerjohn. I am a novice and don’t really understand what to do with the converters you have suggested. Wondering if this might work to supply the needed isolated 5v power?..
The converters I reference are really simply an isolation layer. If you're doing a fixed location meter, then you can use any cheap 110VAC-5VDC brick to supply the power. The isolation modules were specifically for rolling stock where a power cord would probably be a serious limitation as to range of motion. 
Yes, these meters will be fixed at a location near the control panel of our layout. I am gonna try the brick referenced in previous post. Thanks again John for your help!
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