Does anybody know if an ac combination Volt/Amp digital panel meter exists where the voltage is rated lower than 80 volts? If so can you identify a source for me?I have 4 power districts and want to monitor voltage and amp draw on each section.Trying to save some room on the pannel.Thanks in advance.Nick
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Nick, I bought this meter at the York show in the Orange Hall a few years ago. I believe they still attend the shows. I cannot remember what I paid for it, but is does work great. The indicator lights on top will tell you what type of voltage is going through the meter. RR amp meter, DCC,AC,DC. American Hobby Distributors 1-800-671-0641.
Took me awhile to find it with the lame search engine they use...
Here's a place that actually sells them 
Thanks Cjack for contributing. I believe I bought mine, about 5 years ago. I did not pay near that much at the show back then. The price has sure increased. I think I purchased it from the stand that sells the BCR's in the orange hall.
Ouch! At $95, we need Stan to work on this one.
Search eBay for something like "ac meter digital panel 20v".
Contact Art's (Chugman's) son, Jim Williams ibew.701@att.net
He makes panels that include meters; I dont think his are $100 meters.
Here's one that looks suitable, ebay: 140970861562
Not a lot of choices...
The one GRJ points to is the only thing I have seen for quite a while. Good find!
I have been looking for a digital combo meter for our train voltages for quite a while with no luck. Even the single digital meters in lower voltage and amperage have become quite scarce the last couple of years or so.
What will happen when more then 19.99 volts are applied? Several of my MTH bricks put out 21 volts.
Don't know, you'll have to buy one to see. My guess is it just indicates over-range, that's what some of the ones that I bought previously do.
Note the eBay 20V AC voltmeter requires a source of DC to power the meter. The 80V AC meters are self-powered (from the AC voltage itself). There have been several earlier OGR threads about how to provide this DC power when multiple meters are involved; there are isolation/grounding issues that must be considered.
I have not seen/used it but what's nice about the RR Amp meter is it apparently measures TRUE RMS voltage and current. Very few digital (or analog needle type) panel meters measure True RMS. "True RMS" is one of those beating-a-dead-horse topics.
In practice, here's what happens on OGR.
Step 1. Someone reports some problem and provides some voltage and/or current measurements that seem screwy or not right.
Step 2. He's asked to describe the measurement apparatus (true-RMS or not) and exactly what is being measured (pure-sine vs. chopped-sine transformer).
Step 3. Compensations/adjustments are made to the numbers for diagnostic purposes. Life goes on.
Call me cynical but that's the way I see it...and it does seem to work. Lather, rinse, repeat.
Thanks for your help in this.I will look into all of these options.I guess if I have to I can eliminate the volt meters.I am using fixed voltage power bricks.The Amp draw is most important to me in most cases.Nick
Got one of these coming from china..should be interesting..was about 8.00 shipped.
I think you'll find that it only measures down to about 80 volts or so.
gunrunnerjohn posted:I think you'll find that it only measures down to about 80 volts or so.
I think your right..i am interested in running a TIU out track lead through the inductor ring to see what amps i read.
Here's an option that's outside the envelope. You can monitor your different districts by using 1 amp meter, 1 volt meter and a rotary wafer gang switch. This is old school stuff but it's a way. Back in the 60's when I was a HAM radio operator we built our own transmiters, receivers and test equipment and the rotary gang switch was a common component.
Here's a typical schematic of a 4 pole rotary switch. Each district would have it's own pole. Of course you can only monitor 1 district at a time so you just turn the switch to the next pole/district.
BTW, wiring a rotary switch will surely test your soldering skills.
Running track power for the ammeter through that would be a crapshoot, I doubt you'll find many rotary switches like that with 10A contacts. Besides, having meters for every power district is much nicer as you can spot issues by a simple scan of the panel.
gunrunnerjohn posted:Running track power for the ammeter through that would be a crapshoot, I doubt you'll find many rotary switches like that with 10A contacts. Besides, having meters for every power district is much nicer as you can spot issues by a simple scan of the panel.
Exactly...this is my goal
gunrunnerjohn posted:Running track power for the ammeter through that would be a crapshoot, I doubt you'll find many rotary switches like that with 10A contacts. Besides, having meters for every power district is much nicer as you can spot issues by a simple scan of the panel.
The heavy current (and incidentally High Voltage) ones cost hundreds of dollars if you can find them...
https://www.surplussales.com/RF/rfcerrot_1.html
...which makes the $95 volt/amp meters a bargain .
Not to mention you have all that current and power running through one little spot on the panel. If I were using a rotary switch, I'd be pairing it with a bunch of relays, dirt cheap to get them in 10A capacity. 
I was looking for a digital ammeter that would work on AC current and the only thing I found were these $100. meters. I would have liked to have 3 panel mounts to monitor current draw on the track sections of my layout. At present I now do have 10 amp analogue meters on each of these but the low end readings on these are almost useless. Running trains that operate with can motors the needle barely will move, if I run a double motored engine with the older open frame motors that will register but again not very precise. I ended up purchasing a digital clamp meter that has a low range of 0-40 amps and with a scale to .00 per amp. This was not the ideal choice for me but it does give me the opportunity to check amp draw on each of the sections of my layout. With this meter the readings for single can motored engines show 1/2 to 3/4 amp depending on speed and load, the dual open framed engines show 2 1/4 to 3 1/2 amps. This meter was priced under $40.00 and will suffice my needs and wants at the present time. The paperwork claims accuracy of + or - 2.5% of the reading in the 40 amp range.
Ray
willygee posted:Got one of these coming from china..should be interesting..was about 8.00 shipped.
Please let us know what it reads when it arrives. I am thinking like GRJ on the voltage, but would be interested in seeing what actually happens when you hook it up.
To all: I asked one of the ebay sellers about a volt/amp/watt (or anything else digital they might have) meter that was in the AC - 0-30 volt and 0-20 amp or so ranges. I'll report back when they reply.
Some of the labeling on these seems to indicate they have multiple ranges. That is what got me wondering? I wonder if there is just something in the meters that they change to get a different range. A jumper would surely be TOO easy?
gunrunnerjohn posted:I think you'll find that it only measures down to about 80 volts or so.
I think it will actually measure below 80V and perhaps down to 0V AC. I believe the issue is the module requires at least 80V AC to provide power to the electronics. Your photo suggests there's only 2 wires (ignoring the current loop) going into the module suggesting the meter is self-powered...in other words receiving its power from the incoming >80V AC voltage itself.
For about $1 on eBay you can get miniature AC-to-DC isolated power supplies that operate over the universal "wall-outlet" voltage range providing low-voltage DC output. And that's the quantity 1 price.
If you inspect the meter itself, perhaps there's a simple way to bypass the AC-to-DC power supply on the module and directly supply 5V DC (or whatever it takes). If the voltmeter is 200V range, I think you'll get 0.1V AC resolution which ought to be good enough for train stuff.
I wonder if there are any other applications for a low-voltage (O gauge train) AC digital panel voltmeter/ammeter. That's my interpretation of why they aren't manufactured. And while it's easy to imagine someone else doing the job, I think you could sell a bucket of these as this issue comes up over and over with the same cupboard-is-bare results.
Stan,
There were several of the low voltage AC digital meters (I believe both volt and amp, IIRC) available a few years ago when I copied GRJ's voltage car (with his help, of course). Then I looked again a year or two later and they had just vanished, gone extinct? I agree that where would be a demand for these, but no idea what happened to the ones that used to be available? I don't remember ever seeing one of the combo meters in our ranges though?
I was thinking about contacting the seller I got them from, but the ebay listing is too old and has dropped of my 'purchase history' list. And the old memory is also too far gone to remember who it was?
I'll venture to say that it won't be doing all that well at low voltages, but I'd love to be proven wrong.
I also see that they don't have any decimals in the voltage, so the resolution will be pretty poor.
I searched in vain and simply decided to go this way.............. 2 for $9....E Bay
It seems many of those digital panel meters from a few years back required an isolated DC power source to power the digital electronics. I'll bet a lot of customers complained and said their application was to monitor wall-outlet line voltage and/or current and what a nuisance to supply an isolated 5V (or whatever) DC. So manufacturers responded by integrating 50 cents of electronics (e.g., something like the AC-to-DC module above) to stepdown 80V AC to isolated 5V DC and, voila, a self-powered combo panel meter. The combo meter uses a current-transformer "doughnut" sensor so that provides the isolation for the ammeter side.
I think the check-mark boxes you refer to are 20V, 50V, 100V, 200V, etc. to define the full-scale voltage. That is, you won't find a checkbox for the minimum voltage. My point is the meters should adequately measure down to 0V...hence my earlier comment that a 200V range AC meter should adequately measure O-gauge AC track voltages. It's getting the DC power for the digital electronics that is the issue. And it's that integrated AC-to-DC power supply (not the meter itself) that limits the ability to measure below 80V AC. In other words, I believe this latest crop of 80V AC meters have at their core a perfectly functional 0-200V AC meter (i.e., all the way down to zero, with 0.1V resolution) with an AC-to-DC power supply tacked on. Of course, talk is cheap and I too would love to be proven wrong.
Again, it would be a worthy project for someone to look at that AC-to-DC power supply on a combo meter. In principle, power converters are about Watts per cubic inch. So it's not a "technical" limitation but I'm doubtful any panel meter manufacturer has O-gauge "low-voltage" AC on their radar.
willygee posted:Got one of these coming from china..should be interesting..was about 8.00 shipped.
This is the one that I did't want to buy.I know you can't believe everything you see and hear on the internet but a guy on you tube demonstrated that these peter out below 80 volts.Please let me know if you have any luck with it.Nick
rockstars1989 posted:willygee posted:Got one of these coming from china..should be interesting..was about 8.00 shipped.
This is the one that I did't want to buy.I know you can't believe everything you see and hear on the internet but a guy on you tube demonstrated that these peter out below 80 volts.Please let me know if you have any luck with it.Nick
Will do..when it arrives i will pop the cover and post..Stans iso ac/dc board is interesting.
willygee posted:rockstars1989 posted:willygee posted:Got one of these coming from china..should be interesting..was about 8.00 shipped.
This is the one that I did't want to buy.I know you can't believe everything you see and hear on the internet but a guy on you tube demonstrated that these peter out below 80 volts.Please let me know if you have any luck with it.Nick
Will do..when it arrives i will pop the cover and post..Stans iso ac/dc board is interesting.
Meter finally arrived....reads Z1000 voltage and works up to 4.5 amps and then starts to flicker. Total load: 5 engines idling and 5 engine mu in video pulling mostly intermodal(30 cars)
I'll bet Stan will want me to crack it open and photograph
Edit: board image
Thanks for posting the guts. In looking up the "YB4835VA" it appears the voltage resolution for all versions is 1V at best.
So while I still believe the meter can "measure" 19V AC (or lower) for typical O-gauge command voltage, I'm speculating it needs more than a 19V AC power supply to function. That's my guess as to why it's flaking out on the current reading when it goes near 5 Amps (I notice the voltage reading also goes to 0).
So while I believe the components can be modified to function properly at 19V AC, I don't think there's a practical way to change the scale to get 0.1V voltage resolution. The frustrating thing is it probably just a few lines of software but again no practical way to hack into the code.
Just my opinion but I'm holding out for 0.1V resolution.
Thanks stan..if you want me to tamper with this just say the word
..after all If it ain't broke,break it and make it better
So while I believe the components can be modified to function properly at 19V AC, I don't think there's a practical way to change the scale to get 0.1V voltage resolution. The frustrating thing is it probably just a few lines of software but again no practical way to hack into the code.
Just my opinion but I'm holding out for 0.1V resolution.
Actually, there is almost certainly a resistive or capacitive voltage divider on the board, doubtful that they are running line voltage directly to an ADC. But again, without having a unit in your hand, the components would be difficult to identify.
I'd suspect software or a jumper to move the decimal point, and a value change on the board for the scaling. You could get a lot of ranges out of one IC that way.
Many of these meters are offered with different range options, so there may be a simple resistor change or jumper.
I don't view 1 volt resolution as all that useful for our purposes, so I'd have to pass on something like this.
gunrunnerjohn posted:Many of these meters are offered with different range options, so there may be a simple resistor change or jumper.
I don't view 1 volt resolution as all that useful for our purposes, so I'd have to pass on something like this.
True, but if the input signal goes through a 20X attenuator to get 1 V resolution, changing the attenuator to 2X gives you .1 V resolution. Doesn't help with the decimal point, though.
Just glue an LED in the decimal position. 
What would it take to bring a meter that fits the train community's needs to market? Is it outside the expertise available on the forum to do this? Maybe we all should shark tank this development so we all could benefit. I don't bring any expertise to the table but I can afford to donate to the kitty to get it started. TW
TedD, all we need is for the price to be more admirable for purchasing the RRampMeter meter. This meter is a great and accurate meter, just very expensive.
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