Question about volt/ammeter range

I doubt if you will see much on the 0-50 scale. There are any number of both analog and digital VAC ammeters in the  0-10 amp range available that will provide a comprehensive reading for a single engine----- in the range of 2-3 amps. 

Dewey,

 

Thanks for the quick reply. I should have said I would be running between 1 to 4 engines tops.

this may be old school thinking, but i'm always a little leery about running large currents though these sort of digital meters.  i'd much rather get a more accurate current reading by passing the load through a beefy (~20 watt), 0.05Ω 1% resister and reading the voltage drop.  even at 10 amps you'll only be dropping 0.5V.

I use mostly 0-15 and 0-20 amp range analog meters, one for each 10 amp capacity power district. Inexpensive meters at 2 to 2-1/2%  + or [-] variation. Analog is easier for me to read at a glance but digital works just as well.

The photo below on a former layout shows 0-20 amp range meters wired to five different 10 amp capacity power districts. I was often running two long lighted passenger trains with dual engines on the same district which accounts for my 0-20 amp range meters. If you are running as many as 4 engines in a single power district an 0-15 amp will still handle it okay. 

Given that the meter in question is obviously at least a 3.1 digit meter, I suspect that expecting measurement down to around 1/10 of an amp is a reasonable assumption.  The kicker is they don't mention the voltage range it measures, very curious.

 

I send a question about ranges to them, I'll post the answer if/when I receive it.

Thanks for all of the replies! I'm trying to learn as much as I can about digital panel meters. I found another dual volt/amp meter that has a green and red lcd display, which I think looks pretty cool. It has a detection rating of 100v ~ 300v. Does this mean it will only detect voltage in this range, and thus be unusable for 20v? I've tried to google this, but haven't seemed to hit the right key words yet.

One more question! Do any of you guys know any companies in America that sell dual panel meters? Seems all I can find are imported from China.

I think you'll be pretty much restricted to China for something like this unless you want to go for big bucks!

 

As far as the other meter's specifications, how about a link to it?  I like the red and green feature, sounds like a good idea.

 

The 100-300 V may be a compressed scale meter that won't work for low voltages, hard to say without more details.

Dual panel meter on eBay.

 

I like the look of this. I'm looking to see if I can find one with a lcd/led screen.

It's pretty clear from their diagram that it is indeed a compressed scale meter, I don't think that one is going to work for you.

 

Another point to consider.  Many of these meters will require a separate ISOLATED DC supply for powering the meter electronics.  This is not mentioned in all the ads.   I got stung by this when building my track voltage monitoring car, I had to include an isolated DC switching supply for powering the meters.

 

Here's a pair that appear to have the ranges desired.  Even though the voltmeter has a maximum range of 500 volts, it appears it would be suitable.

 

Red Ammeter

 

Blue Voltmeter

Thanks John!

If you're doing multiples, I'd get one and see how it works first.

Not sure why you want dual meter,You can get single digital meters for about $8 ea.

They have internal resistors so you can scale them to suit.

 

Al W. 

Well, one is volts and one is amps...

I bought six 0-30V acv volt and six 0-15Amp Acv amp analog panel meters. No shunts required. About $9.00 ea. Chinese close out. All at same time from a reputable supply house online. 4 sets for my ZW-C and 2 sets for two Powermasters. Going under the assumption that analog meters are most accurate in the lower 2/3rds of the scale. Once they were wired, they were all pretty much relatively accurate to the naked eye. Which is all I cared about anyway. Then I noticed that on Channel C that I still had a Tmcc Lockon still inline on a 135 watt brick. I had been using it to protect a 1st generation Powermaster which I realize now may not really have been useful. I was also annoyed that the meter was indicating almost a 3volt drop relative to the other 3 bricks. Swapped the wires and same reading. Next I thought it was a bad controller on the ZW-C. But being thorough, I swapped the channel to a different meter. Sure enough out of the 6, I got one voltmeter that got by QC if such a thing exists in China. Chances of getting a matching replacement is pretty slim so I will just use it for a lighting circuit after I re calibrate it with a fine line marker. Not enough range in the adjustment screw and I would prefer to have true Zero anyway. But they do have that postwar high tech look and I like them for the same reason that I prefer an analog speedo or tach, I seem to react to the movement quicker vs my digital alarm clock that puts me back to sleep in the morning. FMH

Another thing to consider is if the meter reads "true rms" or not. I don't see any mention of this meter in the ebay ad. Mostly, our track ac is not a pure sine wave and the readings will be inaccurate. However, the readings are repeatable. In the case of the track voltage car I built, I was only looking for relative readings, ie, where the voltage might take a dip. So a true rms voltmeter wasn't necessary.

I think it's a lot more important to have repeatable readings that worry about True-RMS, at least IMO.  I doubt many of the cheap digital meters are true-RMS meters.